Question

1.

2CH4(g)⇌C2H2(g)+3H2(g)

K = 0.160 at 1658 ∘C . What is Kp for the reaction at this temperature?

Express your answer numerically.

2.

N2(g)+3H2(g)⇌2NH3(g)

Kp = 4.75×10⁻³ at 306 ∘C . What is K for the reaction at this temperature?

Enter your answer numerically.

3.

Given the two reactions

H2S⇌HS− + H+,   K1 = 9.12×10⁻⁸, and

HS−⇌S2− + H+,   K2 = 1.52×10⁻¹⁹,

what is the equilibrium constant Kfinal for the following reaction?

S2− + 2H+⇌H2S

Enter your answer numerically.

4.

Given the two reactions

PbCl2⇌Pb2+ + 2Cl−,   K3 = 1.89×10⁻¹⁰, and

AgCl⇌Ag+ + Cl−,   K4 = 1.15×10⁻⁴,

what is the equilibrium constant Kfinal for the following reaction?

PbCl2 + 2Ag+⇌2AgCl + Pb2+

Express your answer numerically.

Answer 1

Question 1.

According to the ideal gas equation: PV = nRT

i.e. P = (n/V)RT

i.e. P = cRT, where 'c' is the concentration of the gas

Therefore, Kp = Kc * (RT)ⁿ

Where Kp is the equilibrium constant in terms of partial pressures

Kc is the equilibrium constant in terms of concentrations

R is the universal gas constant = 0.08206 L atm mol^-1 K^-1

n = no. of moles of gaseous products - no. of moles of gaseous reactants

For the given reaction, n = (1 + 3) - 2 = 2

T = 1658 ^oC = (1658+273.15) K = 1931.15 K

And Kc = 0.16

Now, Kp = 0.16 * (0.08206 * 1931.15)² = 4.018*10³