Chapter 12

Question 1

Solubility

Answer 1

Amount of the substance that will dissolve in a given amount of solvent.

Question 2

Aqueous Solutions

Answer 2

Water is the solvent. Gas, liquid, or solid are the solvent.

Question 3

Entropy

Answer 3

A measure of energy randomization or energy dispersal in a system.

Question 4

Miscible

Answer 4

Substances that are soluble in each other in all proportions

Question 5

Enthalpy of Solution (∆Hsoln)

Answer 5

The sum of the changes in enthalpy for each step. (i) If the sum of endothermic terms is about equal in magnitude to the exothermic term, then ∆Hsoln is about zero. (ii) If the sum of endothermic terms is smaller in magnitude than the exothermic term, then ∆Hsoln is negative and the solution process is exothermic. (iii) If the sum of endothermic terms is greater in magnitude than the exothermic term, then ∆Hsoln is positive and the solution process is endothermic.

Question 6

Heat of Hydration [∆H(hydration)]

Answer 6

The enthalpy change that occurs when 1 mol of gaseous solute ions are dissolved in water.

Question 7

Dynamic Equilibrium

Answer 7

The point at which the rate of the reverse reaction equals the rate of the forward reaction.

Question 8

Saturated Solution

Answer 8

A solution in which the dissolved solute is in dynamic equilibrium with any undissolved solute; any added solute will not dissolve.

Question 9

Unsaturated Solution

Answer 9

A solution containing less than the equilibrium amount of solute; any added solute will dissolve until equilibrium is reached.

Question 10

Supersaturated Solution

Answer 10

A solution containing more than the equilibrium amount of solute

Question 11

Solubility of Gases

Answer 11

-Decreases with increasing temperature. -The higher the pressure of gas above a liquid, the more soluble the gas in the liquid.

Question 12

Henry’s Law

Answer 12

Expresses the relationship between solubility of a gas and pressure: S(gas)=K(h)*P(gas)

Question 13

Dilute Solution

Answer 13

Solution containing small quantities of solute relative to the amount of solvent.

Question 14

Concentrated Solution

Answer 14

Solution containing large quantities of solute relative to the amount of solvent.

Question 15

Molarity (M)

Answer 15

The amount of solute (moles) per volume of solution (L)

Question 16

Molality (m)

Answer 16

The amount of solute (moles) per mass of solvent (kg)

Question 17

ppm

Answer 17

(Mass Solute/Mass Solution) x 10^6

Question 18

ppb

Answer 18

(Mass Solute/Mass Solution) x 10^9

Question 19

Mole Fraction

Answer 19

Amount of Solute (moles) per total amount of solute + solvent (in moles).

Question 20

Mole Percent

Answer 20

Mole Fraction x 100%

Question 21

Colligative Property

Answer 21

-A property that depends on the number of particles dissolved in a solution, not on the particle type. -Four Types: (1) Vapor Pressure Lowering (2) Freezing Point Depression (3) Boiling Point Elevation (4) Osmotic Pressure

Question 22

Vapor Pressure Lowering

Answer 22

The difference in vapor pressure between a pure solvent and a solution of the solvent. ∆P=P°(solvent) - P(solution)

Question 23

Freezing Point Depression

Answer 23

The effect of a solute that causes a solution to have a lower melting point than the pure solvent.

Question 24

Boiling Point Elevation

Answer 24

The effect of a solute that causes a solution to have a higher boiling point than the pure solvent. Note: BP of a solution containing nonvolatile solute is higher than the BP of the pure solvent.

Question 25

Osmotic Pressure

Answer 25

The pressure required to stop osmotic flow.

π=MRT, T= 0.08206 L*atm/mol*K

Note:

*Osmosis: flow of solvent from a solution of lower concentration to one of higher concentration.

*Semipermeable Membrane: membrane that selectively allows select substances to pass through-separates two half of a cell.

Question 26

van’t Hoff factor (i)

Answer 26

(moles of particles in solution) / (moles of formula units dissolved)

Question 27

Henry’s Law

Answer 27

An equation that expresses the relationship between
solubility of a gas and pressure:

S_gas=K_HP_gas

Question 28

Molarity (M)

Answer 28

M= Moles of Solute / Volume of Solution

Unites mol/L

Question 29

Concentrations of Solutions

Answer 29

• Percent by Mass = (Mass of solute x 100%) / (Mass of Solution)
• ppm = (Mass of solute x 10⁶) / (Mass of Solution)
• ppb = (Mass of solute x 10⁹) / (Mass of Solution)

Question 30

Mole Fraction (X)

Answer 30

X_solute = (n_solute) / (n_solute + n_solvent)

Question 31

Mole Percent

Answer 31

Mol % = X * 100%

Question 32

Raoult’s Law

Answer 32

An equation used to determine the vapor pressure of a
solution:

P_solution = X_solventP°_solvent

Question 33

Vapor Pressure of a solution with volatile components

Answer 33

P_A = X_AP°_A

P_B = X_BP°_B

P_total = P_A + P_B

Question 34

Molality (m)

Answer 34

(moles solute) / (mass solvent)

Units :mol / kg

Question 35

Freezing Point Depression

Answer 35

(∆T_f) = m*K_f

Question 36

Boiling Point Elevation

Answer 36

∆T_b = m*K_b