Factors That Affect theFactors That Affect theRate of a ReactionRate of a Reaction

““So…A little heatSo…A little heat

and some of my new,and some of my new,

super-effective super-effective catalyst catalyst

and the Pumpkinator and the Pumpkinator 7000 is…Oh my 7000 is…Oh my

God…”God…”

What is a Chemical What is a Chemical Reaction?Reaction?

A chemical reaction occurs when the particles A chemical reaction occurs when the particles of the reactants collide with one another and of the reactants collide with one another and stick together in new combinations to create stick together in new combinations to create new substances – these are the products.new substances – these are the products.

When the particles of the reactants strike one When the particles of the reactants strike one another and form a new substance, we can another and form a new substance, we can look at this as a look at this as a ““meaningful collisionmeaningful collision”” – it – it gave us some product.gave us some product.

We can manipulate/control several factors We can manipulate/control several factors related to chemical reactions that will help us related to chemical reactions that will help us speed them up and get more product at a speed them up and get more product at a quicker pace.quicker pace.

Before we examine these factors, we must Before we examine these factors, we must look at the particles themselves and see how look at the particles themselves and see how they behave and interact.they behave and interact.

The Fast & the FuriousThe Fast & the Furious The nature of particles is addressed in what The nature of particles is addressed in what

is known as the is known as the Particle TheoryParticle Theory or, as it is or, as it is also known, the also known, the Kinetic Molecular TheoryKinetic Molecular Theory (KMT)(KMT)..

This theory has several simple points that This theory has several simple points that discuss what matter really is and how the discuss what matter really is and how the particles that make up matter really behave.particles that make up matter really behave.

1.1. All matter is made of tiny particles that are All matter is made of tiny particles that are constantly moving.constantly moving.

2.2. The particles’ speed depends on the amount of The particles’ speed depends on the amount of energy they possess. The greater the energy; the energy they possess. The greater the energy; the greater the speed.greater the speed.

3.3. The particles will move in a straight line until it The particles will move in a straight line until it strikes another particle. It will then bounce off of strikes another particle. It will then bounce off of this particle and continue to move in a straight this particle and continue to move in a straight line, but in a new direction.line, but in a new direction.

Particles & StateParticles & State This illustration shows how the This illustration shows how the

particles act in each of the three particles act in each of the three states of matter.states of matter.

SOLIDSOLID LIQUIDLIQUID GASGAS

A Real Smash Hit!A Real Smash Hit! When we see how the particles of a substance actually When we see how the particles of a substance actually

behave, we can then start to control this behaviour and behave, we can then start to control this behaviour and get a chemical reaction to occur much quicker.get a chemical reaction to occur much quicker.

To get a reaction to proceed at a quicker pace, we must To get a reaction to proceed at a quicker pace, we must get the particles involved to get into more of those get the particles involved to get into more of those “meaningful collisions”“meaningful collisions” – we are talking about the – we are talking about the high-impact type!high-impact type!

The four factors that we can use to affect the rate of a The four factors that we can use to affect the rate of a chemical reaction are:chemical reaction are:

1.1. TemperatureTemperature2.2. ConcentrationConcentration3.3. Surface AreaSurface Area4.4. CatalystsCatalysts

These factors will help us by doing one of two things:These factors will help us by doing one of two things: speed up the particlesspeed up the particles and make the collisions more and make the collisions more

violent (and meaningful at the same time)violent (and meaningful at the same time) increase the number of collisionsincrease the number of collisions overall and this overall and this

should give us more meaningful type as well.should give us more meaningful type as well.

Turning Up the Heat!Turning Up the Heat! The term The term ““temperaturetemperature”” is used to indicate is used to indicate

the amount of heat energy an object has.the amount of heat energy an object has. As you add more heat to an object, the As you add more heat to an object, the

particles of the reactants absorb this heat and particles of the reactants absorb this heat and start moving faster and faster. This makes the start moving faster and faster. This makes the collisions between the particles much more collisions between the particles much more violent and meaningful – the formation of violent and meaningful – the formation of product will increase quickly.product will increase quickly.

So…As temperature increase; reaction rate So…As temperature increase; reaction rate increases.increases.

ExamplesExamples:: Using a Bunsen burner to heat a test tube in a lab.Using a Bunsen burner to heat a test tube in a lab. Baking a cake in an oven.Baking a cake in an oven.

““Made From Made From Concentrate”Concentrate” ConcentrationConcentration is the number of particles in is the number of particles in

a given volume of space.a given volume of space. As you increase the concentration of As you increase the concentration of

substance, you are increasing the number of substance, you are increasing the number of particles in the reaction. This means that you particles in the reaction. This means that you will have a higher number of collisions and a will have a higher number of collisions and a greater chance that some of those collisions greater chance that some of those collisions will be the “meaningful” type.will be the “meaningful” type.

So…As concentration increases; the reaction So…As concentration increases; the reaction rate increases as well.rate increases as well.

ExamplesExamples:: Using a more concentrated acid to etch some Using a more concentrated acid to etch some

glass.glass. Adding more octane to gasoline to burn more Adding more octane to gasoline to burn more

efficiently.efficiently.

Chemicals Exposing Chemicals Exposing Themselves?!?!Themselves?!?!

Surface areaSurface area is the amount of a substance that is is the amount of a substance that is exposed to the outer environment.exposed to the outer environment.

When substances are going to react with one When substances are going to react with one another, they have to collide and this means that another, they have to collide and this means that the surface of one substance must fit the surface of the surface of one substance must fit the surface of the other substance.the other substance.

The more surface area a substance has exposed; The more surface area a substance has exposed; the more particles are exposed to and are able to the more particles are exposed to and are able to react with other particles. You are now able to have react with other particles. You are now able to have more collisions taking place – more collisions more collisions taking place – more collisions means more chances of “meaningful collisions” means more chances of “meaningful collisions” taking place.taking place.

So…As more surface area is exposed on a So…As more surface area is exposed on a substance; the faster the rate of reactionsubstance; the faster the rate of reaction

ExamplesExamples:: Grinding up a metal block into powder for a reaction.Grinding up a metal block into powder for a reaction. Using wood chips and kindling to start a fire.Using wood chips and kindling to start a fire.

CatalystsCatalysts A A catalystcatalyst is a substance that increases the rate of a is a substance that increases the rate of a

reaction by lowering the activation energy required by reaction by lowering the activation energy required by the reaction.the reaction.

The The activation energyactivation energy is the amount of energy that a is the amount of energy that a reaction needs to get started. It’s like the spark reaction needs to get started. It’s like the spark needed to get a can a gasoline to explode.needed to get a can a gasoline to explode.

A catalyst helps turn the reactants into products A catalyst helps turn the reactants into products without becoming a product in the reaction – it is not without becoming a product in the reaction – it is not consumed in the reaction like a fuel.consumed in the reaction like a fuel.

There are biological catalysts called There are biological catalysts called enzymesenzymes that that allow the reactions in your body to proceed without allow the reactions in your body to proceed without consuming too much of your energy.consuming too much of your energy.

So…The rate of reaction is quicker when a catalyst is So…The rate of reaction is quicker when a catalyst is used.used.

ExamplesExamples:: Digestive enzymes in your body breaking down your food.Digestive enzymes in your body breaking down your food. A catalytic converter in a car breaking apart the contaminants A catalytic converter in a car breaking apart the contaminants

in exhaust.in exhaust.

THE ENDTHE END