Activation Energy Activation Energy and Equilibriumand Equilibrium

Unit 14Unit 14

Insight Schools Insight Schools

Physical SciencePhysical Science

Getting Chemical Reactions GoingGetting Chemical Reactions Going

EnergyEnergy is usually needed to break the bonds is usually needed to break the bonds and get the reaction going.and get the reaction going.

This can be a spark, This can be a spark,

flame, heat, or even a feather. flame, heat, or even a feather.

Getting Chemical Reactions GoingGetting Chemical Reactions Going

Activation energy Activation energy is the term for the energy is the term for the energy needed to break the bonds so new bonds needed to break the bonds so new bonds can formcan form

Activation Energy

Energy Released Net

Endothermic and Exothermic ReactionsEndothermic and Exothermic ReactionsExothermic Exothermic ReactionsReactions

Endothermic Endothermic ReactionsReactions

EnergyEnergy Energy is Released to Energy is Released to the surroundingsthe surroundings

Energy is Absorbed Energy is Absorbed from the surroundingsfrom the surroundings

SignsSigns Gets HotGets Hot

FlameFlame

LightLight

Gets ColdGets Cold

Dark colorDark color

ExamplesExamples Combustion of Combustion of MethaneMethane

Cold PackCold Pack

PhotosynthesisPhotosynthesis

Factors That Influence Reaction RatesFactors That Influence Reaction RatesAffect on Reaction RateAffect on Reaction Rate

CatalystCatalyst Increases the Reaction Rate

Concentration of ReactantsConcentration of Reactants Increase in Concentration increases the reaction rate because of an increase in

particle collisions.

Surface AreaSurface Area More surface area increases the reaction rate. (Smaller particles give a greater

overall surface area when all the particles surfaces are added together.)

TemperatureTemperature Increase in Temperature increases the reaction rate because of an increase in

particle collisions.

StirringStirring Increases the Reaction Rate by increasing the number of collisions.

Factors That Influence Reaction RatesFactors That Influence Reaction RatesAffect on Reaction RateAffect on Reaction Rate

CatalystCatalyst

Concentration of ReactantsConcentration of Reactants

Surface AreaSurface Area

TemperatureTemperature

StirringStirring

The Affect of CatalystsThe Affect of Catalysts

Exothermic vs EndothermicExothermic vs Endothermic

EquilibriumEquilibriumThe point in a chemical reaction where the

rate at which reactants and products are being produced is equal.

Equilibrium ConcentrationEquilibrium Concentration

Symbolized by [ ] around the compounds Symbolized by [ ] around the compounds or ionsor ions

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]H2O

Changes in the Equilibrium Changes in the Equilibrium ConcentrationConcentration

Symbolized by [ ] around the compounds Symbolized by [ ] around the compounds or ionsor ions

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]

H2O

H2O evaporating

H2O added

Changes in the Equilibrium ConcentrationChanges in the Equilibrium Concentration

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]

[NaCl] [NaCl] [Na[Na++] and [Cl] and [Cl--]]

H2O evaporating

H2O added

Le Chatelier’s Le Chatelier’s PrinciplePrinciple

Le Chatelier’s PrincipleLe Chatelier’s PrincipleIf something is done that disturbs a If something is done that disturbs a system at equilibrium, that system system at equilibrium, that system responds in a way to counteract what responds in a way to counteract what was done.was done.

TemperatureTemperatureIncrease temperature:Increase temperature:

favors the endothermic reaction.favors the endothermic reaction.

Decrease temperature:Decrease temperature:

favors the exothermic reaction.favors the exothermic reaction.

Pressure/Volume ChangesPressure/Volume ChangesIncrease pressure:Increase pressure: favors the reaction producing favors the reaction producing fewer moles of gas.fewer moles of gas.

Decrease pressure:Decrease pressure: favors the reaction producing favors the reaction producing more moles of gas.more moles of gas.

Examples of Changes in EquilibriumExamples of Changes in Equilibrium

CO2

CO2

CO2

CO2

Concentration ChangesConcentration Changes

Increase [reactant]:Increase [reactant]: favors favors the forward reactionthe forward reaction

Increase [product]:Increase [product]: favors favors the reverse reactionthe reverse reaction