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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
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What is a Chemical Reaction? • A process occurs when molecules interact to produce new chemical compounds • Examples: CH4 + 2O2 CO2 + 2H2O 2HCl + CaCO3 CaCl2 + CO2 + H2O
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