Chemical Reactions and Enzymes

What is a Chemical Reaction? A process occurs when molecules interact to produce new chemical compounds Examples: CH 4 + 2O 2  CO 2 + 2H 2 O 2HCl + CaCO 3  CaCl 2 + CO 2 + H 2 O

Sign of Chemical Reactions Gas formed Precipitate (solid from solutions) formed Color change Temperature change Odor produced

Chemical Reactions and Energy Energy is required to break chemical bonds Energy is released when new bonds form Some reactions are spontaneous Many reactions require some energy input to get started

Catalysts Catalysts are substances that speed up a reaction without being used up in the reaction They act by reducing the energy needed to start the reaction

Factors Affecting Chemical Reactions Temperature Concentration of reactants Presence of catalyst Surface area exposed on solid reactants

Enzymes Enzymes are proteins that act as catalysts Many enzymes are involved the processes of photosynthesis, cellular respiration, and fermentation

Factors Affecting Enzymes pH Temperature Concentration of substrate Inhibitory molecules Activator molecules pH or temperature can denature or change the shape of the enzyme so it no longer fits the substrate