Question

4. The internal energy of a gas decreases by 344]. If the process is adiabatic, how much energy is transferred as heat? How much work is done on or by the gas?

Answer 1

In an adiabatic process, there is no heat transfer to or from the gas (\(Q = 0\)). Therefore, the change in internal energy (\( \Delta U \)) is equal to the work done on or by the gas (\(W\)):

\[
\Delta U = Q + W
\]

Since \(Q = 0\) for an adiabatic process, we have:

\[
\Delta U = W
\]

Given that the internal energy of the gas decreases by 344 J (\( \Delta U = -344 \, \text{J} \)), we can substitute into the equation:

\[
-344 \, \text{J} = W
\]

This implies that:

\[
W = -344 \, \text{J}
\]

This negative value indicates that work is done **by** the gas on the surroundings.

To summarize:

- Energy transferred as heat (\(Q\)) = 0 J (since the process is adiabatic).
- Work done by the gas (\(W\)) = -344 J, meaning 344 J of work is done **by** the gas.

If we wanted to express work done **on** the gas, it would be +344 J.