Briefly explain each true/false and multiple choice answer . a.) Assuming they h

Question

Briefly explain each true/false and multiple choice answer.

a.) Assuming they have the same initial temperature, a reversible isothermal expansion of one mole of monoatomic ideal gas from 2.00 L to 11.00 L will have a larger entropy change in the system than a reversible adiabatic expansion of the same gas from 2.00 L to 11.00 L.

b.) For a reversible heat pump, q cycle > 0

c.) The internal energy of an isolated system will remain constant even if a chemical reaction occurs.

d.) It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system and the performance of an equivalent amount of work by the system on the surroundings.

e.)  If 2.0 kJ heat is added to each of two blocks of solid iron under constant pressure conditions, and block A is initially at 40.0 oC, and block B is initially at 80.0 oC, which iron block will experience the smaller entropy increase? a. block A b. block B c. both blocks will experience the same entropy increase d. cannot be determined from the information given

f.)  Which of the following has a standard enthalpy of formation equal to zero? a. solid Hg b. Br2 vapor c. solid I2 d. O3 (ozone) e. none of these answers

Explanation / Answer

a) A reversible isothermal expansion of one mole of monoatomic ideal gas from 2.00 L to 11.00 L will have a larger entropy change in the system than a reversible adiabatic expansion of the same gas from 2.00 L to 11.00 L.

True

Entropy change for an reversible adiabatic change is 0.

For isothermal it is dS = nRln(V2/V1)

b) For a reversible heat pump, q cycle > 0

False

first law of thermodunamics, dU = q+w

For a closed reversible cycle q = w = 0

c) The internal energy of an isolated system will remain constant even if a chemical reaction occurs.

True

According to the first law of thermodynamics which is also known as the law of conservation of energy, internal energy can be transformed from one form to another but overall system will have a constant internal energy at all times.

d) It is impossible for a system to undergo a cyclic process whose sole effects are the flow of heat into the system and the performance of an equivalent amount of work by the system on the surroundings.

True

In a cyclic system or a machine which can convert entire energy into work.

e) If 2.0 kJ heat is added to each of two blocks of solid iron under constant pressure conditions, and block A is initially at 40.0 oC, and block B is initially at 80.0 oC, which iron block will experience the smaller entropy increase?

b. block B

Entropy is heat supplied/T, so for blick B with hogher intial temperature will have smaller entropy increase.

f) Which of the following has a standard enthalpy of formation equal to zero?

c. solid I2

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