Just having trouble understanding how to approach an ICE table question with no Kc and a volume change
Given
If you had 4.4 mol of a solid, A, placed in a 1L container which decomposed in to B and C (gas), B would slowly increase until 1.20M
reaction: $\ce{A(s) <=> B(g) + C(g)}$
Question
If the volume doubled and equilibrium was re-established, how many mol of A would there be?
My attempt:
Kc = 1.2M + 1.2M (not including solids)
Kc = 2.4M
for new ice table
2.4 = ((1.2 + x)(1.2 + x)) / 2 (because now litres is doubled)
0 = x^2 + 2.4x - 3.36
x = 0.9908 (which is wrong apparently)