Question

By doing which of the following will you decrease the number of collisions and energy of reactant molecules?

increasing the pressure of the reactant mixture
decreasing the concentration of reactants
adding a catalyst
decreasing the temperature of the reactant mixture

Answer 1

Rates of Reaction

There are certain factors we can manipulate to change the rate of a reaction:

• Temperature is a measure of average kinetic energy. An increase in temperature leads to a faster rate.
• Concentration. The more reactant molecules available to react, the greater the rate.
• Pressure. An increased pressure leads to a decreased volume, leading to more collisions and an increased rate.
• Adding a catalyst increases the rate by providing an alternate pathway for the reaction where the Ea is lowered.

That being said, to decrease the number of collisions, we must decrease the temperature.