This document discusses factors that affect the rate of chemical reactions such as activation energy, temperature, concentration, surface area, and catalysts. It explains that reactions require a minimum amount of energy called activation energy to occur. Temperature increases the rate of most reactions because faster moving molecules collide more frequently and with greater force. Higher concentration and greater surface area increase reaction rate by providing more opportunities for collisions between reactants. Catalysts speed up reactions by lowering the activation energy or increasing the reaction surface area.