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222 Cards in this Set
- Front
- Back
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charge of electron and proton
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(-/+) 1.602 x 10^-19 Coulombs
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Element shorthand
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Thomson Experiment
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Determined the opposite charges in an atom and that the charge was a fixed quantity. He manipulated a beam of electrons using an electric field. The beam bent in a uniform matter towards the positive charged plate. Because the arch of deflection was constant, Thomson concluded that electrons have a fixed charge to mass ratio
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positron
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an anti-electron. It is the same mass as an electron, but positively charged
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neutrino
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It is nearly massless and does not have a charge. Difficult to detect.
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gamma ray
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a photon, photons do not bend in an electric field
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what is a photon
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A photon is the fundamental unit of light. It acts both as a particle and a wave. Photons have no mass and differ from other elementary particles. They do not carry charge.
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Is everything made of atoms?
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No. Everything which has mass is made out of atoms. The universe is only made up of 5% mass. Also, Sound, light, and heat only exist as energy and not as atoms. They do not have a mass associated with it.
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muon
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same charge as an electron by 200 times more massive
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Mass spectrometer radius of curvature (equation)
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(mass*initial velocity)/(magnitude of charge)(strength of magnetic field)
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Millikan Oil Drop Experiment
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Charge oil drops with electron by shooting a beam of electrons through it. this is inside a glass cylinder where a uniform electric field exists. the oil droplets are falling due to gravity, but if we suspend the oil drop by exerting a counteracting force, we know that the force equals the force of gravity and solve for the charge. q=(-mg)/E
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Rutherford Experiment
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Determined that atoms have dense nucleii but are mostly empty space. Basically he shot alpha (can also do this with electrons and x-rays) particles (helium) through gold foil and saw if they went through it or deflected. Based on the fact they only deflected some of the time, he concluded that the atom is mostly empty space with one dense nucleus that is not spread uniformly throughout the atom. He also the plum-pudding model when he shot xrays at the gold foil and not all of the xrays went through. The "gaps" of where the xray didn't go through showed that the gold nucleus was actually tightly packed in the center of atom the spots were uniformly spaced).
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Heisenberg's Uncertainty Principle
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states that you cannot quantify a particles position and velocity at the same time
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Equation used to determine energy of an electron in its principle energy level
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E= (Z^2/n^2)
Z=nuclear charge (# of protons) n=electronic energy level |
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equation: Transition energy between different energy levels of an atom. In this case, for hydrogen. As it is most often used for hydrogen.
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Rydberg's constant*h (planks constant)*c (speed of light) = -2.178*10^-18
E=-2.178*10^-18 (Z^2/n^2) Z=nuclear charge (# of protons) n=electronic energy level |
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Energy of photon equation
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h*v (frequency)=h*c/wavelength
h=6.626×10^−34 J*s c=3*10^8 m/s |
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Number of electrons in subshell
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2(n)^2
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what is Effective Nuclear Charge (Z eff)?
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Effective nuclear charge is the overall effect the nucleus has on its valence electrons. The net charge exerted upon the valence electrons You basically add the number of protons and subtract the number of shielding electrons (all non-valence electrons).
ex. Zeff of Li=3-2=+1 F=9-2=+7 It makes sense why Fluorine is so electronegative now, doesn't it? It has a huge pull on its valence e-. Effective nuclear charge increases left to right |
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Define paramagnetic
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An atom or molecule that has at least one unpaired electron. When a magnetic field is applied, the electron spins align itself with the field
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Diamagnetic
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An atom or molecule with no unpaired electrons, thus not susceptible to a magnetic field.
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Pauli's exclusion principle
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no 2 electrons can have the same set of quantum numbers (n,l,ml,ms)
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Hund's rule
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Electrons completely fill lower energy levels before starting to fill higher energy levels
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Aufbau principle
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electrons are added one by one to the shells
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What are quantum numbers
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A set of four numbers that uniquely describe an electron within an atom. They are used to describe the motion and location of each electron in an element.
