Q1. * Estimation of iron in an iron tablet

Question 1

What exactly is being measured in this experiment?

Answer 1

The amount of iron (II) sulfate (FeSO4) in an iron tablet

Question 2

What does FeSO4 stand for?

Answer 2

Iron (II) sulfate

Question 3

What is the chemical formula for iron (II) sulfate?

Answer 3

FeSO4

Question 4

What chemicals are needed for this experiment?

3

Answer 4

Potassium permanganate solution (0.01 M approximately)

Sulfuric acid solution (1 M)

Deionised water

Question 5

What is the first step in the procedure?

2

Answer 5

Accurately find the mass of five iron tablets using a clock glass and electronic balance

If in capsule form - empty the contents from five capsules onto a clock glass and find the mass

Question 6

What should be used to find the mass of the iron tablets?

2

Answer 6

A clock glass

An electronic balance

Question 7

How many iron tablets are needed for this experiment?

Answer 7

Five tablets are needed

Question 8

What must be done if the iron tablets are in capsule form before measuring?

Answer 8

Empty the contents of five capsules onto a clock glass then measure using an electronic balance

Question 9

What is the second step in the procedure, the mass of five iron tablets has just been found?
(2)

Answer 9

Grind up the tablets using a pestle and mortar

Add about 5 cm cubed of 1M sulfuric acid to the mortar to make the grinding process easier

Question 10

What is used to grind up the iron tablets?

Answer 10

A pestle and mortar

Question 11

What can be added to the mortar to make the grinding process easier?

Answer 11

Approximately 5cm cubed of 1M sulfuric acid

Question 12

What is the third step in the procedure, the iron tablets have just been ground up with5cm cubed of 1M sulfuric acid?
(2)

Answer 12

Transfer the paste of acid and tablets to a beaker containing about 100 cm cubed of 1M sulfuric acid

Make sure to rinse the mortar and pestle to ensure all traces of the tablets have been transferred to the beaker

Question 13

What is the paste of acid and tablets transferred to?

Answer 13

A beaker containing about 100cm cubed of 1M sulfuric acid

Question 14

What molar sulfuric acid is used during this experiment?

Answer 14

1M

Question 15

When transferring the paste, what must you make sure to remember to do?

Answer 15

Make sure to rinse the mortar and pestle

Question 16

When transferring the paste, why do you need to make sure to rinse the mortar and pestle?

Answer 16

To ensure all traces of the tablets have been transferred to the beaker

Question 17

What is the fourth step in the procedure, the paste has been transferred to a beaker of 100cm cubed sulfuric acid?
(2)

Answer 17

Stir to dissolve the paste

The outer coating may not dissolve which may give the solution a cloudy appearance

Question 18

When stirring the sulfuric acid containing the paste, what may occur?

Answer 18

The solution may become cloudy

Question 19

Why may the solution of sulfuric acid and the iron tablet paste become cloudy?

Answer 19

As some iron tablets have an outer coating which may not dissolve thus creating a cloudy appearance

Question 20

Why do some iron tablets have an outer coating?

Answer 20

To reduce the rate at which they dissolve in the stomach which reduces the chance of stomach upset

Question 21

What is the fifth step in the procedure, the solution of sulfuric acid and paste has been stirred and the solution has turned cloudy?
(3)

Answer 21

Transfer the solution to a clean 250 cm cubed volumetric flask

Transfer all the washings to the volumetric flask and make up to the mark with deionised water

Invert the stoppered flask about 20 times

Question 22

What should the 100m sulfuric acid solution and dissolved paste be transferred to?

Answer 22

A clean 250cm cubed volumetric flask

Question 23

What should you remember to do when transferring the dissolved paste and sulfuric acid solution?

Answer 23

Remember to transfer all the washings from the beaker to the volumetric flask

Question 24

What should you use to make the sulfuric acid solution and dissolved paste up to the mark on the volumetric flask?

Answer 24

Use deionised water to make the solution up to the 250cm cubed mark on the volumetric flask

Question 25

How many times should the flask be inverted?

