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REDOX TITRATION, determining RMM of iron salt?

I am struggling to figure out how to determine the RMM of iron salt.

Ive determined the mass of iron in the salt itself via titration, and ive calculated the percentage of fe2+ in the iron salt.

I know the moles of fe2+ in the iron salt but how do I calculate the RMM of the iron salt?

thanks in advance

Reply 1

Pigster

If 50% of your salt was Fe2+ then the RMM of the salt must be 2x (1/50%) the RAM of Fe.

Reply 2

hurricaneee

I don't understand how you got to that pigster :colondollar:

I got 1.83g/2.76g x 100% - 66.3% of fe2+.....

Reply 3

Pigster

If 66.3% of the mass 1 g of salt was due to Fe, 0.337 g must be due to X2-.

It also means that 66.3% of the Mr must be due to Fe.

i.e. 66.3% of the Mr must be 55.8.

1/0.663 x 55.8 = your answer.

Reply 4

hurricaneee

Thanks pigster, what I dont understand is how by using the mr of Fe, that you can find out the unknown part of the salt...

thanks again

Reply 5

Pigster

Do you know the Mr of the entire salt?

Subtract off the Ar of Fe, which gives you the Mr of the rest.

Do you have an idea of what the rest is - knowing the Fe is 2+ should help you, i.e. if the rest had a mass of 71, it's likely to be Cl as there needs to be 2x.

BUT, it'll just be an educated hunch, unless you have more information.