Question

For the following change: H$_2$O(l) $\rightarrow$ H$_2$O(g)
5$^\circ$C $\rightarrow$ 100$^\circ$C
Select the correct answer

• A. q = +ve, w = +ve, $\Delta$U = +ve
• B. q = -ve, w = -ve, $\Delta$U = +ve
• C. q = +ve, w = -ve, $\Delta$U = +ve
• D. q = -ve, w = -ve, $\Delta$U = -ve

Hint:

For phase changes such as evaporation, heat is added to the system (q = +ve), and the system does work on the surroundings (w = -ve). The internal energy increases as a result.

Answer 1

The Correct Option is C