# Homework Help: Gas state question

1. Jul 25, 2011

### AlchemistK

1. The problem statement, all variables and given/known data

Two temperature jacketed 1L bulbs are connected by stopcocks. Bulb A has a mix of H2O (g), CO2 (g) and N2 (g) at 25°C and at a pressure of 564 mm Hg. The second bulb is empty and at a temperature of -70°C. Once the stopcocks are opened what would be the composition in the two bulbs? ( CO2 sublimes at -78°C and N2 boils at -196°C)

2. Relevant equations

3. The attempt at a solution

As soon, as the stopcocks are opened and then later the apparatus is allowed to achieve equilibrium(given pressure will be 219 mm Hg), a part of the gasses in the first bulb would transfer into the second and since the temperature of the second bulb is -70°C, H2O would freeze into a solid. So bulb A would contain N2(g) and CO2(g) while bulb B would contain N2 (g), CO2(g) and H2O(s).

But the book has the answer as :A contains CO2 (g),N2(g) and H2O(s) and B contains CO2(g) and N2 (g).
Why is that true? Also, how can we calculate the number of H2O moles in the system?