Answer 25

Approximately 20 times

Question 26

What is the sixth step in the procedure, the volumetric flask has just been inverted 20 times.

Answer 26

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

Question 27

What pieces of equipment need to be washed with deionised water? (3)

Answer 27

A pipette A burette A conical flask

Question 28

What does the pipette, burette and conical flask need to be washed out with?

Answer 28

Deionised water

Question 29

What is the seventh step in the procedure, the equipment for the titration has just been washed with deionised water? (6)

Answer 29

The burette needs to be washed out with some of the potassium permanganate solution Then fill the burette using a funnel with the potassium permanganate solution until it is above the zero mark Remove the funnel from the burette Adjust the level of the solution in the burette to the zero mark Read from the top of the meniscus Ensure that the tap and space below the tap are also filled with the solution

Question 30

What does the burette need to be washed out with?

Answer 30

Some potassium permanganate solution

Question 31

What should be used when filling the burette with the potassium permanganate solution?

Answer 31

A funnel

Question 32

How should the burette be filled? | 5

Answer 32

Using a funnel add potassium permanganate solution until it is above the zero mark Remove the funnel Adjust the level of the solution to the zero mark Read from the top of the meniscus Ensure that the tap and space below it are filled with the solution

Question 33

How should the meniscus of the potassium permanganate solution in the burette be read?

Answer 33

Read from the top of the meniscus

Question 34

What is step 8 in the procedure, the burette has just been filled with potassium permanganate? (3)

Answer 34

Pour approximately 100 cm cubed of the iron tablet and sulfuric acid solution into a clean dry beaker Wash out the pipette with a small amount of this solution Pipette 25 cm cubed of the solution into the conical flask

Question 35

How much of the solution (sulfuric acid and iron tablet paste) in the volumetric flask should be poured into a beaker?

Answer 35

Approximately 100 cm cubed

Question 36

What should the pipette be washed out with?

Answer 36

The sulfuric acid and iron tablet paste solution

Question 37

How much of the iron tablet and sulfuric acid solution needs to be pipetted into a conical flask?

Answer 37

Approximately 25 cm cubed

Question 38

Where is the sulfuric acid and iron tablet solution pipetted to?

Answer 38

A conical flask - which will be used during the titration

Question 39

What is step 9 in the procedure, the conical flask has been filled with 25cm cubed of sulfuric acid and iron tablet solution?

Answer 39

Using a graduated cylinder add approximately 20 cm cubed of dilute sulfuric acid to the conical flask

Question 40

How much dilute sulfuric acid needs to be added to the graduated cylinder?

Answer 40

Approximately 20 cm cubed

Question 41

What needs to be added to the conical flask of sulfuric acid and iron paste solution?

Answer 41

Approx. 20 cm cubed dilute sulfuric acid

Question 42

What is step 10 in the procedure, dilute sulfuric acid has just been added to the conical flask? (3)

Answer 42

Carry out the titration until a faint permanent pink colour is observed at the end point Perform one rough and two accurate titrations The two accurate titrations should agree to within 0.1 cm cubed

Question 43

How do you know the end point has been reached?

Answer 43

A faint permanent pink colour is observed

Question 44

How many titrations should be carried out?

Answer 44

One rough and two accurate titrations

Question 45

Within how much should the two accurate titrations agree with each other?

Answer 45

Within 0.1 cm cubed

Question 46

What is step 11, in the procedure, the three titrations have been carried out?

Answer 46

Ensure that all glassware is washed out when the titrations have been finished as potassium permanganate stains glassware

Question 47

What is the chemical formula for potassium permanganate?

Answer 47

KMnO4

Question 48

What is KMnO4?

Answer 48

Potassium permanganate

Question 49

Why does glassware need to be washed when the titrations are over?

Answer 49

As potassium permanganate stains glassware

Question 50

What is the final step in the experiment?

Answer 50

Use the results of the experiment to calculate the mass of iron (II) sulfate in each tablet