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what is n, the principle quantum number
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n describes the shell where the electron resides. The shell is basically the radius of the electron's orbit, between the nucleus and its energy level. Any positive integer above 0
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l, angular momentum, azimuthal number
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Describes the orbital shape in which the electron resides. An orbital is the electron cloud formed by the orbiting electron. It can be a positive value or zero
0=s, 1=p, 2=d, 3=f, 4=g, 5=h, 6=i |
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magnetic (m sub l) quantum number
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describes the orientation of the orbital about the axis or plane (ex, is it px, py, or pz?). It can be anywhere in the range of -l to +l (l=angular momentum number),
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spin (m sub s) quantum number
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describes the rotation of the electron on its axis (clockwise or counterclockwise). Electrons are like the earth, they spin around its own axis while orbiting the nucleus. It's either positive or negative 1/2 (spin up or spin down)
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What do s, p, d blocks comprise of?
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s-block: metals
d-block: transition metals where trends aren't obvious p-block: metals, metalloids, AND nonmetals. |
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Name Trends:
nuclear effective charge, valence shell, electronegativity, ionization energy, electron affinity |
The all increase in the direction of the huge arrow
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Ionic radius
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cations are smaller than neutral atoms (which makes sense because with the loss of an electron, the nucleus can have a greater pull on its electrons and the atom becomes more compact...less repulsion between electrons)
anions are larger than neutral atoms because they have an extra electron and there are more repulsive forces at work and the atom expands valence electrons account for the size of cations, neutral atoms, and anions |
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Angstrom
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1*10^-10
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picometer
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1*10^-12
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atomic radius definition
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the distance from the center of the nucleus to the edge of valence cloud of electrons.
Note He actually has a larger radius than H, thought because electrons in first shell repel one another the most due to their nearness to the nucleus (they are very close together) |
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Ionization energy
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the energy required to remove the outermost electron from the valence shell (to make an element into a cation)
-the easier to ionize an atom, the easier to oxidize it -higher ionization energy=harder to rip off electron opposite of electron affinity |
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Electron Affinity
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it is the measurement of the energy absorbed or released when an electron is added into the valence shell. It can be endo or exothermic. It is opposite of ionization energy.
the higher the electron affinity (kj/mol) the less the element wants an electron. it's almost not who wants the electron more...but who can stand to have it best. That's because that is the energy released when an electron is added an element with a high reduction potential has a high electron affinity |
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Electronegativity
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A measure of an atom's tendency to gain and retain an electron from a neighboring atom within a bond. Formally defined as the ability of an atom to attract towards itself the electrons in a chemical bond.
It's related to both the atom's ionization energy and electron affinity Pauling scale used to measure electronegativity when electronegativity difference exceeds 2, the bond is ionic. Less than 2, and the bond is covalent |
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Great question regarding electronegativity
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D
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Alkali Metals (group 1)
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Some of the strongest reducing agents (get oxidized to a 1+ cation)
They react with any compound or element that has a high electron affinity reactivity increases as you go down the column do to increasing atomic radius Cation is very soluble in water with almost any anion |
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Alkaline Earth Metals (Group II)
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Strong reducing agents, but not as reactive as alkali metals. Mostly because they readily lose 2 electrons to form 2+ cations (they need to lose more than one electron). They are also not as soluble in water.
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Chalcogens (group VI)
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Oxygen and below. Oxidizing agents (get reduced, need 2 electrons to be stable). Their reactivity goes gets smaller going down the column because of a diminishing electron affinity. They are often insoluble, although depends on counterion, cation.
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Halogens (group VII)
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Strong oxidizing agents, most are soluble in water (although depends on their counterion (cation), reactivity also decreases going down the column due to decreasing electron affinity
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Inert gases, the noble gases (group VIII)
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Most exist as monatomic and form no bonds. Some, however, krypton and xenon are known to form bonds with halogens. The halogens are more electronegative in this case.
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Absorption (Excitation of an electron)
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The gain of energy by an element or molecule resulting in the excitation of an electron from a lower energy state (often ground state) to a higher energy state (an excited state). The form of energy absorbed can be light, thermal, mechanical, and electrical.
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Emission (relaxation of an electron)
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Loss of energy in the form of a photon by an element or molecule resulting in the relaxation of an electron from higher energy state to a lower state.
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Absorption Spectra
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Shows all light except what was absorbed, which appears as a black line due to absence of light. They are black lines in a rainbow
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Emission spectra
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Emission spectra show only the emitted light. They are colored lines against a dark background (due to only selected frequencies being emitted). They are stripes of color.
