Question

A system undergoes a two-step process. In the first step, the internal energy of the system increases by 218 J when 170 J of work is done on the system. In the second step, the internal energy of the system increases by 107 J when 172 J of work is done on the system.
1. For the overall process, find the heat?
2. What type of process is the overall process? Explain.

Answer 1

Answer:

1) Q total = Q1 +Q2 = 48 J + (-65J) = (-17J)

2) since the total heat exchanged is negative, the overall process is a cooling process

Explanation:

According to the first law of thermodynamics

ΔE = Q - W

where ΔE= change in internal energy , Q = heat and W= work done by the system to the surroundings

in the first step

Q1 = ΔE + W = 218 J  + (-170 J) = 48 J

in the second step

Q2 = ΔE + W = 107 J  + (- 172 J) = -65 J

the total heat is

Q total = Q1 +Q2 = 48 J + (-65J) = (-17J)

since the total heat exchanged is negative, the overall process is a cooling process .