Entropy and the Second Law Video Lessons

Concept

# Problem: a. An object at 400 K absorbs 25.0 kJ of heat from the surroundings. What is the change in entropy ΔS of the object? Assume that the temperature of the object does not change appreciably in the process. Express your answer numerically in joules per kelvin.b. Two objects form a closed system. One object, which is at 400 K, absorbs 25.0 kJ of heat from the other object, which is at 500 K. What is the net change in entropy ΔSsys of the system? Assume that the temperatures of the objects do not change appreciably in the process. Express your answer numerically in joules per kelvin.

###### FREE Expert Solution

Change in Entropy:

$\overline{){\mathbf{∆}}{\mathbf{S}}{\mathbf{=}}\frac{\mathbf{∆}\mathbf{Q}}{\mathbf{T}}}$

The net change in entropy:

$\overline{){\mathbf{∆}}{{\mathbf{S}}}_{\mathbf{s}\mathbf{y}\mathbf{s}}{\mathbf{=}}{\mathbf{∆}}{{\mathbf{S}}}_{{\mathbf{1}}}{\mathbf{+}}{\mathbf{∆}}{{\mathbf{S}}}_{{\mathbf{2}}}}$

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###### Problem Details

a. An object at 400 K absorbs 25.0 kJ of heat from the surroundings. What is the change in entropy ΔS of the object? Assume that the temperature of the object does not change appreciably in the process. Express your answer numerically in joules per kelvin.

b. Two objects form a closed system. One object, which is at 400 K, absorbs 25.0 kJ of heat from the other object, which is at 500 K. What is the net change in entropy ΔSsys of the system? Assume that the temperatures of the objects do not change appreciably in the process. Express your answer numerically in joules per kelvin.