[ritwik08]

A 0.331 gram sample of pure ammonium carbonate (NH₄)₂CO₃.H₂O was placed in a evacuated 30 cm³ tube. it was heated at 250 C until it copmpletely decomposed.
Was there any liquid water in the tube?

All I know is this much:
1) The reaction:  
(NH₄)₂CO₃.H₂O 2NH₃+ CO₂+ 2H₂O
2) The liquid vapourises when the vapour pressure becomes equal to or greater than the outside pressure.


I also have one confusion. Why is that the vapor pressur due to water does not change when a water saturated gas is transeferred from say a 100 mL flask to a 50 mL flask, temperature remaining constant?

Please help me with these 2 queries.

[Borek]

I also have one confusion. Why is that the vapor pressur due to water does not change when a water saturated gas is transeferred from say a 100 mL flask to a 50 mL flask, temperature remaining constant?

Pressure increases twice, but vapor was already saturated - so it is oversaturated. System does the only thing it can to get back to the equilibrium - it condenses water out of the gas phase.