S4 - Rate of reaction experiments

Question 1

What does the reaction of hydrochloric acid and marble chips represent?

Answer 1

The effect of breaking the solid up into small bits

Question 2

Describe an experiment using hydrochloric acid and marble chips

Answer 2

• Measure the volume of gas evolved with a gas syringe and take readings at regular intervals - Make a table and plot the results on a graph - Repeat the experiment with exactly the same volume of acid but with the marble crunched up - Then repeat with the same mass of powdered marble instead of marble chips - Compare results

Question 3

On the graph for hydrochloric acid and marble chips, what should x and y be?

Answer 3

The independent variable (x) = time The dependent variable (y) = volume

Question 4

What does the following graph conclude?

Answer 4

An increase in surface area (small chips) causes more frequent collisions, so the rate of the reaction is faster.

Question 5

What does the reaction of magnesium metal with dilute HCL represent?

Answer 5

The effect of increases concontration (as is the marbe/acid reaction)

Question 6

What does the reaction with magnesium metal and dilute HCL give off?

Answer 6

A hydrogen gas which can be measured with a mass balance.

Question 7

What are the independent and dependent varibles in the magnesium metal with dilute HCL?

Answer 7

• Independant variable = Time
• Dependant variable = Mass loss

Question 8

What else can be used instead of a mass balance?

Answer 8

A gas syringe

Question 9

What is the method for the magnesium metal and dilute HCL?

Answer 9

• Take readings at regular intervals
• Put the results in a table and work out the loss of mass for each reading
• Plot a graph
• Repeat with more concentrated acid solutions but the same amount of magnesium and volume of acid

Question 10

What would you expect the rates of reaction graph to look like?

Answer 10