To prepare a standard solution of Ammonium Iron Sulfate and use this to this to standardise a solution of Potassium Permangernate

Potassium permangenate

• Oxidising agent

• Purple solid

• Not a primary solid (not available in high purity decomposes in light and heat

• Acts as an oxidising agent in the presence of a Hplus ion

What is used to acidify potassiumm permangenate

Sulfuric acid

• Cl in HCL would be oxidised if it was used #

• Nitric acid is also a strong oxidising agent so it cant be used

What happens in neutral or basic reactions

The above reaction doesnt happen instead MN7 plus purple we get MN2 plus colourless we get an intermediate oxidisation state mn 4 plus

WHat colour is formed in MN4+

MN 4+ appears brown due to the formation of magnesium oxide

Ammonium iron sulfate

This is used as the primary standard solution as it has a high molecular mass and is stable in air even though it isngt anhydrous

During the experiment there are two additons of dilute H2SO4 (sulfuric acid)

1- |When dissolving crystals in water to make the standard solution some dilute H2So4 is added to the water to prevent the FE 2 to ooxidising to fe 3 due to oxygen in the air and the water

2 - Just before beginnin the titration dilute H2So4 is added to the connical flask containing the f3 2 this ensures the full reduction of MN 7 to Mn 2 and prevent the formation of the brown percipiatet

solution used to standardise

Ammonium sulfate

Colour change detected

first permamnent pale pink

why is dilute sulfuric acid used when preparing the standard solution of from hydrated amonium iron sulfate

to prevent the oxidisation of Fe2 and allow for the full reduction of MN7 t0 Mn2 and prevent the formation of a brown precipitate

Two procedures to ensure accuracy in the end point concerning the connical flask

• rinse the flask with deoinised water

• Keep burette vertical

• carry out rough titre discard titre of 0.1

Precaution taken towards the end point

• add drop by drop slowl

• swirl the contens

What is one mole

One mole is equivalent to the molecular mass of a substance which is also equal to the grams

To find how many moles in a certain quantity

Divide the moles by the quantity its in then multiply by the quantity want to find

Trying to calculate the amount of moles required to oxidise the iron

check the leftn handside and check the molar ratio

Molarity - Moles per litre

Molarity is calculated by dividing the moles of something by the volume its in by litres

why is deoinised water used instead of distilled water

deoinised water could contain non ionic substrances thta could be oxidised or reduced intefer with the result sof thye experiemtnn furthermore dearillwd water is purer than deionised water