- #1

- 1,132

- 128

- Homework Statement
- For this part(b) of this problem:

When a gas expands along AB (see below), it does 20 J of work and absorbs 30 J of heat. When the gas expands along AC, it does 40 J of work and absorbs 70 J of heat. (a) How much heat does the gas exchange along BC? (b) When the gas makes the transition from C to A along CDA, 60 J of work are done on it from C to D. How much heat does it exchange along CDA?

The solution is ##90J##. However, I am getting ##30J##. My working is

##\Delta E_{int_{CDA}} = -\Delta E_{int_{CA}} = -30 ##

##-30 = Q - (-60) ##

## 30 J = Q ##

Can some please let me know what I am doing wrong?

Many thanks!

- Relevant Equations
- First Law of Thermodynamics ##\Delta E_{int} = Q - W##