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EK Chem 4
Solutions
| Question | Answer |
|---|---|
| solution | homogenous mixture of 2+ compounds in a single phase |
| ideal solution | solutions made from cmpds that have similar properties (cmpds can be interchanged w/in the soln w/o changing spatial arrangement of molecules/intermolecular interactions |
| ideally dilute solution | solute molecules are completely separated by solvent molecules so that they have no interaction w/ each other [mole fraction of solvent is approx 1] |
| nonideal solutions | not ideal, or ideally solute (cmpds are not similar, and solute molecules interact with each other) |
| colloid | like a soln, only the solute particles are larger, but too small to be extracted by filtration but large enough or charged enough to be separated by semipermeable membrane; will scatter light; can be attracted/repelled by dispersion medium |
| molarity | (M) moles of solute/volume of solvent |
| molality | (m) moles of solute/kg of solvent |
| mole fraction | (x) moles of solute/total moles o% |
| mass % | mass of solute/total mass of soln * 100 |
| ppm | mass of solute/total mass of soln * 10^6 |
| normality | # equivalents/liter of solution |
| steps of solution formation | 1. breaking of intermolecular bonds btw solute molecules 2. breaking of intermolecular bonds btw solvent molecules 3. formation of intermolecular bonds btw solvent and solute molecules |
| if overall soln formation releases energy, it is an ____ rxn | exothermic |
| exothermic soln formation results in | the new intermoleclar bonds are more stable then the old and in general, the intermolecular attractions w/in soln are stronger than w/in the pure substances |
| if overall soln formation absorbs energy, it is an ____ rxn | endothermic |
| endothermic soln formation means.. | intermolecular attractions in the pure substances are stronger than the intermolecular attractions in the soln |
| solution formation has positive or negative entropy? | positive bc the combined misture is more disordered than the separated pure substances |
| vapor pressure | pressure created by the molecules in the open space when the rate of molecules leaving the liquid equals the rate of molecules entering the liquid is equal the rate of molecules leaving the liquid |
| vapor pressure is a function of ___ | tempearture - VP will increase with temperature |
| vaporization is endothermic or exothermic? | endothermic |
| boiling occurs when... | the vapor pressure of the liquid equals the atmospheric pressure |
| melting occurs when.. | the vapor pressure of the solid phase equals the vapor pressure of the liquid phase |
| what is a nonvolatile solute? | solute with no vapor pressure |
| raoult's law for nonvolatile solutes | describes the vapor pressure of the solution, and is proportional to the mole fraction of the liquid a and the vapor pressure of the pure liquid Pa Pv = XaPa |
| volatile solute | solute with vapor pressure |
| raoult's law for volatile solutes | Pv = XaPa + XbPb |
| how does the vapor pressure of nonideal solutions relate to heats of solution? | negative heats of solution form stronger bonds and will have lower Pv,; positive heats of solution form weaker bonds and raise Pv |
| what does the graph deviation look like for the vapor pressure of a nonideal solution with a positive heat of solution? | positive deviation - concave down |
| what does the graph deviation look like for the vapor pressure of a nonideal solution with a negative heat of solution? | negative deviation - concave up |
| the higher the vapor pressure of a liquid at a given temperature, the ___ the normal boiling point | lower |
| solubility product | equilibrium constant of a solvation reaction; changes only with temperature |
| solubility | maximum number of moles of the solute that can dissolve in solution; depends upon the temperature and the ions in solution |
| solubility rule 1 | nearly all ionic cmpds with nitrates, ammonium, and alkali metals are soluble |
| solubility rule 2 | ionic cmpds with halogens are soluble except when with silver, mercury, or lead |
| solubility rule 3 | sulfate cmpds are soluble except when with mercury, lead, and heavier alkaline metals (Ca2+, Sr2+, Ba2+) |
| solubility rule 4 | cmpds with heavier alkaline metals (Ca2+, Sr2+, Ba2+) are soluble when paried with sulfides and hydroxides |
| solubility rule 5 | carbonates, phosphates, sulfides, and hydroxides are generally insoluble except when with heavier alkaline metals |
| common ion effect | an ion common to an ion in the equilibrium will disturb it; if added to a saturated solution, it will shift the equilibrium increasing precipitate; if added to a soln that is not saturated, it will NOT shift equilibrium |
| factors affecting solubility of gases | mostly pressure and temperature, but also its size, and reactivity with the solvent |
| pressure on a gas ____ its solubility | increases |
| as temperature increases, the solubility of salts generally _____ | increases |
| henry's law | solubility of gas is proportional to its vapor partial pressure. (in an ideally dilute solution) C = ka1*Pv where C is the solubility of gas a, ka1 is henry's law constant which depends on solute-solvent pair |
| alternate henry's law equn | Pv = Xa*ka2 where Xa is the mole fraction of a in a soln and ka2 is henry's law constant (diff then ka1) |
| raoult's law is most accurate when ... | looking at vapor partial pressure of a solvent with high concentration |
| henry's law is more accurate when.. | looking at the vapor partial pressure of a volatile solute where the solute has low concentration |
| as temperature increases, the solubility of gases generally ____ | decreases |
| are heavier gases more or less soluble? | tend to be more soluble bc heavier/larger gases experience greater VDW forces |
| gases that react chemically with a solvent have a ______ solubility | greater |
Created by:
miniangel918
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