The rate of the reaction is affected by the following factors:
1. Concentration (higher concentration of reactant particles increases the rate of reaction since it leads to more collisions)
2. Surface area ( higher surface area, such as grinding something into powder, increases the rate of the reaction)
3. Temperature (higher temperature increases the rate of the reaction).
4. Catalyst (catalyst increases the rate of the reaction by lowering the activation energy). Catalysts can be reused over and over again.
When the reaction releases energy, delta H is negative, and the reaction is said to be exothermic. Energy will be shown on the right side, together with the products. When the reaction absorbs energy, delta H is positive, and the reaction is said to be endothermic. Energy will be shown on the reactant side.
Reference table I shows what reactions are endothermic and which ones are exothermic, by showing whether deltaH is positive or negative.
Students taking Chemistry Regents exam should also know that many reactions can go forward as well as in reverse. These reactions eventually establish equilibrium. At equilibrium, the rate for the forward reactions is equal to the rate of the reverse reaction. While the rates are equal, the concentrations of reactants and products are not equal. However, they stay constant and do not change.
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