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69 Cards in this Set
- Front
- Back
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in solids, is the energy of attraction greater than or less than kinetic energy |
greater than |
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describe the difference between intra and inter molecular forces |
intra is bonds in molecules and is stronger than inter, inter is weak molecular attractions between molecules |
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what are the 3 types of intermolecular attractions between electrically neutral molecules? |
dispersion (or london) forces, dipole-dipole forces, hydrogen bonding |
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describe dispersion forces? |
attractions between an instantaneous dipole and induced dipole. present in ALL polar and non polar molecules. |
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what is polarizability? |
the tendency of e- cloud to distort in a way dispersion forces are present. |
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what factors effect dispersion forces? |
increase with increasing atomic or molecular size, increase in strength with increasing molecular weight, long skinny molecules tend to have stronger dispersion forces than short fat ones |
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what intermolecular forces exist between HBr, CH4, and SO2? |
HBr, dispersion forces, dipole-dipole CH4, dispersion forces SO2, dispersion forces, dipole-dipole |
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what group has the lowest weight and boiling point? |
4A |
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what are hydrogen bonds? |
attraction between H to highly electronegative atom (typically O,N,F) |
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describe ion-dipole interactions |
positive end of polar molecules to neg. charged anion Neg. end of polar molecule to positively charged cation. This is how ionic substances dissolve in polar solvents. |
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when molecules have a comparable weight and shape, intermolecular forces differ due to |
differences in strength of dipole-dipole interactions or hydrogen bonds. |
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when molecules have different molecular weight and no hydrogen bond, intermolecualr forces differ due to |
dispersion forces |
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a dipole-dipole intermolecular force indicates |
a polar molecule |
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which is a stronger intermolecular force, a dipole-dipole or a hydrogen bond |
hydrogen bond |
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how does intermolecular force impact volatility? |
the lower the intermolecular force, the more volatile it is |
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intermolecular attractions and strength of the following molecules: Cl2, HF, F2, SO2, BaCl2 |
Cl2 dispersion HF Dispersion, dipole-dipole, Hydrogen bonding BaCl2 dispersion, ionic bonding F2 dispersion F2, Cl2, SO2, HF, BaCl2. |
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how does intermolecular force influence boiling point? |
stronger and higher the intermolecular force indicate a high boiling point. if all elements have same forces, highest boiling point determined by dispersion |
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describe viscosity |
resistance of a liquid to flow increases with stronger intermolecular forces decreases with higher temperature inceases with molecular weight Kg/Cm-s |
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describe surface tension |
a measure of the net inward force that must be overcome to expand the surface area of a liquid is given by its surface tension |
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what are cohesive forces |
intermolecular force that binds similar molecules together |
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what are adhesive forces |
bind substances to surface |
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describe capillary action |
rise of liquids up a narrow tube, only when the adhesive forces are stronger than cohesive forces, creating an inbalance. capillary action is stopped when gravity balances adhesive forces |
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bottom line for viscosity is |
higher intermolecular forces mean higher viscosity |
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order the following in increasing viscosity CH2Cl2, CH3CH2CH3, CH3CH2OH |
CH3CH2CH3, CH2Cl2, CH3CH2OH |
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describe the heat of fusion |
the energy required to change a solid at its melting point to a liquid |
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describe the heat of vaporization |
the energy required to change a liquid at its boiling point to a gas |
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What is deposition |
gas to solid |
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what is sublimation |
solid to liquid |
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what is the heat of sublimation? |
the energy required to move solid particles directly into the gaseous state |
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what is the critical temperature? |
the highest temperature a liquid can exist |
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what is a heating curve |
graph of temperature vs. amount of heat added. |
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during a phase change does the temperature of a substance rise? |
no |
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what is dynamic equilibrium? |
liquid molecules evaporation and vapor molecules condensation is at the same rate |
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how does temperature effect vapor pressure? |
it increases it |
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describe boiling point of a liquid |
the temperature at which its vapor pressure equals the environmental pressure surrounding the liquid. |
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what is the normal boiling point? |
the temperature at which its vapor pressure is 760 torr (1atm) |
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how do intermolecular forces effect vapor pressure? |
stronger intermolecular forces indicate lower vapor pressure. |
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order the following in increasing vapor pressure. CH2Cl2, CH3CH2CH3, CH3CH2OH |
CH3CH2OH, CH2Cl2, CH3CH2CH3 |
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what is the version of clausius claeyran equation that will be used? |
ln (P2/P1) = (-heat of vaporization / R (8.314)) x(1/T2 - 1/T1) |
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what do the equilibrium lines in a phase diagram show? |
liquid to vapor, solid to liquid, and solid to gas interfaces. |
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what is the point on a phase diagram where all three phases are in equilibrium? |
the triple point (T) |
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what happens above the critical point in a phase diagram? |
liquid and vapor are indistinguishable from each other. |
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what is a liquid crystal? |
a substance that exhibits one or more ordered phases at a temperature above the melting point of the solid |
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describe the line ups of nematic and sematic A crystals. |
Nematic liquid crystals line up except for the ends, Semaic A lines up perpendicular. |
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what are the two points of formation of solution? |
natural tendency of substances toward mixing. types of intermolecular interactions involved in the solution process. |
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describe the spontaneos process of mixed gasses? |
little intermolecular interaction. molecular motion --> spread. favored by the increase in entropy. |
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describe solute-solute interactions |
dispense the solute particles |
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describe solvent-solvent interaction |
must be overcome, make room |
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describe solvent-solute interactions |
this is solvation and it occurs once solvent-solvent interactions are overcome. |
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in the following equation what parts are always positive and what parts are always negative? Heat of solution = heat of solute plus heat of solvent plus heat of mix |
heat of solute + heat of solvent will always be positive. Heat of mix will always be negative. |
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describe dissolution? |
this is a physical process, you get back the origional solute. |
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under what conditions will a solute not dissolve in a solvent? |
if solvent-solvent interactions are stronger than solute-solvent interactions |
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when a solution if formed, does entropy increase or decrease? |
increase |
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a solute will dissolve in a solvent if...? |
solute-solvent interactions balance the sum of solute-solute and solvent-solvent interactions. |
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describe crystallization |
as the dissolution continues, solute particles will reattach. |
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define saturated solution |
no additional solute will dissolve |
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what is solubility? |
the amount of solute needed to form a saturated solution in a given quantity of solvent. |
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what is unsaturated? |
dissolved less solute than the amount needed to form a saturated solution. |
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what is supersaturated? |
solution that contains a greater amount of solute than needed |
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what can occur with unstable solutions? |
can obtain crystallization by adding a seed crystal or scratching the side of the glass |
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what does the phrase "like dissolves like" imply? |
polar solvents dissolve polar solutes. nonpolar solvents dissolve nonpolar solutes. |
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C6H14 is one of many nonpolar carbohydrogen chains called |
hexane |
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how do OH groups effect hydrocarbons? |
as the length increases, the OH group becomes small part of molecule, and the molecule acts as a nonpolar hydrocarbon |
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how does pressure effect solubility? |
it does not change it appreciably. |
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solubility of a gas in a liquid is...? |
directly proportional to its pressure. |
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what is the equation for henrys law? |
Solubility of gas equals a constant times the pressure of the gas |
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what is the equation based on henrys law we use to compare two different pressure solubility ratios? |
S1/P1 = S2/P2 |
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how does temperature effect the solubility of a solid? |
as temperature increases, solubility increases |
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how does temperature effect solubility of a gas? |
as temperature increases, solubility decreases. |
