Answer to poll

Congratulations! 73% of the poll participants chose the correct answer. Now, we will have a re-cap of the question and the explanation of the answer and choices.

The question:

Which of the following factors does NOT affect the rate of reaction.

Answer:

Increasing concentration of the products.

Increasing concentration of products does not affect most reaction. Except for biological reactions. In biological reactions where enzymes are required, the product molecule will cause the deactivation of the enzyme and hence slowing the reaction.

The other options:

1) Catalyst.

A catalyst does affect the rate of reaction. A catalyst helps to speed up the reaction by lowering the activation energy (activation energy can be seen from the energy profile diagram) of the reaction. This would result in more molecules in having that minimium energy for reaction to occur.

2) Decreasing temperature.

Temperature does affect the reaction rate. When we increase the temperature, the reaction becomes faster because the molecules gain more kinetic energy because of the temperature. Hence, more molecules will have that minimum energy for reaction to occur (as denoted by the Maxwell-Boltzman distribution curve). So, what happens when we decrease temperature? The opposite happens; the molecules moves slower, the molecules has less kinetic energy and hence less molecules have the minimum energy for reaction to occur.

Other factors that affect rate:

1) Concentration of reactants.

However, do take this factor with care. When a reaction is zero order with respect to a reactant, changing the concentration of that reaction will have no effect on the rate of reaction.