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Lyman Series
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Hydrogen electrons emit photons in the ultraviolet region of the EM spectrum once they come back to n=1 energy level. All transitions are less than 400 nm
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Balmer series
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Hydrogen electrons emit photons in the visible range once coming to n=2 energy level. All transition are between 400- 800 nm.
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Paschen Series
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Hydrogen electrons emit photons in the infrared region once coming to n=3 energy level. All transition are over 800 nm.
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Brackett Series
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Hydrogen electrons emit photons in the low infrared and microwave region once coming to n=4 energy level.
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Electromagnetic Spectrum (EM spectrum)
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uses of radio waves and low energy microwave waves
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Used in communications. AM (cheap) and FM (expensive) radio communication. Low energy microwave waves used for cellular phone networks, cable television, satellite, and airport landing systems.
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microwaves higher energy
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used for cooking by rotating water molecules within food,
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infrared
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remote controls and other line-of-sight communication methods
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Visible spectrum
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700-400 nm
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Red
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700-627nm
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Orange
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627-594 nm
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Yellow
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594-561nm
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Green
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561-477nm
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Blue
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477-438 nm
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Violet
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438-400
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ultraviolet
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20-400nm
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Rods
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More numerous (120 million) and more sensitive than cones...but not sensitive to color.
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Cones
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Only 6-7 million in comparison tot he 120 million rods, are sensitive to color, and are concentrated in a central yellow spot known as the macula. the center of the macula is called the fovea centralis and is rod-free, but jam packed with cones.
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How one sees Emitted color
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Can be seen at night because their source is emitting light. Literally electrons are giving off energy in the form of a photon of a certain wavelength of light. What you see is what you get. A great way tot es if something is emitting color is to ask yourself whether you can see it in the dark.
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Difference of primary color in pigment and light
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Primary colors in pigment (magenta, yellow, and cyan) are the secondary colors of light. The primary colors of light (red, green, and violet) are the secondary colors of pigment.
Coooooooooooool. |
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How one sees reflected color
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White light hits an object. Some colors are absorbed and some are reflected. The reflected radiation appears as a color that is a combination of the reflected photons. We see the complimentary color of the frequency that had the highest intensity of absorption. Basically, red wine absorbs green color, and we see the complimentary form of it. Reflected colors can only be seen in the presence of an external light source.
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What color light does chlorophyll absorb?
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red. That is why we see plants as green.
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What is Fluorescence?
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The conversion of ultraviolet light into visible light. This is done by a material with a semi-stable state absorbing an ultraviolet photon, relaxing slightly giving off an infrared photon, and then relaxing all the way to ground state giving off a visible photon close to UV range.
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What is photoelectric effect
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An incident photon causes the release of an electron. Basically says that a compound can be ionized with a photon as long as the photon has energy greater than the ionization limit of the material. The energy holding the electron to the surface of the solid material is referred to as the binding energy. Once electron is ejected it can be harnessed as mechanical energy or stored as potential energy via electrochemical cell). The higher frequency of the photon that ionizes the material, the more KE +e-.
Ionization energy is important as it is the threshold for the photoelectric effect to occur. |
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Nuclear Decay
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particle loss from the nucleus. Also known as FISSION. Particles with more than 56 amus tend to undergo fission.
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Nuclear Capture
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The process of particle gain by the nucleus. Also known as FUSION. Particles with less than 56 amu tend to undergo fusion.
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What is an alpha particle?
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a helium nucleus, 2 protons and 2 neutrons
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What is a beta decay?
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neutron---> proton + electron (and actually an anti electron neutrino....)
The electron is a super fast moving electron that moves out of the atom |
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What is a positron?
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a positively charged particle the same size as an electron
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What is a neutrino?
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An uncharged particle with the mass of an electron
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What kind of photons does a nucleus absorb to get to an excited state?
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a gamma ray
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What is a positron decay?
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When a proton turns into a neutron by emitting a positron.
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1/2 life
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The amount of time it takes half the substance to decay to another form. First order decay is exponential while 0-order decay is linear. First order decay, half life is constant with changing concentration. In 0 order decay, half life decreases with concentration.
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What does it mean when a pore distinguishes by charge?
