Question

When a reaction is at chemical equilibrium, what is true about the forward and reverse reactions?

Answer 1

The condition of equilibrium specifies equality between forward and reverse rates.

Explanation:

`A+BrightleftharpoonsC+D`

There is a rate forward, `k_f[A][B]`, and a rate backward, `k_r[C][D]`.

At `"equilibrium"` these rates are equal, i.e.

`k_f[A][B]=k_r[C][D]`, on rearrangement,

`k_f/k_r=([C][D])/([A][B])`

The quotient, `k_f/k_r`, is better know as `K_"eq"`, the equilibrium constant. It must be experimentally measured.