How can adding heat to a reaction change the rate of a chemical reaction?
Well, it should speed up the reaction obviously...
An increase in heat energy means an increase in temperature, which also increases the average kinetic energy of the molecules in the process. This means that there are more collisions and higher frequency of successful collisions between the reactants during the reaction, therefore speeding up the chemical reaction.
A cool lab to see this effect is to do a basic acid-metal reaction between hydrochloric acid and zinc metal. A gas syringe, some test tubes, a stopwatch, and a stopper will be needed. Make sure to use the same size pieces of zinc metal and same concentration of acid.
Heat up one portion of the acid and put some zinc metal in it. Then record the amount of gas collected in a certain period of time, say five minutes. Repeat the experiment but with cold acid, with the same amount of time. Which one collected more gas?