CHE 168 Answers for Problem Set #3

Workshop CHE 168
Answers for
Problem Set #3

1.

(a) 9.79 mol/kg
(b) 0.086 mol/kg
(c) 8.82 mol/kg

2.

(a) 43.01% by mass
(b) 0.139
(c) 7.70 mol/kg
(d) 5.827 mol/L

3. 23 mol/L

4.

(a) 0.0261 mol
(b) 0.00452 mol
(c) 0.0197 mol
(d) 0.750 mol

5. fp/bp:

(a) - 118.2 ^{^o}C/78.9 ^{^o}C
(b) - 1.4 ^{^o}C/100.4 ^{^o}C [0.385 m (0.770 m particles)]
(c) - 117.6 ^{^o}C /78.6 ^{^o}C; (d) - 1.9 ^{^o}C /100.5 ^{^o}C [1.00 m]

6. 102.5 ^{^o}C
7. 1.8 x 10^{^-}^² g/mol
8. 1.39 x 10^⁴ g/mol

* - * - * - *

Constants for #5:

Solvent	Normal fp, ^{^o}C	Kf, ^{^o}C /m	Normal bp, ^{^o}C	Kb, ^{^o}C /m
ethanol	- 117.6	1.99	78.4	1.22
water	0.0	1.86	100.0	0.52

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