3.02 Neutralisation reactions

Question 1

What is a neutralisation reaction?

Answer 1

A reaction whare an acid reacts with a base to produce salt and water

Question 2

Write the general word equation for a neutralisation reaction

Answer 2

acid + base –> salt + water

Question 3

Write the ionic equation for a neutralisation reaction

Answer 3

H+ (aq) + OH- (aq) –> H2O (l)

Question 4

What pH is the solution following a neutralisation reaction?

Answer 4

7

Question 5

WHat is the relationship between the concentration of H+ and OH- ions in a neutral solution?

Answer 5

They are equal (but not necessarily zero)

Question 6

What colour does univeral indicator turn at the end of a neutralisation reaction?

Answer 6

7

Question 7

Is calcium oxide and acid or a base?

Answer 7

Base

Question 8

Write the equation for the reaction of hydrocholoric acid with calcium oxide

Answer 8

2HCl + CaO —-> CaCl2 + H2O

Question 9

You are asked to do an experiment to see how the pH of hydrochloric acid changes with gradual addition of calcium oxide. Describe how you would do this.

Answer 9

1. Measure out a volumne of dilute HCl (using measuring cylinder) and pour into conical flask
2. Measure out ome calcium oxide (using a mass balance)
3. Add a little calcium oxide and stir with a glass rod
4. Measure the pH using a pH probe or universal indicator, and note it down
5. Repeat steps 2 to 4 until all the acid has reacted (i.e. some unreacted CaO remains unreacted at the bottom of the flask)
6. Plot a line graph: mass of base added on x axis, pH on y axis

Question 10

You are asked to do an experiment to see how the pH of hydrochloric acid changes with gradual addition of calcium oxide.

Sketch a graph showing how you would expect the pH of the solution to change with the amount of base added.

Answer 10

See graph p121 GCP

Important parts of the sketch: gradual increase in pH with addition of base; sudden change in pH as you approach the point where the pH is neutral; flat line at pH 7