Chemical Reactions and Enzymes. What is a Chemical Reaction? A process occurs when molecules...

Chemical Reactions and Enzymes

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

http://www.chem4kids.com/files/bio_enzymes.html

http://www.chem4kids.com/files/bio_enzymes.html

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