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The greater the charge of the cation, the slower the migration through the pore
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When asked about whether a compound is polar or nonpolar
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Cis compounds are ALWAYS polar
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What is the formal charge of an amino ligand (NH3).
For example, Cr(NH3)6^+3 |
neutral. Cr has a +3 charge
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what is the formal charge of a water ligand. For example, Co(H2O)6^3+
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H20 ligand is neutral, Co carries a +3 charge
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What is the ionization energy for hydrogen?
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The most important thing to note is n initial= 1, n final=infinity, and having infinity in the denominator makes the number zero (who knew?).
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What does the atomic number represent (Z)?
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NUMBER OF PROTONS
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What does the atomic mass number represent (A)?
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The number of PROTONS + NEUTRONS!
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Equilibrium question
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What is an equilibrium in a reaction?
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kf [reactants] = kr [products]
kf= rate of the forward reaction kr= rate of the reverse reaction |
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What is the equilibrium constant (Keq)?
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Keq = [Products] / [Reactants] (in Molarity)
*Keq only changes with temperature ---NOT WITH CATALYSTS, PRESSURE, VOLUME, OR MOLES *stoich values become exponents *solids and pure liquids are not included in the equation, only solutes and gases are |
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Kinetics
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The study of rates of reactions, how they combine, how stuff reacts
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What does the Keq equation mean?
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It is literally taking into account the probability that X moles of a certain concentration will be available to be part of the reaction. Ex. If we want 2 of A and 3 of B to yield 5 of C; we're looking at the probability that there will be 1 of A, and 1 of A again, therefore A raised to the 2. Like finding the probability of getting heads 3 times in a row First you find the probability of getting heads once, (.5) and then take that to the ^3 to get the probability of getting heads 3 times!
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Reaction Quotient (Qrx)
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The reaction quotient in an expression of products over reactants when the reaction is not at equilibrium. The relationship between Keq and Qrx dictates the direction in which a reaction proceeds to reach equilibrium.
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Different reactions have special K-values
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How to calculate Keq when you only have moles, not molarity
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This is ok if you have the same number of reactants and products because volume cancels out in both the numerator and denominator
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Standard Temperature and Pressure
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1 atm = 760 Torr = 101.325 kPa, 273 K (0 C) for ideal gas problems, 298 (25 C) for thermodynamics probs, 1 mole of gas occupies 22.4 L
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ICE table for calculating equilibrium
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WHEN TO IGNORE X IN EQUILIBRIUM RXNS?
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The x-value is ignored when the initial conditions are like the equilibrium conditions because the shift is minimal and the value of x is trivial.
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Equilibrium question that took me forever to do.
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Another equilibrium problem
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Another solution. Remember, think about the problem. Conceptualize it so you don't have to do math...
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what does isochoric mean?
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constant volume
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dynamic equilibrium
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a state where the system is continually reacting in both the forward and reverse directions. If it was a static equilibrium, the system would not react once equilibrium is reached.
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complex equlibrium
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a balance between 2 separate reactions.
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Le Chatelier's Principle
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If an external stress is applied to a system at equilibrium, the system will shift itself in such a way that the stress is partially relieved and equilibrium is reestablished. An external stress can be changing moles (concentration), pressure, volume, and temperature (although changing T can change K)
When a reaction system is not in equilibrium, the same calculation yields the reaction quotient. If K is not equal to Q, then the system is not in equilibrium, Adding a pure solid or pure liquid does not disrupt the equilibrium constant ***Le chatelier's principle deals with changes to a system that starts in equilibrium |
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What does isothermal mean?
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No change in temperature
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Another equilibrium example that raped me
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Take note that it wasn't obvious to me here that in D the number of gas molecules were equal on each side of the equation for D.
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what are the types of containers used in equilibrium reactions and what are their differences
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Flask, made of rigid material with fixed volume.
Pistons, P initial=P final, one wall if flexible to move and thus volume varies and is susceptible to outside environment |
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Name shifts a reaction undergoes to alleviate applied stress such as pressure, volume, heat
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define adiabatic
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It means that there was no change in heat during the reacton
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What is solubility?
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It is the the breaking apart of a lattice to allow particles to move freely in solvent
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What are the 3 main forces at play that determines whether or not a salt will dissolve in water
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1) lattice energy (the interionic forces in the crystal form)
2) solvation energy (the strength of the attraction between solvent and dissociated form) 3)entropy (the solute form is more disordered than the crystalline form |
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what measures solubility equilibrium?
