Chemistry Heat & Work

Question

A chemical reaction is run in which 740 Joules of heat are generated and 175 Joules of work is done on the system.

Calculate the change in the internal energy of the chemical system.

 E = Joules

Answer 1

One form of the equation is ΔE = Q - W where Q is the heat absorbed and W the work done.

In this case heat is generated so Q is negative, and word is done on the system so W is also negative.

The equation becomes ΔE = -740 j - (-175 j) = -565 j. The internal energy decrease by 565 j