Question

which will increase the rate of a chemical reaction?
adding a catalyst
decreasing the pressure
decreasing the temperature
removing a catalyst

Explanation:

A catalyst lowers the activation energy of a chemical reaction. According to the Arrhenius equation \(k = A e^{-\frac{E_a}{RT}}\) (where \(k\) is the rate constant, \(A\) is the pre - exponential factor, \(E_a\) is the activation energy, \(R\) is the gas constant, and \(T\) is the temperature), a lower \(E_a\) results in a higher \(k\) (rate constant), thus increasing the reaction rate. Decreasing pressure (for gaseous reactions) reduces the frequency of collisions between reactant molecules, decreasing the rate. Decreasing temperature reduces the kinetic energy of molecules, so fewer molecules have energy equal to or greater than the activation energy, decreasing the rate. Removing a catalyst would increase the activation energy (back to its original value without the catalyst), decreasing the rate.

Answer:

Adding a catalyst.