Consider the reaction:
A sample of pure NH4HS is placed in a sealed 2.0-L container and heated to 550 K at which the equilibrium constant is 3.5 × 10‒3. Once the reaction reaches equilibrium, what mass of NH3 is in the container? (Assume that the sample of NH4HS was large enough that equilibrium could be achieved.)
Solution 104P:
Step 1:
The equilibrium constant is
Keq = = [NH3][H2S]
Thus, we know that, NH4HS(s) is a solid, so that it is not included into the equilibrium constant.
Keq= 3.5 × 10‒3.
[NH3][H2S] = 3.5 × 10‒3.
From equation, 1 mol NH4HS(s) produces 1.0 mol of NH3(g) and (H2S each.
Thus,
[NH3] = [H2S]
Therefore.
Keq = [NH3][H2S] = [NH3]2
[NH3]2 = 3.5 × 10‒3.
[NH3] =
= 0.059 M
Step 2:
The moles of NH3 is = 2.0 L x 0.059 mol/ 1.0 L
= 0.118 mol
