Chapter 14: Solutions

Question 1

Solution

Answer 1

Homogenous mixture of two or more substances

Question 2

Solvent

Answer 2

Major component in solution

Question 3

Solute

Answer 3

Minor component in solution

Question 4

Aqueous Solution

Answer 4

• Water is solvent

Question 5

Solubility

Answer 5

Amount of substance that will dissolve in given amount of solute

Question 6

Entropy

Answer 6

• Measure of energy randomization/dispersal in a system - Tendency is for energy to spread out/disperse whenever unrestrained

Question 7

Intermolecular Forces

Answer 7

• Dispersion: Weak - Dipole-Dipole: Separation of charges lead to electrostatic attraction - Hydrogen bond: Observe what H is bonded to; different in electronegativity - Ion dipole: Electrostatic force between ion and neutral molecule with dipole

Question 8

Solution Interactions

Answer 8

• Solute-Solvent: Interactions between solvent particles and solute particles - Solvent-Solvent: Interactions between solvent particle and another solvent particle

Question 9

Interactions and Formation

Answer 9

• Solvent-Solute > Solvent Solvent and Solute-Solute Interactions = Solution Formation - Solvent-Solute = Solvent-Solvent and Solute-Solute = Solution formation - Solvent-Solute < Solvent-Solvent and Solute-Solute = may or may not form

Question 10

Polar Solvent Examples

Answer 10

• Water, acetone, methanol, ethanol

Question 11

Non polar solvent examples

Answer 11

• hexane, diethyl ether, toluene, carbon tetrachloride

Question 12

Hess’s Law

Answer 12

Overall enthalpy change upon solution formation is sum of enthalpy ∆Hsoln = ∆Hsolute + ∆Solvent + ∆Hmix (endothermic) - If ∆Hmix is more than the remaining, heat of solution is negative (exothermic)

Question 13

Heat of Hydration

Answer 13

• Enthalpy change when 1 mol of gaseous solute ions are dissolve in H2O - Typically negative ∆Hsoln = ∆Hsolute + ∆Hydration - Take absolute value of ∆Hsoln and ∆Hhydration to compare; if solute is more, amount of E to separate solute into constituent ions is less than energy given off when an ion is hydrate (process is exothermic)

Question 14

Dynamic Equilibrium

Answer 14

• Rates of dissolution and recrystallization become equal

Question 15

Saturated solution

Answer 15

• Solution in which dissolved solute is in dynamic equilibrium with solid solute (undissolved)

Question 16

Unsaturated solution

Answer 16

Solution containing less than equilibrium amount of solute

Question 17

Supersaturated solution

Answer 17

One containing more than equilibrium amount of solute; often unstable and excess solute precipitates out

Question 18

Effect of temperature on solids in H2O?

Answer 18

• Solubility of most solids in water increases with increasing temperature

Question 19

Factors affecting solubility of gases in H2O?

Answer 19

• Temperature: Solubility of gases in liquids decrease with increasing temperature - Pressure: Higher the pressure of a gas above a liquid, the more soluble it becomes

Question 20

Henry’s Law

Answer 20

Sgas = kHpgas

Question 21

Dilute solution

Answer 21

Contains small quantities of solute relative to amount of solvent

Question 22

Concentrated solution

Answer 22

Contains large quantities of solute relative to amount of solvent

Question 23

Molarity

Answer 23

(M) amount of solute (mol) / volume solution (L)

Question 24

Molality

Answer 24

(m) amount solute (mol) / mass solvent (kg) - Temperature independent

Question 25

Mole fraction (X)

Answer 25

amount solute (mol) / total amount solute + solvent (mol)

Question 26

Mole %

Answer 26

amount solute (mol) / total amount solute + solvent (mol) x 100%

Question 27

Parts by mass

Answer 27

mass solute / mass solution x multiplication factor

Question 28

Colligative properties

Answer 28

Properties that depend on number of particles dissolve in solution

Question 29

Vapor Pressure Lowering

Answer 29

VP of liquid = P of gas above the liquid when the two are in dynamic equilibrium

Question 30

Raoult's Law

Answer 30

Psolution = XsolventP˚solvent

Question 31

Two Component Solution

Answer 31

P_A = X_AP˚_A P_B = X_bP˚_B Total Pressure = Ptot = P_A + P_B

Question 32

Nonideal Solution

Answer 32

- Solute-solvent interactions are either stronger or weaker than solvent-solvent interactions - If solute-solvent stronger: Solute tends to prevent solvent from vaporizing readily - Solution is dilute: Effect = small - Solution is not dilute = effect is significant

Question 33

Freezing Point Depression

Answer 33

∆T_f = m x K_f ## Footnote - Tf = change in temp in celsius - m = molality - Kf = freezing point depression

Question 34

Osmosis

Answer 34

- Flow of one solvent from solution of lower solute concentration to one of higher concentration

Question 35

Semipermeable Membrane

Answer 35

- Membrane that selectively allows some substances to pass through but not others

Question 36

Osmotic Pressure Equation

Answer 36

π = MRT ## Footnote - M - molarity - T - Temperature in Kelvin - R - Ideal gas constant (0.08206...)

Question 37

van Hoff Factor

Answer 37

- (i) Ratio of moles of particles in solution to moles of formula units dissolved i = moles of particles in soln. / moles formula units

Question 38

van Hoff Factor Equations

Answer 38

∆Tf = im x Kf ∆Tb = im x Kb π = iMRT