Question

XA WinAna): Molarity: M e (mole)/Volume of solution in L), molality me molemas oletne Raoult's law: PAXA PA' AT, kim; AT. - kom - CRT (Gas constant R0.08206 atm-/mol; Henry's law. of gas = k. Per In (p/p) -(AH/R) (1/T2-1/T.): 1 atm = 760 mm He: Avogadro's number: 6.022 x 10" Part 1. Multiple choice problems (45 points: 5 points for each question) 1. Which of the following gases and pressures will result in the greatest as solubility in 1 water at 25°C a) 1-atm CH,Cl gas b) 2-atm CH,Cl gas c) 1-atm CHe gas d) 2-atm CHegas ) none of bove 2. Based on the normal boiling point of NH) (-33.3 "C) and SbH(-17.0°C), which of the above substances would be at -20 °C. a) NH3 b) SbH c) both substances d) none of the above 3. Place the order of the heat of fusion from lowest to highest for the following compounds? a) SrF2 → CaF2 → KFNaF b) CaF, SFNaF → KF c) KF → NaF → SF. CaF2 d) NaF → KF → Cafz → SrF2 e) None of the above 4. Assuming ideal behavior, which of the following aqueous solutions would be expected to exhibit the sales freezing point lowering (that is, which solution has the highest freezing point)? a) 0.1 m CaCl2 (strong electrolyte) b) 0.25 m CHOs (non-electrolyte) c) 0.05 m Al(SO.)» (strong electrolyte) d) 0.1 m KCl (strong electrolyte) e) Same for all 5. Which of the following liquids has the LOWEST vapor pressure at 25 °C? a) CH,CH,CH2CH2CH3 b) CH2CH2CH2CH2CH2CH3 c) CH3CH2CH2CH2CH2OH d) CH3CH,CH2CH2CH2CH,OH e) None of the above 6. What intermolecular force or bond is primarily responsible for the solubility of bain CHCl, liquid? a) dipole/dipole force b) hydrogen bonding force c) Induced dipole/induced dipole force d) dipole/induced dipole force e) None of the above 7. Which of the following compounds is NOT miscible (not mixing well) with water? a) CH3NH2 b) CS2 c) CH-COOH d) CH3CN e) HOCH,CH,OH 8. Place the following cations in order from the lowest to the highest hydration enthalpy in magnitude (fru attractive to most attractive to water): S, cl, and Br. a) Br → → S b) S4 → Br →CH c) S → C → Br dl cl → Br →S

Answer 1

Solution:

1) Option B

Solublity = KH x P

KH = henry constant

P = pressure

Solubility increases with pressure. The value of Henry constant is high for polar CH3Cl gas.

2) Option A

Boiling point of NH3 is lower than -20°C. Hence, it is liquid.

3) Option D

Heat of fusion depends upon the melting point. Since melting point of SrF2 is higher, hence its heat of fusion is highest.

4) Option D

Depression in freezing point = - i kf x m

Where, i = Vant Hoff factor

m = molality

Hence, lowering in freezing point is minimum for KCl.

Because, i value = 2

ΔTf = - 2 x kf x 0.1 = - 0.2 kf

5) Option D

Vapor pressure decreases on increasing the boiling point. Alcohol is polar hence it has highest boiling point, hence less vapor pressure.