Question

18g of liquid water is placed in a flexible bag, the air is excluded, and the bag is sealed. It is then placed in a microwave oven where the water is boiled to make steam at 100C. What is the volume of the bag after all the water has boiled? Assume that the pressure inside the bag is equal to atmospheric pressure.

so this is what i did so far:

18 g of water = 1 mol.
then i used the ideal-gas equation,
PV = nRT, to find the volume at 100°C (= 373 K).
P = 1 atm
n = 1 mol
R = 0.083 L·atm/mol·K;
T = 373 K, so
V = nRT/P = 31 L
right?

Answer 1

yes. There was an easier way to do this. One mole of "steam" at STP is 22.4L

new volume: 22.4 * 373/273=you guessed it.
This constant pressure is called Charles' Law.

Answer 2

i'll use that for future