Question

Write the expressions for the equilibrium constants for the following reactions, making the approximation of replacing activities by molar concentrations or partial pressures:

a. Gly(aq) + Ala(aq) ⇌ Gly-Ala(aq) + H₂O(l)

b. Mg²⁺(aq) + ATP⁴⁻(aq) ⇌ MgATP²⁻(aq)

c. 2 CH₃COCOOH(aq) + 5 O₂(g) ⇌ 6 CO₂(g) + 4 H₂O(l)

Answer 1

Solution: Write the expression for the equilibrium constant for the following reactions:

a. Gly(aq) + Ala(aq) ⇌ Gly-Ala(aq) + H₂O(l)

Then, ₂K=[Gly−Ala][H₂O][Gly][Ala]

But ₂[H₂O]=1⇒K=[Gly−Ala][Gly][Ala]

b. Mg²⁺(aq) + ATP⁴⁻(aq) ⇌ MgATP²⁻(aq)

Then, ²⁻²⁺⁴⁻K=[MgATP²⁻][Mg²⁺][ATP⁴⁻]

c. 2 CH₃COCOOH(aq) + 5 O₂(g) ⇌ 6 CO₂(g) + 4 H₂O(l)

Then, ₂⁶₃²₂⁵K=[CO₂]⁶[CH₃COCOOH]²[O₂]⁵

But \([H₂O] = 1 \Rightarrow K = \frac{[CO₂]⁶}{[CH₃COCOOH]²[O₂]⁵}

Therefore, But \([H₂O] = 1 \Rightarrow K = \frac{[CO₂]⁶}{[CH₃COCOOH]²[O₂]⁵}