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Ksp, the solubility product. A low solubility leads to a low Ksp (does not dissolve readily in solvent).
*The relative Ksp values of a group of salts is not always a good indicator of their relative solubility. This is because the units of solubility product (Ksp) vary with the number of ions. Also Ksps have been measured for most salts to see the max amount that dissolves into a given volume at 25 C |
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Define dissolving
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the breakdown of intermolecular forces between molecules as a solid becomes a solute within a solvent. The molecule itself remains intact. Ex, sucrose dissolving in water.
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Define dissociation
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the breakdown of ionic bonds between atoms within a lattice structure as a salt turns into a solute within the solvent. Ex, NaCl dissociating in water, ionic bonds between Na and Cl break and ions are stabilized by the partial charges of water
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Solute
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The species not in highest concentration that dissolves into the solvent, or in the case of a salt, dissociates
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Solubility
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A measurement of the degree of dissolving that a solute undergoes within a particular solvent.
The driving force for solubility is a preference for solvation of molecules (or ions) over the lattice strength of the solid. Also, entropy favors the dissolving process. As the solubility of a compound increases, it is deduced that either the lattice energy of the solid is decreasing, the solvation energy of the solute is increasing, or both effects are taking place. |
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Saturated
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Describes the state of a solution at the point where no more solid (solute) can dissolve into solution. When an aqueous salt solution is saturated, the rate of dissociation of the salt equals the rate or precipitation
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Define supersaturated
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describes the state of a solution where the amount of solid (solute) that is dissovled into solution is beyod the maximum amount at a given temperature. The solution is actually a suspension that when disturbed can form a precipate rapidly. The state can be achieved by first heating the solvent, then adding solute to the solution until the solution is saturated at that temperature. Slowly cooling this solution causes the amount of solute in it to exceed what should dissolve at the reduced temperature.
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Define Molar solubility
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the quantitative measurement of the maximum number of moles of solid (solute) that can dissolve into enough solvent to take one liter of solution under standard conditions. Solvent is nearly always water. Molar solubility can be though of as the x-value in the calculation of the solubility product (Ksp).
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Define Gram solubility
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The quantitative measurement of the max number of grams of solid that can dissolve in enough solvent to make one hundred milliliters of solution under STP.
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Common ion effect
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This results in a reduction in the amount of solid (solute) that can dissolve into solution due tot he presence in the solution of an ion that is also present in the solid. This concept is similar to Le Chatelier's principle, except that with le chatelier's principle, the addition of one of the products (ions) causes precipitation (reduced solubility). With the common ion effect, the ion causing the reduced solubility is present in solution at the beginning of the reaction, rather than being added once the solution has reached a solubility equilibrium.
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Are most salts composted of +1 cation and -1 anion soluble in water at room temp?
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yes
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Are most nitrate salts (NO3-) soluble?
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yes. NO3- is a large anion that forms weak lattice interactions and forms strong hydrogen bonds with water
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Are most salts containing sulfate anions (SO4 2-) with +1 cations water soluble?
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Yes
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Are most salts with -2 or -3 anions soluble?
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no
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Are most oxides (O2-) and hydroxide anion (OH-) salts soluble?
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They are slightly water soluble. KOH and NaOH are notable exceptions.
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Naming salts
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1) Name cation before anion
2) cation often ends in "-ium" 3) anion often ends in "-ide" |
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acetate
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C2H3O2- (CH3CO2-)
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Bicarbonate
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HCO3-
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Carbonate
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CO3 2-
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Bisulfite (hydrogen sulfite)
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HSO3-
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Bisulfate (hydrogen sulfate)
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HSO4-
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Dichromate
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Cr2O7 -2
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chromate
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CrO4 -2
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Dihydrogen phosphate
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H2PO4-
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Hydrogen phosphate
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HPO4 -2
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Hypochlorite
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ClO-
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Oxide
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O -2
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Chlorite
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ClO2-
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Peroxide
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O2 -2
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Chlorate
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ClO3-
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Sulfite
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SO3 -2
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Perchlorate
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ClO4-
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Sulfate
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SO4 2-
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Cyanide
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CN-
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Superoxide
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O2 -
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Nitrite
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NO2-
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Nitrate
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NO3-
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Permanganate
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MnO4-. has 3 double bonds. note, d-block elements can bond to fill up to 18 electrons since the s and p block also play a role. So for Manganese, the 4s, 4p and 3d all are involved with bonding...although 4s and 3d account for the valence.
