P1 – Task 1, M1 – Task 2, M2 – Task 3
Iodine Extraction
Equipment:
Goggles
Fume cupboard
2X 250cmᶾ beaker
Filter funnel
Filter paper
Separating funnel
Bunsen burner
Tripod
Gauze
Method:
1. Set up the equipment with the Bunsen burner and tripod on the heatproof mat with the gauze on top of the tripod.
2. Add the seaweed to the tin lid and place on top of the gauze (try not to use any ‘pods’ of seaweed as they pop when heated which could be dangerous). Light the Bunsen burner and heat the seaweed in the tin lid on the blue flame until it has all been reduced to ash.
This step involves heating the seaweed so it is reduced to ash to extract the iodine (in which it is present as an iodide) and make it easier to incorporate with …show more content…
Next add 2cmᶾ of dilute sulfuric acid to the remaining solution and then add 10cmᶾ of hydrogen peroxide solution. This should create a deep brown colour of iodine as the hydrogen peroxide and iodide ions oxidise.
This step allows the hydrogen peroxide and iodide ions to oxidise, creating iodine, which is needed in the next stage.
Ensure that the sulfuric acid does not come into contact with the skin. When the hydrogen peroxide is added to the solution it should turn brown, if it doesn’t the experiment will need to be restarted.
5. Transfer the mixture to a separating funnel and add 10cmᶾ of cyclohexane. Stopper the separating funnel and secure with your thumb. Ensure the tap is closed fully then shake the funnel for 30 seconds. Turn the funnel upside down and open the tap to release the pressure build up.
The iodine created in the previous stage is soluble in cyclohexane which means they can become one layer and any impurities can be separated and stay in the aqueous layer …show more content…
You must keep your thumb over the stopper when shaking the funnel as the stoppers can sometimes be loose and you don’t want to lose any of the liquid. It is very important that you open the tap and release the gas that builds up it the separating funnel and it will put pressure on the funnel and it could crack if not released.
6. Close the tap again and set up the funnel on a clamp stand. Allow the layers to separate – the cyclohexane should form a purple layer (as the iodine is now dissolved in it) on top of the aqueous layer.
This step means that the cyclohexane/iodine is clearly separated from the impure aqueous layer (it will be obvious because the top layers strong purple colour and the bottom layer clear colour).
You must make sure you allow the two layers to separate, if they do not completely separate or the colours are incorrect then the experiment will have to be started again.
7. Place a beaker underneath the separating funnels tap, then open the tap and remove all of the bottom aqueous layer, leaving the purple layer in the funnel. Discard of this aqueous layer down the sink.
This method of solvent extraction removes the unwanted aqueous layer, leaving the purple
Iodine Extraction
Equipment:
Goggles
Fume cupboard
2X 250cmᶾ beaker
Filter funnel
Filter paper
Separating funnel
Bunsen burner
Tripod
Gauze
Method:
1. Set up the equipment with the Bunsen burner and tripod on the heatproof mat with the gauze on top of the tripod.
2. Add the seaweed to the tin lid and place on top of the gauze (try not to use any ‘pods’ of seaweed as they pop when heated which could be dangerous). Light the Bunsen burner and heat the seaweed in the tin lid on the blue flame until it has all been reduced to ash.
This step involves heating the seaweed so it is reduced to ash to extract the iodine (in which it is present as an iodide) and make it easier to incorporate with …show more content…
Next add 2cmᶾ of dilute sulfuric acid to the remaining solution and then add 10cmᶾ of hydrogen peroxide solution. This should create a deep brown colour of iodine as the hydrogen peroxide and iodide ions oxidise.
This step allows the hydrogen peroxide and iodide ions to oxidise, creating iodine, which is needed in the next stage.
Ensure that the sulfuric acid does not come into contact with the skin. When the hydrogen peroxide is added to the solution it should turn brown, if it doesn’t the experiment will need to be restarted.
5. Transfer the mixture to a separating funnel and add 10cmᶾ of cyclohexane. Stopper the separating funnel and secure with your thumb. Ensure the tap is closed fully then shake the funnel for 30 seconds. Turn the funnel upside down and open the tap to release the pressure build up.
The iodine created in the previous stage is soluble in cyclohexane which means they can become one layer and any impurities can be separated and stay in the aqueous layer …show more content…
You must keep your thumb over the stopper when shaking the funnel as the stoppers can sometimes be loose and you don’t want to lose any of the liquid. It is very important that you open the tap and release the gas that builds up it the separating funnel and it will put pressure on the funnel and it could crack if not released.
6. Close the tap again and set up the funnel on a clamp stand. Allow the layers to separate – the cyclohexane should form a purple layer (as the iodine is now dissolved in it) on top of the aqueous layer.
This step means that the cyclohexane/iodine is clearly separated from the impure aqueous layer (it will be obvious because the top layers strong purple colour and the bottom layer clear colour).
You must make sure you allow the two layers to separate, if they do not completely separate or the colours are incorrect then the experiment will have to be started again.
7. Place a beaker underneath the separating funnels tap, then open the tap and remove all of the bottom aqueous layer, leaving the purple layer in the funnel. Discard of this aqueous layer down the sink.
This method of solvent extraction removes the unwanted aqueous layer, leaving the purple