A vessel containing 10 kg of water is left out where it evaporates. If the temperature remains constant at 20C, what is the change in entropy (in kcal/K)? (The latent heat of vaporization at 20C is 585 cal/g.)
a. 30
b. 10
c. 20
d. 40
e. 290
[Ques. 2] Ten kilograms of water at 0C is mixed with 10 kg of water at 100C. The change in entropy (in cal/K) of the system is
a. 1 000
b. 480
c. 720
d. 240
e. 168
[Ques. 3] Find the change in entropy (in J/K) when 5.00 moles of an ideal monatomic gas are allowed to expand isobarically from an initial volume of 20 cm3 to a final volume of 100 cm3.
a. 167
b. 100
c. 67
d. 52
e. 152
[Ques. 4] An ideal gas is allowed to expand adiabatically. Assume the process is reversible. The change in entropy is
a. 0
b. nR ln (V2/V1)
c. nR ln (T2/T1)
d. kn ln (V2/V1)
e. kn ln (T2/T1)
[Ques. 5] Find the change in entropy (in J/K) when 5.00 moles of an ideal gas undergo a free expansion from an initial volume of 20 cm3 to a final volume of 100 cm3.
a. 71
b. 52
c. 67
d. 191
e. 208
[Ques. 6] An ideal gas is allowed to undergo a free expansion. If its initial volume is V1 and its final volume is V2, the change in entropy is
a. nR ln (V2/V1)
b. nRT ln (V2/V1)
c. nk ln (V2/V1)
d. 0
e. nR V2/V1
[Ques. 7] Determine the change in entropy (in J/K) when 5.00 moles of an ideal gas at 0C are compressed isothermally from an initial volume of 100 cm3 to a final volume of 20 cm3.
a. 191
b. 52
c. 71
d. 67
e. 208
[Ques. 8] Since Lice = 333 J/g, the change in entropy (in cal/K) when 1.00 kg of ice melts is
a. 144
b. 291
c. 312
d. 516
e. 80
[Ques. 9] The change in entropy of a mass m of a solid substance which has a latent heat of fusion L and melts at a temperature T is
a. LT/m
b. mL ln(T)
c. mLT
d. mL/T
e. L/mT
[Ques. 10] The change in entropy of 1.00 kg of water that is heated from 50C to 100C is (in cal/K)
a. 516
b. 312
c. 144
d. 946
e. 391
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