Question

A system undergoes a process consisting of the following two steps:

Step 1: The system absorbs 71 J of heat while 38 J of work is done on it.
Step 2: The system absorbs 38 J of heat while performing 71 J of work.
Calculate ΔE for the overall process.

Answer 1

The total change in internal energy (ΔE) for the overall two-step process is 76 J, which is calculated by adding the change in internal energy for each step: Step 1 being 109 J and Step 2 being -33 J.

Step-by-step explanation:

To calculate the change in internal energy (ΔE) for the overall process, we use the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system (AQ) minus the work done by the system (AW). The formula for this is ΔE = Q - W.

For Step 1, the system absorbs 71 J of heat and 38 J of work is done on it, so the change in internal energy (ΔE1) is ΔE1 = +71 J - (-38 J) = 71 J + 38 J = 109 J.

For Step 2, the system absorbs 38 J of heat and performs 71 J of work, so the change in internal energy (ΔE2) is ΔE2 = +38 J - 71 J = -33 J.

The total change in internal energy for the overall process is the sum of the changes in each step: ΔE = ΔE1 + ΔE2 = 109 J + (-33 J) = 76 J