CCC Class 5- Spontaneity, Entropy, and Free Energy

For which process is ΔS negative?

• evaporation of 1 mol of CCl4(l)

• mixing 5 mL ethanol with 25 mL water

• compressing 1 mol Ne at constant temperature from 1.5 L to 0.5 L

• raising the temperature of 100 g Cu from 275 K to 295 K

• grinding a large crystal of KCl to powder

Ten identical coins are shaken vigorously in a cup and then poured out onto a table top. Which of the following distributions has the highest probability of occurrence?

• T10H0

• T8H2

• T7H3

• T5H5

• T4H6

A two-bulbed flask contains 7 particles. What is the probability of finding all 7 particles on the left side?

• 3.50%

• 2.65%

• 0.78%

• 0.14%

• 1.56%

Which of the following result(s) in an increase in the entropy of the system?

• I

• II, V

• I, III, IV

• I, II, III, IV

• I, II, III, V

The second law of thermodynamics states that:

• The entropy of a perfect crystal is zero at 0 K.

• The total energy of the universe is constant.

• The energy of the universe is increasing.

• The entropy of the universe is increasing.

• The energy of the universe is constant.

Which of the following statements is true?

• The total energy and entropy of the universe are both increasing.

• The total energy of the universe is increasing, but the entropy is constant.

• The total energy of the universe increases, while the entropy decreases.

• The total energy of the universe is constant, but the entropy is increasing.

• None of these.

A 100-mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5°C to 20.8°C as the solid dissolves. For the dissolving of the solid

• ΔH < 0

• ΔSuniv > 0

• ΔSsys < 0

• ΔSsurr > 0

• none of these

A chemical reaction is most likely to be spontaneous if it is accompanied by

• increasing energy and increasing entropy

• lowering energy and increasing entropy

• increasing energy and decreasing entropy

• lowering energy and decreasing entropy

• none of these (A-D)

Assume that the enthalpy of fusion of ice is 6020 J/mol and does not vary appreciably over the temperature range 270-290 K. If one mole of ice at 0°C is melted by heat supplied from surroundings at 279 K, what is the entropy change in the surroundings, in J/K?

• 22.1

• 21.6

• 0.0

• –21.6

• –22.1

If the change in entropy of the surroundings for a process at 439 K and constant pressure is –326 J/K, what is the heat flow absorbed by for the system?

• 326 kJ

• 1.35 kJ

• –143 kJ

• 113 kJ

• 143 kJ