C6 Rates of Reaction Recap

C6 Rates of Reaction Recap Lesson

Keywords:

Collision : one object hitting another.

Rate : speed

Activation Energy : energy needed for the reaction to take place.

Reactants : what you add together.

Products : what you make.

Gradient : 'steepness' of a straight line.

Open Ended

Think!

How do you know a chemical reaction has happened?

Hint: Think about the picture of the fireworks, how do you know from that picture a reaction is happening (what do you SEE).

Collision Theory

When you add two or more substances (reactants) together, a reaction can occur.

A reaction will only happen if the substances touch or Collide with enough ENERGY (the activation energy).

There are lots of factors that can affect how well particles collide.

Remember particles are moving all the time but liquids move more freely than solids, and gases move the most freely.

Multiple Choice

Why does increasing temperature increase rate of reaction?

• Particles gain more energy (and so move around more)

• Particles change size

• Particles are less likely to collide with each other

Multiple Choice

Concentrated juice tastes very strong. We dilute juice with water. This ........................... the concentration of the juice.

• Increases

• decreases

• does not affect

Multiple Choice

A scientist wants two gases to react. This is difficult as gases move around a lot. The scientists puts the gases in a sealed syringe and pushes the plunger. What happens to the pressure of the gases?

• Increases

• Decreases

• Stays the same

Open Ended

A student reacts a piece of magnesium ribbon with hydrochloric acid. How could they increase the rate of this reaction?

Open Ended

What is a catalyst?

Calculating Rate

How fast a reaction goes is referred to as its rate.

Rate is calculated by seeing how much product is made over time.

Example: Rate = volume of gas collected ÷  time (in seconds) 

OR

Rate is calculated by seeing how much reactant is used up over time.

Example: Rate = mass of reactant ÷ time (in seconds) 

Multiple Choice

The graph on the previous slide shows volume of gas collected over time.

What piece of equipment would be best for collecting a gaseous product?

Multiple Choice

When the rate of reaction is zero (a flat line), what has happened to the reaction?

• The reaction has slowed down

• The reaction has become more violent

• The reaction has ended.

• The reaction has sped up.

Multiple Choice

How do you calculate the gradient of a straight line?

• y ÷ x

• change in x ÷ change in y

• y + x

• Change in y ÷ change in x

Multiple Choice

Which one of the follow could be the units for rate?

• Kg

• cm³

• g/s

• min