Edta - steps in procedure

Question 1

What is the first step of the procedure?

Answer 1

Wash out a pipette, burette and conical flask with deionised water

Question 2

What is the second step of the procedure?

2

Answer 2

100cm3 of the edta solution is poured into a clean, dry beaker

200cm3 of the hard water sample is poured into another beaker

Question 3

What is the third step of the procedure?

Answer 3

Rinse out the pipette with some of the hard water sample and the burette with some of the edta solution

Question 4

What is the fourth step of the procedure?

Answer 4

Pipette 50cm3 of the hard water sample into a conical flask

Question 5

What is the fifth step of the procedure?

Answer 5

1cm3 of the buffer solution and a spatula tip of the solid Eriochrome Black T indicator is added to the conical flask

Question 6

What is the sixth step of the procedure?

Answer 6

Clamp the burette vertically on the retort stand

Question 7

What is the seventh step of the procedure?

5

Answer 7

Using a small funnel, fill the burette above the zero mark with the solution

Remove the funnel from the burette and adjust the bottom of the meniscus of the edta solution to the zero mark

Ensure that the tap and space below the tap are also filled

Open the tap briefly and allow the liquid to run out into a beaker marked ‘waste’

Check that there is no air bubbles in the nozzle

Question 8

What is the eight step of the procedure?

2

Answer 8

Place a white tile on the base of the retort stand and put the conical flask on the white tile

The colour of the solution in the conical flask should be wine red

Question 9

What is the ninth step of the procedure?

2

Answer 9

Titrate in the usual manner until the colour of the indicator changes from wine red to blue

Carry out one rough and two accurate titrations which should agree to within 0.1cm3

Question 10

What is the tenth step of the procedure?

Answer 10

Using the results of this experiment, calculate the hardness of the water