Question

$H_{2}O\left(s\right)\to H_{2}O\left(l\right)$
This phase transition is carried out at constant temp and pressure then work done during the process:

• A. $W<0$
• B. $W>0$
• C. $W=0$
• D. can be determined

Answer 1

The correct option is B $W>0$

Work done= $-P_{ext}(V_{final}-V_{initial})$

when $H_2{O}_{\left(s\right)}\to {H_{2}O}_{\left(l\right)}$

$V_f<V_i$ (frozen water has more volume than the liquid water)

$\Rightarrow \Delta V=V_f-V_i=negative$

$\therefore W=-P\times (-V)=PV$

$\Rightarrow W>0$ .