This question is about the enthalpy change of reaction

Question

The work done to compress a gas is 74kJ. As a result, 26kJ of heat is given off to the surroundings. The energy of the gas: A) increases by 48 kJ B) increases by 100kJ C) decreases by 48 kJ D) decreases by 100kJ

Answer 1

ΔE = q - w

 

 

In this equation, q is the amount of heat added to the system and w is the amount of work done by the system.

In the problem, work is done on the system so w is negative, and heat is given off so q is also negative.

 

ΔE = -26kJ - -74kJ

ΔE = -26kJ + 74 kJ

ΔE = 48kJ

 

 

Because ΔE is positive, the energy of the gas increases.