Chemical Reactions and Equations

Chemical Reactions Chemical bonds are broken and reformed creating new substances Cellular respiration: glucose and O2 reacting to form energy, CO2 and H2O C6H12O6 + O2 -------> CO2 + H2O + energy An iron chain rusting Fe + O2 ----> Fe2O3 Reactants -----> Products

Balanced Equations Law of Conservation of Mass : matter cannot be created or destroyed, it just changes forms Number of atoms of each element on reactant side must equal the number of atoms on product side Coefficients: Numbers in front of formula; represent number of molecules of substance

C6H12O6 + 6O2 ----> 6CO2 + 6H2O + energy Balanced Equations 4 Fe + 3 O2 ----> 2 Fe2O3 C6H12O6 + 6O2 ----> 6CO2 + 6H2O + energy Coefficients in red

Balanced Equations Try This: CH4 + O2 -----> CO2 + H2O

Balance this: H2O2 -----> H2O + O2 2H2O2 -----> 2H2O + O2

Energy of Reactions Activation Energy: amount of energy necessary to start a chemical reaction In every chemical reaction there is a change in energy due to the breaking and making of bonds.

Exothermic Reaction

Exothermic Reaction Releases energy- usually in the form of heat Reactants have more energy than products (products more stable) Reaction more likely to go forward

Exothermic Reaction Activation Energy Amount of Energy released Products Reactants

Endothermic Reaction

Endothermic Reaction Absorbs energy Reactants have less energy than products (reactants more stable) Reaction less likely to go forward

Enzymes Reactions in living organism occur too slowly Need to speed up On the energy diagram what will enzymes affect? Activation Energy

Energy Diagram with Enzyme