Chem II help?

When ΔG° = -5.45 × 10³ J/mol:

ΔG° = -R T ln(K)
-5.45 * 10³ = - 8.314 * (273 + 25) * ln(K)
K = e^{(5.45 * 10³) / (8.314 * 298)} = 9.02

______________ A(aq) ___ + ___ B(aq) ___ ⇌ ___ C(aq) _____ K = 9.02
Initial: ________ 0.3 M _______ 0.40 M _______ 0 M
Change: _______ -x M ________ -x M _________ +x M
Equilibrium: _ (0.30 - x) M ___ (0.40 - x) M _____ x M

At equilibrium:
K = [C] / {[A] [B]}
9.02 = x / {(0.30 - x) (0.40 - x)}
9.02 (0.30 - x) (0.40 - x) = x
9.02x² - 6.314x + 1.0824 = x
9.02x² - 7.314x + 1.0824 = 0
x = {7.314 ± √(7.314 - 4 * 9.02 * 1.0824)} / {2 * 9.02}
x = 0.20 or x = 0.62 (rejected)

At equilibrium:
[A] = (0.30 - x) M = (0.30 - 0.20) M = 0.10 M
[B] = (0.40 - x) M = (0.40 - 0.20) M = 0.20 M
[C] = x M = 0.20 M


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When ΔG° = -3.78 × 10³ J/mol:

ΔG° = -R T ln(K)
-3.78 * 10³ = - 8.314 * (273 + 25) * ln(K)
K = e^{(3.78 * 10³) / (8.314 * 298)} = 4.60

______________ A(aq) ___ + ___ B(aq) ___ ⇌ ___ C(aq) _____ K = 4.60
Initial: ________ 0.3 M _______ 0.40 M _______ 0 M
Change: _______ -y M ________ -y M _________ +y M
Equilibrium: _ (0.30 - y) M ___ (0.40 - y) M _____ y M

At equilibrium:
K = [C] / {[A] [B]}
4.60 = y / {(0.30 - y) (0.40 - y)}
4.60 (0.30 - y) (0.40 - y) = y
4.60y² - 3.22y + 0.552 = y
4.60y² - 4.22y + 0.552 = 0
y = {4.22 ± √(4.22 - 4 * 4.60 * 0.552)} / {2 * 4.60}
y = 0.16 or y = 0.76 (rejected)

At equilibrium:
[A] = (0.30 - y) M = (0.30 - 0.16) M = 0.14 M
[B] = (0.40 - y) M = (0.40 - 0.16) M = 0.24 M
[C] = y M = 0.16 M