Unit 7 Reaction Energy SECTION 1 REACTION RATE

Unit 7: Reaction Energy SECTION 1: REACTION RATE

Energy in Reactions • In order for a reaction to occur, energy MUST be involved. • Reactions that release (give off) energy are called exothermic reactions • Reactions that absorb (take in) energy are called endothermic reactions • This energy absorbed or released is beyond the activation energy – energy required to cause a reaction to occur

Reaction Rate • The rate at which reactants change into products over time • Relates to how fast the reaction is occurring

Factors Affecting Reaction Rate • Temperature: – Generally, as you increase temperature, you increase the rate of the reaction – As you heat a substance, the molecules move around faster • They collide and react more!

Factors Affecting Reaction Rate • Surface Area: – The surface of a substance is the area that will react with its surroundings – An increase in the surface area results in an increase in the amount of exposure the substance has to the surroundings – Increased surface area increases reaction rate

Factors Affecting Reaction Rate • Concentration: – Refers to the number of particles of a substance in a given area – The more particles present, the higher the concentration and therefore, the quicker a reaction will occur

Factors Affecting Reaction Rate Temperature Surface Area Concentration Increase in Reaction Rate

Factors Affecting Reaction Rate • Catalysts: – Substance that affects the reaction rate without being used up in the process – Instead of affecting the particles that are reacting, a catalyst DECREASES the activation energy of a reaction; therefore, making the reaction occur more easily!