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Give an example of how an enzyme is used in industrial processes.

Enzymes (yeast) - fermentation

Give an everyday use of an enzyme.

Biological washing powders, dishwasher tablets

What is an enzyme?

A biological catalyst.

They catalyse reactions which take place in the living cells of plants and animals.

Why do cars with catalytic converters use lead free petrol.

To prevent the lead poisoning the catalyst.

Why are cars fitted with catalytic converters ?

The convert harmful gases into less harmful

gases.

Name two toxic gases produced in a car engine. What does a catalytic

converter change them to?

Carbon monoxide is converted to carbon dioxide.

Oxides of nitrogen are converted to nitrogen.

What can reduce the surface activity of a catalyst?

Poisoning

What name is given to a catalyst which is in the same state

as the reactants?

Homogeneous

What is meant by a heterogeneous catalyst?

The catalyst is in a different state than the reactants

What is a catalyst?

A substance which -

speeds up a chemical reaction

is not used up by the reactions

How can the course of a reaction be followed?

By measuring changes in -

-concentration

-mass

-volume of reactants and products.

How is the average rate of a reaction calculated?

change in quantity

change in time

In a reaction , 60cm3 of gas were collected in 20 s.

Calculate the average rate of the reaction, in cm3 s-1, in the first 20 s.

Change in quantity = 60

change in time = 20

60/20 = 3.

How is the rate of a reaction calculated?

Rate = 1/time 1/t

Time = 1/rate

Use the graph to find the time taken, in seconds, when the experiment was carried out using

0.1 mol-1 sodium hydroxide solution.

From the graph the rate = 0.02

Time is 1/rate 1/0.02 = 50

What factors can affect the rate of a reaction?

Concentration Temperature Particle size Use of a catalyst

How can changes in concentration, temperature, particle size and use of

a catalyst affect the rate of a reaction?

Increase concentration - increase rate Increase temperature - increase rate ( except when using an enzyme ) Decrease particle size - increase rate Use of catalyst - increase rate

Explain how concentration affects the rate of the reaction in

terms of the collision theory.

Concentration increases - more particles to collide - more successful collisions - increased rate of reaction

Explain how particle size affects the rate of the reaction in terms

of the collision theory.

Particles become smaller - surface area increases - more successful collisions - increased rate of reaction

Building Blocks 1b Int 2

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