Past edta Mock Questions

Question 1

Name the homologous series that edta is a member of

Answer 1

Carboxyl acids

Question 2

Name the indicator used in this titration

Answer 2

Eriochrome black T/ Solochrome black

Question 3

State the colour change observed at the end of the titration

Answer 3

wine red to blue

Question 4

A small quantity of a solution is added before the titration proceeds, what is this solution?

Answer 4

Buffer solution

Question 5

A small quantity of a buffer solution is added before the titration proceeds, what is the purpose of this solution?

Answer 5

To maintain a pH of 10 during the reaction

Question 6

During the titration, some of the solution got splashed high up the sides of the conical flask.
What should you do to rectify this situation?
(2)

Answer 6

Swirl the conical flask to mix the contents

Wash the sides down with deionised water

Question 7

Why does washing the sides of the conical flask during the titration with deionised water not affect the result of the experiment?

Answer 7

Deionised water does not contain ions which means it will not affect the concentration of reactants in the flask

Question 8

Describe the correct procedure for rinsing the pipette and transferring the solution to the conical flask
(7)

Answer 8

Rinse with deionised water

Then rinse with water sample

Fill pipette using a pipette filler to above the mark/graduation line

Adjust to have bottom of meniscus on mark

Read at eye level

Drain under gravity into titration flask

Touch pipette against side of flask

Question 9

If the water sample had been boiled would the titre value be bigger, smaller or the same?
Explain

Answer 9

The titre would have been smaller as boiling removes temporary hardness