Answer:
Kc = 26.67
Explanation:
Step 1: Data given
Number of moles of A = 1.0 mol
Number of moles of B = 1.0 mol
Number of moles of D = 0.50 moles
Volume = 5.0 L
Step 2: The balanced equation
A(g) + 3B(g) ⇋ C(g) + 2D(g)
Step 3: Number of initial moles
Moles A = 1.0 mol
Moles B = 1.0 mol
Moles C = 0 moles
Moles D = 0 moles
[A] = 1.0 mol / 5.0 L = 0.2 M
[B] = 1.0 mol / 5.0 L = 0.2 M
[C] = 0 M
[D] = 0 M
Step 4: Moles at the equilibrium
For 1 mol A we have 3 moles B to produce 1 mol C and 2 moles D
There will react X of A, this give (1.0 - X) moles
There will reacto 3X for B this gives (1.0 - 3X) moles
There will be X produced for C this gives X moles
There will be 2X produced for D this gives 2X moles
After equilibrium has been established, 0.50 mole of D
2X = 0.50 moles or X = 0.25 moles this gives 0.25 moles / 5.0 L = 0.05 M
Step 5: Calculate Kc
The concentration at the equilibrium
[A] = 0.2 - 0.05 = 0.15M
[B] = 0.2 - 0.15 = 0.05M
[C] = 0.05M
[D] = 0.1M
Kc = (0.05)(0.1)² / (0.15)(0.05)³
Kc = 26.67