How to Make Mohr's Salt: Water and Solution Amounts Needed?

[jsmith613]

When making Mohr's Salt (Ammonium Iron (II) Sulphate) how much water am I required to add OR how much of each solution must I use.

Thanks

Assuming it is equimolar, how much of each (Iron Sulfate and Ammonium Sulphate) Do i need

 

[Borek]

Start with synthesis reaction equation.

 

[jsmith613]

Start with synthesis reaction equation.

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The reactions are:

Fe + H2SO4 --> FeSO4 + H2

NH3 + HSO4 --> (NH4)2SO4

But i know that the FeSO4 should be hydrated (FeSO4-7H2O) - how is this achieved

 

[Borek]

Reaction takes place in water, so there is no problem with water source, don't you think?

Main problem is how to calculate amount of iron, ammonia and sulfuric acid. But it is not that difficult. Two possible ways - one, write total reaction of synthesis (that is, but ammonia, iron and sulfuric acid on the left, Mohr's salt on the right) and do simple stoichiometry. Second - how many moles of iron per 1 mole of Mohr's salt? How many moles of ammonia? Of sulfuric acid? Can you use this information to calculate how much of each reactant you will need to produce 1 mole of Mohr's salt?

 

[jsmith613]

Reaction takes place in water, so there is no problem with water source, don't you think?

Main problem is how to calculate amount of iron, ammonia and sulfuric acid. But it is not that difficult. Two possible ways - one, write total reaction of synthesis (that is, but ammonia, iron and sulfuric acid on the left, Mohr's salt on the right) and do simple stoichiometry. Second - how many moles of iron per 1 mole of Mohr's salt? How many moles of ammonia? Of sulfuric acid? Can you use this information to calculate how much of each reactant you will need to produce 1 mole of Mohr's salt?

Fe + H₂SO₄ --> FeSO₄-6H₂O + H₂

NH₃ + H₂SO₄ --> (NH₄)₂SO4

We have 1 mole of Iron in the Iron (II) salt and 1 mole of sulphate
In the Ammonium salt, we have 2 moles of ammonium and one mole of sulphate.

Does that mean we need 1 mole of FeSO4 and 1 mole of (NH4)₂SO4

 

[Borek]

Yes. But from your equations I got the impression that you start not with sulfates, but with iron and ammonia.

 

[jsmith613]

Yes. But from your equations I got the impression that you start not with sulfates, but with iron and ammonia.

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Of course, I am preparing a double salt from scratch - is this problamatic