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Phosphate
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PO4 -3
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Ammonium
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NH4+
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What does the x stand for in Ksp equations?
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the molar solubility
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Highest solubility has to do with the highest molar solubility or highest solubility product?
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MOLAR SOLUBILITY
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What are the 3 methods to determine ion concentration in solution?
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1)spectroscopy, absorbed light at certain wavelength depends on concentration (but must absorb light)
2) measuring amount of salt added and then collecting, drying, weighing, and subtracting mass of precipitate from this value (salt must be very soluble) 3) use ion exchange column to exchange cation in solution for hydronium (salt cannot have acid-base properties and has cation concentration of at least 10 -5) |
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What is the molar solubility of calcium carbonate in water given that the addition of 4.00 mg of CaCO3 to enough water to form exactly 500mL of an aqueous CaCO3 solution yields .55mg of anhydrous precipitate?
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The molar solubility of calcium carbonate: You just subtract the precipitate, the amount that did not dissolve. Then you find the concentration that has dissolved. So...
4-,55= 3.45 *10 -3 grams/100g/mol= 3.45*10^-5mol divide that by .5 L and you get that the molar solubility is 6.9*10^-5 M. That is all. Because that after all is the definition of molar solubility. |
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When do you add the common ion into the Ksp equations?
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In with the initial concentration.
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When comparing values to gauge which compound will precipitate first, what do you look at?
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Molar solubility! The compound with the lowest x, molar solubility, will precipitate out first.
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Fun precipitation chart
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What is an ion exchange column?
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What is chelation?
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The process of making a complex ion via acid base chemistry. A ligand donates a pair of electrons to a central atom, which is typically a metal, to form a coordinate covalent bond. Ca(NH3)3 +2 is an example. The lewis base (ammonia) is the chelating agent.
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When do you use ICE?
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when you are not in equilibrium.
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It is A. The most accurate value for Ksp is found when the molar solubility is the HIGHEST. The general rule is the larger the value, the less significant the error in its measurement. Therefore, find the salt with the highest molar solubility.
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when adding NaCl to water, a precipitate forms
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Ag+ must be in solution because it is the only chloride salt that is highly insoluble. No precipitate is expected between chloride and either zinc or strontium
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The highest boiling point goes tot he solution with the highest molality. Molality is moles per kg of solvent. MX will have more moles per gram than MY because it has a smaller mole mass. Finally, choose C because density of solvent decreases with increasing temperature, We are given a constant volume, therefore mass must is actually less at a higher temp (of water) than it is at lower temps. Think of it this way, as temp increases, you have more and more molecules escaping as gas molecules into the environment. The temp is not high enough to vaporize all the water, but nonethesame, mass get slightly smaller (if volume kept constant). So, moles of solute is now over a smaller mass of solvent. So molality increases with temperature.
Sidenote: density will not decrease if water is in a sealed container. |
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If you divide everything in a reaction by 2, what would the Keq be?
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Take the square root of the Ksp
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What is the inverse of 2*10^4
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5*10^-5 .....or
.5*10^-4 |
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When comparing Q and K in molar solubilities, what do they mean in relation to one another
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Q=K, the salt is saturated in solution
Q<K More reactant in Q, more salt can dissolve in solution Q>K, more product in K, too much salt in solution, very little will dissolve |
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What is the pH scale?
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It has no range, it is limitless in theory. it has limits in practice
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Does a weak acid always have a strong conjugate base?
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No. A weak acid can have a weak conjugate base and vise versa. A strong acid always has a weak conjugate base and a strong base always has a weak conjugate acid.
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what is the relationship between Ka and pKa
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As the relative strength of an acid increases, its Ka increases and its pKa decreases. This means that t stronger acids have higher Ka values and lower pKa values. The Ka and pKa of an acid depend on its strength and not concetration
pKa=-logKa Ka=10^-pKa |
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relationship between pKa, Ka, acid strength, base trength, pKb, Kb
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as acid strength goes up, Ka goes up, pKa goes down, conjugate base strength goes down, Kb goes down, pKb goes up
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strong acids and pka's
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what is the relative pH of weak acid
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pH of 0-14
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what is the pH of a very weak acid?
