Question

a) The change in the internal energy of a system that absorbs 2,500 J of heat and that does 7,655 J of work on the surroundings is _________ J.

b) The ΔE of a system that absorbs 12.4J of heat and does 4.2 J of work on the surroundings is __________ J.

Answer 1

Answers:

a) 10155 J

b) 16.6 J

Explanation:

According to the First Law of Thermodynamics we have:

$\Delta E=Q + W$

Where:

$\Delta E$ is the total change in the internal energy of a system

$Q$ is the heat exchanged between the system and its surroundings

$W$ is the work done on the system

a) In this case $Q=2500 J$ and $W=7655 J$, hence:

$\Delta E=2500 J + 7655 J=10155 J$

b) In this case $Q=12.4 J$ and $W=4.2 J$, hence:

$\Delta E=12.4 J + 4.2 J=16.6 J$