[dancinggurl13]

When 0.1 mol of HCl gas is placed in a 10 L container at 25 C, the pressure is about the same as observed when 0.1 mol of NH3 is placed in an identical box at the same temeperature. However, when 0.05 mol of HCl and 0.05 mol of NH3 are mixed in a 10 L container at 25 C, a noticeably lower pressure is observed. Explain this.

I think this has something to do with Raoult's law but I am not sure.

[Burner]

Hint:

When 0.1 mol of HCl gas is placed in a 10 ml container at 25 C, the pressure is about the same as observed when 0.1 mol of NH3 is placed in an identical box at the same temeperature. However, when 0.05 mol of HCl and 0.05 mol of NH3 are mixed in a 10 L container at 25 C, a noticeably lower pressure is observed. Explain this.

[Borek]

My guess is that the latter 10 L is just a typo.

Hint: can ammonia react with acids?

[Enthalpy]

They don't stay as two gases.