Q1. * Estimation of iron in an iron tablet Flashcards
What exactly is being measured in this experiment?
The amount of iron (II) sulfate (FeSO4) in an iron tablet
What does FeSO4 stand for?
Iron (II) sulfate
What is the chemical formula for iron (II) sulfate?
FeSO4
What chemicals are needed for this experiment?
3
Potassium permanganate solution (0.01 M approximately)
Sulfuric acid solution (1 M)
Deionised water
What is the first step in the procedure?
2
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
What should be used to find the mass of the iron tablets?
2
A clock glass
An electronic balance
How many iron tablets are needed for this experiment?
Five tablets are needed
What must be done if the iron tablets are in capsule form before measuring?
Empty the contents of five capsules onto a clock glass then measure using an electronic balance
What is the second step in the procedure, the mass of five iron tablets has just been found?
(2)
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
What is used to grind up the iron tablets?
A pestle and mortar
What can be added to the mortar to make the grinding process easier?
Approximately 5cm cubed of 1M sulfuric acid
What is the third step in the procedure, the iron tablets have just been ground up with5cm cubed of 1M sulfuric acid?
(2)
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
What is the paste of acid and tablets transferred to?
A beaker containing about 100cm cubed of 1M sulfuric acid
What molar sulfuric acid is used during this experiment?
1M
When transferring the paste, what must you make sure to remember to do?
Make sure to rinse the mortar and pestle
When transferring the paste, why do you need to make sure to rinse the mortar and pestle?
To ensure all traces of the tablets have been transferred to the beaker
What is the fourth step in the procedure, the paste has been transferred to a beaker of 100cm cubed sulfuric acid?
(2)
Stir to dissolve the paste
The outer coating may not dissolve which may give the solution a cloudy appearance
When stirring the sulfuric acid containing the paste, what may occur?
The solution may become cloudy
Why may the solution of sulfuric acid and the iron tablet paste become cloudy?
As some iron tablets have an outer coating which may not dissolve thus creating a cloudy appearance
Why do some iron tablets have an outer coating?
To reduce the rate at which they dissolve in the stomach which reduces the chance of stomach upset
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)
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
What should the 100m sulfuric acid solution and dissolved paste be transferred to?
A clean 250cm cubed volumetric flask
What should you remember to do when transferring the dissolved paste and sulfuric acid solution?
Remember to transfer all the washings from the beaker to the volumetric flask
What should you use to make the sulfuric acid solution and dissolved paste up to the mark on the volumetric flask?
Use deionised water to make the solution up to the 250cm cubed mark on the volumetric flask
How many times should the flask be inverted?
Approximately 20 times
What is the sixth step in the procedure, the volumetric flask has just been inverted 20 times.
Wash out a pipette, burette and conical flask with deionised water
What pieces of equipment need to be washed with deionised water?
(3)
A pipette
A burette
A conical flask
What does the pipette, burette and conical flask need to be washed out with?
Deionised water
What is the seventh step in the procedure, the equipment for the titration has just been washed with deionised water?
(6)
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
What does the burette need to be washed out with?
Some potassium permanganate solution
What should be used when filling the burette with the potassium permanganate solution?
A funnel
How should the burette be filled?
5
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
How should the meniscus of the potassium permanganate solution in the burette be read?
Read from the top of the meniscus
What is step 8 in the procedure, the burette has just been filled with potassium permanganate?
(3)
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
How much of the solution (sulfuric acid and iron tablet paste) in the volumetric flask should be poured into a beaker?
Approximately 100 cm cubed
What should the pipette be washed out with?
The sulfuric acid and iron tablet paste solution
How much of the iron tablet and sulfuric acid solution needs to be pipetted into a conical flask?
Approximately 25 cm cubed
Where is the sulfuric acid and iron tablet solution pipetted to?
A conical flask - which will be used during the titration
What is step 9 in the procedure, the conical flask has been filled with 25cm cubed of sulfuric acid and iron tablet solution?
Using a graduated cylinder add approximately 20 cm cubed of dilute sulfuric acid to the conical flask
How much dilute sulfuric acid needs to be added to the graduated cylinder?
Approximately 20 cm cubed
What needs to be added to the conical flask of sulfuric acid and iron paste solution?
Approx. 20 cm cubed dilute sulfuric acid
What is step 10 in the procedure, dilute sulfuric acid has just been added to the conical flask?
(3)
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
How do you know the end point has been reached?
A faint permanent pink colour is observed
How many titrations should be carried out?
One rough and two accurate titrations
Within how much should the two accurate titrations agree with each other?
Within 0.1 cm cubed
What is step 11, in the procedure, the three titrations have been carried out?
Ensure that all glassware is washed out when the titrations have been finished as potassium permanganate stains glassware
What is the chemical formula for potassium permanganate?
KMnO4
What is KMnO4?
Potassium permanganate
Why does glassware need to be washed when the titrations are over?
As potassium permanganate stains glassware
What is the final step in the experiment?
Use the results of the experiment to calculate the mass of iron (II) sulfate in each tablet