If 0.45kg is changed by a reversible process to steam at 100°c, determine the entropy of: 1. the water 2. the surrounding. 3. the universe (water+surroundings) as a whole.

1) 2726.5 J/K      2) decrease                     3) 0

Explanation:

1)

change in entropy is given by

here Q=mL where L is the latent heat of vaporization. therefore

2)

since the heat is taken from surroundings, the change in entropy is negative therefore entropy of surrounding will decrease.

3) since there is no heat exchange with universe  therefore , Q=0 in this case

d) physical means can be used to separate the components of air.