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55 Cards in this Set
- Front
- Back
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Polyatomic ions
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Composed of several atoms
Joined by covalent bonds Retain a definite charge when dissociated from the complementary ion Includes both anionic (-) * cationic (+) polyatomic ions |
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Water (dissolved) compounds of polyatomic ions
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Caused by the polarity of water molecules
Orient themselves so the electronegative part (O) faces the cation (H), which stabilizes it H atoms surround the O atoms, making its charge less effective |
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Steps toward water purification
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Precipitation of solids
Aluminum sulfate + lime = aluminum hydroxide gel (traps suspended particles) Pathogens are eliminated (chlorination, UV, or ozone treatment) Flourination Iodinization |
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Hard water
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Water that contains at least 250ppm of combined calcium & magnesium
Amount depends on rock types in the reservoirs Amount measured by titration |
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EDTA
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Compound that traps calcium in the process of measuring levels of calcium & magnesium in hard water
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Chromatograph
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Any lab technique used to separate mixtures
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Distillation
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A method of separating mixtures based on differences in their volatilities
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Reverse osmosis
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A separation process that uses pressure to force a solution through a membrane
Retains the solute on one side and allows the pure solvent to pass to the other side |
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Acids
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The substances that release H+ cations when dissolved in water
Results in a free-charged proton, which is unstable (reactive) in water Combines with water to make the hydronium cation H3O+ |
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Strong acids
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Acids that dissociate completely in water
No acid molecule is left intact after dissolution |
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Weak acids
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Acids that partially dissociate until an equilibrium state is reached
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Bases
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Substances that when dissolved in water dissociate and release hydroxide (OH-) anions
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Neutralization
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The process by which an acid & a base combine in a solution to neutralize each other
H+ and OH- will combine with each other to form water, and the other ions will remain in solution |
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Acidity/baseness of water
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Since we use the dissolution of substances in water as definition, water is neither acidic nor basic
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Acidity scale
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If M(H)+ > M(OH)- , then the solution is acid
Acids have higher concentrations (less negative numbers) so pH<7 is acid If M(H)+ < M(OH)- , then the solution is basic Bases have lower concentrations (more negative exponents) so pH>7 are basic |
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Anhydrides
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Oxides without water
Combined with water, these yield acids which, in turn, will dissociate & provide H+ to the water |
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pH of rain water
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Slightly acidic (pH = ~6)
In the case of CO2, the resulting acid (H2CO3) is very weak and only dissociates in 1% of the molecules Acidity is primarily caused by SO(x) & NO(x), which react with water to produce H+ ions |
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Isotopes
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Forms of the same atom, only with different numbers of neutrons
Every atom in the periodic table is present in nature as 2+ isotopic forms Depending on the ratio of neutrons to protons, these can be stable or unstable (radioactive) |
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Radioactivity
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When an isotope isn't stable
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Fission
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A reduction in the number of neutrons
Caused by instability in the isotope The process of splitting the isotope Results in a stable atom with fewer neutrons |
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Radioactive decay
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A method of reducing the number of neutrons in an isotope
Caused by alpha and beta emissions |
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Uranium isotopes
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Uranium-235 is bombarded with isotopes to transform into Uranium-236
Decomposes into Barium-141, Krypton-92, and 3 neutrons When Uranium-235 splits due to neutron bombardment, 0.1% of the original mass “disappears” because of Einstein’s equation: -E = m x C^2 The energy produced the fission of 1 kg of uranium is enormous (9 x 10^13 J) |
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Alpha radioactive emissions
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Comprised of 2 protons and 2 neutrons
Charge of +2 Cause the element to transform into another atom that’s an atomic number equal to the original atomic number minus 2 Example: U-238 transforms into Th-234 and He-4 In this case, U-238 is the parent atom, and Th-234 is the daughter atom |
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Beta radioactive emissions
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Comprised of one electron
Carries a charge of -1 One electron leaves the parent atom, so the daughter atom contains one extra proton Example: Th-234 devolves into Pa and one electron This is possible because the origin of the electron is the decomposition of a neutron |
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Gamma radioactive emissions
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Comprised of one photon of energy
Carries no charge |
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Decay series
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Whenever decay occurs, the resulting elements will continue decaying until they finally reach a stable (non-radioactive) isotope which will be the final product
The routes are not unique, but the end result is |
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Subproduct of the reaction of Plutonium-239
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Effective in creating bomb material
Highly toxic when exposed to air Requires a high level of sophistication to isolate |
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Chernobyl Nuclear Power Plant
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Control rods were graphite, which will catch fire and produce an explosion at high temperatures
No reinforced dome allowed the top of the reactor to open and spew the radioactive material propelled by the internal fires Water is primary cooling material |
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Radioactive occupational hazards
