Solid copper oxide reacts with ammonia gas according to the following equation: 3CuO + 2NH3 -> 3Cu + N2 + 3H20

Question

50 grams of CuO is placed in an 80L reaction vessel, and the vessel was evacuated. Ammonia gas was then gradually introduced into the vessel, slow enough for the reaction to proceed, until the total pressure in the vessel (after the reaction) was 1 atm. What are the partial pressures of all three gases in the vessel? (Temperature is 180 degrees celsius).

I was thinking of getting each of the moles, and then using PV-nRT for each one. Is that correct? Or is there a shorter way to do it? I was also thinking instead of using the ratio nA/ntotal= PA/Ptotal but I'm not sure how to go about it.

Thanks!

Answer 1

I would do this.
Use PV = nRT. You know P, V, R, and T. Solve for n = total mols.
Then use stoichiometry to calculate mols CuO that reacts and from that you get mols H2 and mols N2. Since you know
mols H2, mols N2, and total mols, you can subtract and find mols NH3.
Then use PV = nRT for each n of each gas and solve for p which will be the partial pressure of the gas.