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pH above of 14
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weak acids
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ammonia based compounds
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are typically weak bases
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What is an alkoxide?
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conjugate base of an alcohol
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some strong bases
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Examples of weak bases
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carboxylates (CO3 -2), alkyl amines (RNH2) bicarbonates (HCO3-), carbonate (CO3 2-), phosphate (PO4 3-) and phenoxides (C6H5O-)
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what does a titration consist of
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If one reagent is a weak acid or base and the other is a strong acid or base
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what are the biggest determinants of acidity in regards to the periodic table
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within a row, the more electronegative an atom, the more acidic it is. So F is more acidic than O and N. In a column, atomic size does because the larger the atom the better it displaces negative charge and the weaker the bond.
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what is an oxyacid?
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The acidic H is bonded to an O, which in turn is bonded to a central atom. The simplest rule is that the more O atoms there are bonded to a central atom, the more O atoms withdraw electron density from central atom, and thus the more acidic the oxyacid.
As a rule, for every extra O on the central atom, the pKa of the acid will drop by app 5 pKa units. |
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when determining strength of an oxyacid, what should you consider?
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number of excess oxygens and electronegativity. The stronger the acid, the more oxygens and the more electronegative the central atom.
the answer is B. Asking for weakest acid |
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what is the pKa of carboxylic acid, phenol, and ammonium cation?
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What is a polyprotic acid?
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An acid that yields multiple equivalents of hydronium ion when treated with a base (H3O+). the most common examples are H2CO3, H2SO4 and H3PO4. Often described in terms of NORMALITY (moles of equivalents/liter). Polyprotic acids have multiple pKa, for every H, and the first H that is removed is the most acidic, etc.
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what is a diprotic amino acid?
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an amino acid that does not have a an active proton on the side chain
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what is a triprotic amino acid?
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has 1 active proton on the side chain
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What is Normality
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The moles of equivalents per liter. Another way is multiply molarity by number of protons per molecule. Ex: A 1.0 molar diprotic acid solution would be listed as 2.0 normal because there are 2 equivalents of acid.
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In a polyprotic acid, in H2CO3 for example, which pKa correstponds to which pKb
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pKa1 corresponds to pKb2, and pKa2 corresponds to pKb1. This is because the first proton lost is the second proton gained by the conjugate base. The conjugate base combines with the less acidic proton first and then the most acidic proton!
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Log of 2
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.3
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log of 3
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.48
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When solving -log of 2 X 10-3, what would you simplify to?
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3- log 2
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what is the short cut equation to find the pH of weak acids
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Given that the Ka is smaller than the given concentration and the pKa lies between 2 and 12
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Typical conjugate pairs
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(RCO2H/RCO2-), (RNH3+, RNH2), (C6H5OH/C6H5O-), (H2CO3/HCO3-), (H3PO4/H2PO4-)
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How are pH and pKa related
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The pH refers tot he surrounding solution (environment) in which the compound exists. The pKa refers tot he conjugate acid that exists in solution. The compound responds tot he pH of the solution.
Carboxylic acids have pKa values of 2 to 5, ammonium and alkyl ammoniums have pKa values of 9 to 11. |
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What is the pKa for ammonia, given that the pKb for ammonia is 4.7
A. 4.7 B. 7.0 C. 9.3 D. 33 |
If you don't fall for the trap, then the answer is obviously 33. NH3 is a weaker acid than NH4+, and the pKa for NH4+ is 9.3 (given the pKb for its conjugate base, NH3, is 4.7), therefore, the pKA for NH3 must be greater than 9.3. Since there is only 1 answer choice greater than 9.3, that's the answer - D.
pKa and pKb=14 only for conjugates...not for the same compound. That is why pKa and pKb don't add up here. |
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henderson hasselbach equation in moles is here.
What is it using concentrations? |
Used when calculating the pH of both components in a weak conjugate pair.
This means that the addition of water has no effect on pH, even when the compounds are diluted. |
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How do impurities raise boiling point and lower freezing point in aqueus solution? Like adding NaCl?
