J.R. S. answered 08/12/22
Ph.D. University Professor with 10+ years Tutoring Experience
Set up an ICE table ...
NH4Cl(g) ==> NH3(g) + HCl(g)
0.5...................0..............0..........Initial
-x..................+x..............+x.........Change
0.5-x...............x...............x..........Equilibrium
The expression for Kc is
Kc = [NH3][HCl] / [NH4Cl]
From the ICE table, we can obtain these values
1.1x10-2 = (x)(x) / (0.5-x)
Solve for x and that will give you the [NH3] at equilibrium.