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Highly possible from coal-mining accidents and black lung disease
Virtually impossible from nuclear-powered electricity generation |
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Catastrophic, non-occupational hazards
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Fairly possible from acute air pollution because of coal-powered electricity generation
Fairly impossible from nuclear-powered electricity generation |
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General environmental degradation
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Possible in coal electricity production because of strip mining, acid runoff, and acid rainfall
Possible in nuclear electricity because of long-term contamination with radioactivity |
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Routine population hazards
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Relatively high in coal electricity production because of air pollution
Relatively low in nuclear electricity production because of radioactive emissions |
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Rad
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Abbreviation for radiation absorbed dose
Equal to 0.001 Joule per Kg of tissue Doesn’t aptly represent the damage it can cause |
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Rem
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Abbreviation for roentgen equivalent to mammals
The rad times the multiplier |
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Sources of radiation
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Natural (82%) - primarily radon (55%)
Man-made (18%) - primarily medical X-rays (11%) |
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Long-term effects of radiation
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Examples:
Tumors Infertility Birth defects in offspring |
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Uses for radiation in medicine
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Examples:
X-rays Magnetic radiation |
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Radioisotopes
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Atoms with unstable nuclei
Can be used for diagnostic or treatment In diagnostic uses a particular inorganic element that is used in biological processes is introduced into the patient and allowed to interact with the target organ After a certain period of time the area where the organ is located is scanned with a radiation sensitive probe and imaging of the target can be produced Radioisotopes can be used for targeted therapy to a certain type of cells by either introducing an element with very high affinity to those cells or by attaching the isotope to an antibody designed to distinguish that particular cell type |
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Thyroid scan
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Typical example of a use of Iodine-131 in medicine
Used to locate irregularities in the thyroid gland Scan can be static (one shot) or dynamic (multiple shots) |
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Radiation therapy
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An external source of radiation
Different from radioisotopic therapy in that there is no introduction of radioisotopes to the body Produces a beam of radiation that is applied to the patient in the affected area |
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X-rays
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They are a form of non-particulate radiation (as gamma rays) that easily transverse the soft tissues in the body but it is absorbed by the inorganic component of bones
As such, they are very useful in the determination of skeletal abnormalities / injury |
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Computer Assisted Tomography (CAT) Scans
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A series of x-rays plates that are produced with radiation of a lower intensity that an x-ray
This allows for the soft tissues to be visualized due to the different rate of absorbency they exhibit to radiation in response to the mineral content in them |
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Nuclear magnetic resonance
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The highest level of resolution that we can obtain with non-invasive procedures
Based in the fact that all nuclei of all atoms produced a low level magnetic field by their rotating nature The principle is that, when you apply a magnetic field equal to that of the nucleus, they will enter in resonance and their intensity will be amplified |
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Hydrogen as an ideal fuel
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Burning H2 gives the best yield in energy per gram of fuel that can be obtained
No pollutants are released, only water vapor Very difficult to obtain in large quantities Energetic cost is still uneconomical Difficult storage and transport (storage can be solved by absorbing H2 into alkaline metals) |
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Fuel cells
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An electrochemical conversion device
H2 without the danger Any electrochemical (redox) reaction involves a reduction hemireaction and an oxidation hemireaction Reductions involve the aceptance of e- by an atom Oxidations involve the donation of e- by an atom The hydrogen donor can be an hydrogenated compound as methanol, which solves the problem of production and storage of H2 |
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Batteries
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They operate on the same principle as a fuel cell (redox reactions) without the fuel.
The reaction is sealed in two compartments that produce the reduction (cathode) and oxidation (anode). If the reaction involves the same element, then the battery can be recharged by passing electricity through the cell in the reverse direction from the spontaneous process. |
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Pure water
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Free from pathogens — not necessarily pure H2O
Proves that water is an excellent solvent |
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Solvent
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A substance that dissolves other substances
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Solution
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homogeneous mixture of uniform composition
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Ppm and ppb
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Parts per million or billion are used to express very low concentrations
Weight units are always used |
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Molarity
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The number of moles per liter of solution
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Polarity
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The dipole-dipole intermolecular forces between the slightly positively-charged end of one molecule to the negative end of another or the same molecule
Dependent on the difference in electronegativity between atoms in a compound and the asymmetry of the compound's structure |
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Ions
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Particles that maintain a definite charge when dissociated
All salts are ionic solids, where the energy of union is provided by electrostatic attractions between positively and negatively charged particles |
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Cations
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Positively charged ions
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Anions
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Negatively charged ions
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