# Question #1e7c6

Apr 6, 2015

No, at equilibrium the number of reactant molecule does not equal the number of product molecules.

But the rate at which reactant molecules form products is equal to the rate at which product molecules return to reactants.

Consider this analogy.

The apples from a tree fall equally on each side of a fence.

A boy on one side and an old man on the other side throw the apples at each other.

The boy is fast and agile, but the man is old and slow. The boy can pick up and return the apples ten times as fast as the man can.

The apples will accumulate on the man's side.

Eventually there will be an equilibrium at which there are ten times as many apples on the man's side and the boy is returning the apples as fast as the man can throw them.

The number of "reactant" and "product" apples is not the same, but the rate at which the apples go back and forth across the fence is equal.

Here is a video which shows the dynamic equilibrium which occurs when an amount of salt is added to water which is more than what is needed to produce a saturated solution. Notice that the amount of salt in the dissolved state is not necessarily equal to the amount of salt in the solid state.

NaCl(s) $r i g h t \le f t h a r p \infty n s$ NaCl(aq)

video from: Noel Pauller