Page 1310 - Chemistry--atom first
P. 1310
1300 Answer Key
63. 100.26 °C
65.(a) (b) Vapor pressures are: CH3OH: 55 torr; C2H5OH: 18 torr; (c) CH3OH: 0.75; C2H5OH: 0.25
67. The ions and compounds present in the water in the beef lower the freezing point of the beef below −1 °C.
69.
The observed change equals the theoretical change; therefore, no dissociation occurs.
71.
Colloidal System
Dispersed Phase
Dispersion Medium
starch dispersion
starch
water
smoke
solid particles
air
fog
water
air
pearl
water
calcium carbonate (CaCO3)
whipped cream
air
cream
floating soap
air
soap
jelly
fruit juice
pectin gel
milk
butterfat
water
ruby
chromium(III) oxide (Cr2O3)
aluminum oxide (Al2O3)
73. Colloidal dispersions consist of particles that are much bigger than the solutes of typical solutions. Colloidal particles are either very large molecules or aggregates of smaller species that usually are big enough to scatter light. Colloids are homogeneous on a macroscopic (visual) scale, while solutions are homogeneous on a microscopic (molecular) scale.
75. If they are placed in an electrolytic cell, dispersed particles will move toward the electrode that carries a charge opposite to their own charge. At this electrode, the charged particles will be neutralized and will coagulate as a precipitate.
Chapter 12
1. A reaction has a natural tendency to occur and takes place without the continual input of energy from an external
source.
3. (a) spontaneous; (b) nonspontaneous; (c) spontaneous; (d) nonspontaneous; (e) spontaneous; (f) spontaneous
5. Although the oxidation of plastics is spontaneous, the rate of oxidation is very slow. Plastics are therefore kinetically stable and do not decompose appreciably even over relatively long periods of time.
7. There are four initial microstates and four final microstates.
9. The probability for all the particles to be on one side is This probability is noticeably lower than the result
for the four-particle system. The conclusion we can make is that the probability for all the particles to stay in only one part of the system will decrease rapidly as the number of particles increases, and, for instance, the probability for all molecules of gas to gather in only one side of a room at room temperature and pressure is negligible since the number of gas molecules in the room is very large.
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