Question

1kg of water at 273K is brought in contact with a heat reservoir at 373K
1-What is the change in entropy of water when temp reaches 373K
2-what is change in entropy of
the reservoir
the universe

Answer 1

Question#18383

Molecular physics

1kg of water at 273K is brought in contact with a heat reservoir at 373K

1-What is the change in entropy of water when temp reaches 373K

2-what is change in entropy of

the reservoir

the universe

Answer:

Let:

$$T _ {1} = 2 7 3 K$$ $$T _ {2} = 3 7 3 K$$ $$m = 1 k g$$

$\Delta E - ?$

Such as $\Delta E = \frac{\Delta Q}{T}$ , were: $\Delta E$ - changing of entropy, $\Delta Q$ - changing of heat, $T$ - temperature.

For water:

$$\Delta E = \frac {c m (T _ {2} - T _ {1})}{T _ {2}}$$

Were c - heat capacity of water = 4.1813 KJ/kg*K

$$\Delta E = \frac {4 . 1 8 1 3 * 1 * (3 7 3 - 2 7 3)}{3 7 3} = 1. 1 2 K J$$

The entropy of water is increase on 1.12 KJ

According to the law of conservation energy:

The entropy of reservoir is decrease on 1.12 KJ,

And the entropy of universe is not change.