Question

What is the entropy change of a 0.349 g spoonful of water that evaporates completely on a hot plate whose temperature is slightly above the boiling point of water?

Answer 1

Answer:

$\Delta S = 2.11 J/K$

Explanation:

As we know that entropy change for phase conversion is given as

$\Delta S = \frac{\Delta Q}{T}$

Here we know that heat required to change the phase of the water is given as

$\Delta Q = mL$

here we have

$m = 0.349 g = 3.49\times 10^{-4} kg$

L = 2250000 J/kg

now we have

$\Delta Q = (3.49 \times 10^{-4})\times 2250000$

$\Delta Q = 788.9 J$

also we know that temperature is approximately same as boiling temperature

so we have

$T = 373 k$

so here we have

$\Delta S = \frac{788.9}{373}$

$\Delta S = 2.11 J/K$