Question

Trial (Y), (2), [Y] [2] [Y] [2]2 1 0 | 8.15 0.377 .0 0.510 0.20 2 3 .697 0.25 0.0 0.259 0.510 0.136 0.178 0.25 0.129 1.46 2.04 1.05 1.04 8.15 0.143

The column y/Z*2 represents the equilibrium expression for this reaction. Explain why this is true

Answer 1

The equilibrium expression of a reaction (more commonly known as the equilibrium constant), is the value of the reaction quotients of the reaction at chemical equilibrium. For a given reaction, the equilibrium expression is independent of the initial concentrations and depends on the equilibrium concentrations of the species.

For example, consider a reaction
A + 2B $\rightleftharpoons$ 3C
The equilibrium expression for this reaction is given as:-

073 k= B) [4]

where [C],[B]&[A] are concentrations at equilibrium.

The value of equilibrium expression is constant and can be influenced only by reaction parameters like temperature, solvent, and Ionic strength. Since no such conditions have been mentioned in the question. We can assume that there are no external factors and the value of equilibrium expression should be constant for every combination of equilibrium concentration mentioned. Only $\frac{[Y]}{[Z]^2}$ matches this condition with all the combinations of equilibrium concentrations and hence it is the one representing equilibrium expression.