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They interact with the water which makes it more difficult for water molecules to break loose and evaporate or form an orderly crystal lattice while freezing. The more impurities, the ligher/lower the boiling/freezing point. So for weak acids, the more it dissociates, the more impurities are in solution.
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When .1 moles of an unknown weak acid HA are dissolved into 100 mL of H2), the pH for the solution is 3.7. What is the concentration of its conjugate base (A-)?
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When an acid dissociates, equal parts of hydronium ion are formed. You know that [H30+]=[A-]. The pH of the solution is 3.7, so [H3O+] is 10^-3.7.
This breaks down to 10^-4 + 10^.3 10^.3 is 2. So, the answer is 2*10^-4. (remember this relationship from log) |
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what is the question asking for when it is asking for the "which acid yields the greatest concentration of conjugate base?"
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It's asking for the strongest acid
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What is the question asking for when it asks "in the series, which is true for the acid that has the greatest Ka value?"
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Again, it is asking for the acid that undergoes the most dissociation....the strongest acid.
Be able to recognize what the questions are asking for and the different ways they can ask for a strong acid. |
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What is the pH in distilled water if the [OH-] = 1X10^-6?
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pH=6 because in distilled water the amount of [OH-]=[H3O+]
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If 10 mL of an acqueous solution of a stong acid with pH=2 were mixed with 100 mL of pure water, then the final pH value would be?
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Greater than 3. Why? A change in volume from 10 to 110 is 11 fold. log of 10=1. So the pH increases by a little more than 1.
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When looking at current readings of KOH and KOAc, why are their readings similar?
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KOAc is a weakly basic salt. What do we know about salts? They all completely dissociate in water. So both KOH and KOAc dissociate completely, when though they have different basicities.
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Oxalic acid
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HO2CCO2H, or H2C2O4
A DIPROTIC weak acid |
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Ideal gas law
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PV=nRT
n=.0821L*atm*mole^-1*K^-1 |
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if pH>pKa, then how do [H+] and Ka relate to one another
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[H+]<Ka because the p stands for -log.
pH=-log[H+] pKa=-log of Ka |
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What is a monometer?
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It measures the difference of pressures of different gases by looking at the height differences that occur when 2 gases are present. Mercury is the medium by which we look at height differences.
Delta Pressure=density*gravity*delta height |
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what are the units for the gas constant .0821?
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L*atm/mol*K
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what are the units for the gas constant 8.31?
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J/mol*K
Use if vol=m^3 and pressure = Pascal =N/m^2 J=N*m 1atm is about 100kPascal or 101.35kPA exactly m^3 = 1000L |
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root mean squared of speed of gas particle
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R=8.31 J/mol*K
T= temp in Kelvin m=mass in kg |
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what is the relationship between mass and velocity when comparing 2 gases
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what is the relationship between velocity and temperature when comparing 2 gases
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Describe Effusion
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It's the process of gas escaping from the region within a container to the environment outside the container through pores
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Describe Infusion
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the reverse of effusion. It involves a gas entering a container through the pores of its walls.
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what is P and X when discussing disfusion/effusion/infusion of gases
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P=absolute pressure
X=relative abundance |
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Gibbs free energy equation
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Gibbs=change in enthalpy - T change in entropy
in Kelvin |
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The complex and stupid gibbs free energy equation
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Gibbs=RTln(Qrx/Keq)
As the ratio decreases, there are more reactants than products, ln of anything less than 1 is a negative number and gibbs favors the forward reaction. |
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what is the bond energy of the second pi bond in nitrogen gas
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In this case they are asking for the energy difference between the 2 pi bonds, the double and triple bond. He knew?
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Difference between SN1 and SN2 reaction
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Sn2 need a strong nucleophile because the halogen leaves at the moment nucleophile attacks the partially positive electrophile. The nucleophile can only attack opposite side of the leaving group. It is called a SN2 because it is bimolecular, depends on the concentration of both nucleophile and electrophile.
SN1, the leaving group leaves and leaves an electrophile (a cation) and THEN the nucleophile attacks. It's a SN! because it is unimolecular, the rate only depends on on concentration of alkyl halide |
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Is a first-order reaction associative or dissociative?
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dissociative
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Is a second order reaction dissociative or associative?
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associative
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