[NewtoAtoms]

A gas sample heated in a cylinder used 650 kJ of heat. A piston that compresses the gas does 800 kJ of work. What is the change in internal energy, ΔE, of the gas during this process


I have done some leg work and I am hoping to god I am correct:

ΔE = q + w
ΔE = (650kJ) + (800 kJ)
ΔE = 1450 kJ

a result of the gas being heated and compressed, the energy of the gas increases by 1450 kJ. Is this at all correct? Or should it be -650 kJ???

Thank you for your help.

[Yggdrasil]

Correct.  Since you are heating the gas (adding heat energy to the gas) and compressing the gas (doing work on the gas), both q and w are positive.

[NewtoAtoms]

Thank you so much for your help Yggdrasil.

Have a great day!