4.3.2 Effect of Concentration and Pressure

Question 1

How can you increase concentration?

Answer 1

Dissolve more solute particles.

Question 2

How can you increase pressure?

Answer 2

Making the reaction vessel smaller.

Question 3

What is an investigation that demonstrates how concentration affects rate?

Answer 3

The effect of concentration on rate can be demonstrated by reacting sodium thiosulphate solution with hydrochloric acid. In this reaction, a solid (sulphur) is slowly produced. After a while, you can’t see through the mixture any longer. This is measured by observing a black cross under the mixture. Rate is calculated by rate = 1/time taken for cross to disappear.

Question 4

Is rate proportional to concentration?

Answer 4

Rate is proportional to concentration, we know this because it is a straight line through the origin.