Reasoning Problem 16.18 A container holds 2.4 kg of water that is initially at 3

Question

Reasoning Problem 16.18
A container holds 2.4 kg of water that is initially at 328 K and is converted to steam at 392 K.

Assuming the volume of the system does not change, what is the change in the internal energy of the system?

Part 1 of 3 - Recognize the Principles

Which of the following statements are true for this problem? (Select all that apply.)

1. If the volume doesn't change, no work is done.

2. The change in internal energy is equal to the heat transferred to the system.

3. The change in internal energy is equal to the heat minus the work on the system.

4. A finite amount of work is done.

Explanation / Answer

first law of thermo dynamics is
dQ =dU+dW ........ (1)
if v =constant ,then dv =0
so ,eq'(1) becomes dQ =dU ...... (2)
there fore internal energy is
dU =mC_v dT ....... (3)
for water C_v =4186 J/kg.deg C
internal energy du =2.4*4186*(392-328)
dU =642.969*10^3 J
..................................................................
A)
if volume dies not change ,V =constant ,then dV =0
so ,work done W =PdV =0
option (1) IS TRUE.
B)
from equation (2),we have
dQ =dU
so , option (2) is true.
C)
from eq(1),we have
dQ =dU+dW
if work done is zero ,then we get dQ =dU
so ,this (3) is wrong.
D)
according to problem ,we have dV =0 ,work done W =0 J
SO ,option (4) is wrong

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