As more heat is given to the molecules of the reactants, they gain kinetic energy, and move more quickly, and violently. Acid rain causes the erosion or weathering of limestone. The reaction between limestone and acid rain is exothermic - it gives out heat.
Limestone is a calcium carbonate, and it is alkali.
A reaction occurs when the molecules of two or more reactants collide into one another. Then the reaction takes place. After the collision and subsequent reaction has taken place, 'products' are produced. In the case of this experiment carbon dioxide is the product of the reaction between limestone and acid rain - basically hydrochloric acid and water. I predict that if the temperature goes up by 20 C then the rate of reaction will go up by 4 times.