Question

The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant.

H₂ (g) + Br₂ (g) ⇌ 2 HBr (g) Kc= 3.8 × 10⁴
4 HBr (g) ⇌ 2 H₂ (g) + 2 Br₂ (g) Kc= ?
a) 1.9 × 10⁴
b)5.1 × 10⁻³
c) 6.9 × 10⁻¹⁰
d) 1.6 × 10³

Answer 1

The value of a missing equilibrium constant can be obtained by multiplying the equilibrium constants of individual reactions involved in a sequence to find the equilibrium constant for the overall reaction.

Step-by-step explanation:

The student is requesting the determination of the value of a missing equilibrium constant for a chemical reaction. When dealing with multiple reactions that are part of a sequence or that combine to form a new reaction, the equilibrium constant for the overall reaction can be found by multiplying the equilibrium constants of the individual reactions. This principle is similar to how one would calculate the overall change in enthalpy (ΔH) for a reaction using Hess's Law, where ΔH is the sum of enthalpy changes for individual steps.

The student has provided an example where K3 is the product of K1 and K2, giving an equilibrium constant of 1.3 × 10-15 for the combined reaction. This concept can be applied to other sets of reactions to calculate missing equilibrium constants. Equilibrium calculations are essential when examining chemical reactions that reach a state of balance between the reactants and products, as represented by their respective concentrations in solution.