Question

What is the entropy change when 275 g of water is heated from 20.0°C to 80.0 °cz О 214 J/K O 1600 JK 196 J/K O 236 J/K What is the change in entropy when 175.0 g of steam condenses at the boiling point of water? A. O -943.3 JAK B. 0 -1058 J/KC. -252.8 JK D. 0 -3948 J/K

Answer 1

1- 214 J/K

2- -1058 J/K (roughly)

Step-by-step explanation:

1-Given:

mass of water
`m=275 g`

initial temperature
`t_1=20 C=293K`

final temperature
`t_2=80C=353K`

Specific heat capacity of water
`C=4.18(J)/(g* K)`

1-We can first calculate the change in entropy through the formula:

`dS=m* C* ln ((t_1)/(t_2) )`

`dS=275* 4.18* ln((353)/(293))\\ =214 J/K`

2-Given:

mass of water
`m=0.175 kg`

latent heat of vaporization
`L=2.26* 10^6J/kg`

(In the case of condensation, we use a negative sign because the heat is expelled out of the system not inside of it)

heat emitted from the condensation of steam:

`Q=mL\\\\=0.175 * -2.26* 10^6\\=-3.955* 10^5 J\\\\dS=Q/T\\\\\\=(-3.955* 10^5)/(373)\\ \\=-1060J/K=-1058 J/K (roughly)`