# 1% iron solution?

1. Dec 16, 2009

### lesieux

1% iron solution??

1. The problem statement, all variables and given/known data

Dissolve 1.70g of iron III chloride in 99 ml of distilled water. Mix well and label 1% iron.

2. Relevant equations

I've tried to check the value of the iron percentage but I don't succeed.

3. The attempt at a solution

First I've tried to find out the number of mole of FeCl3,6H2O (M=270g.mol-1) in 1.70 g and found the mass of iron 0.352 g then divide this mass by the total mass (1,7+99), but it doesn't work. Could anyone help me? Thanks in advance.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 16, 2009

### Staff: Mentor

Re: 1% iron solution??

This will be 1% in FeCl3, not Fe.

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3. Dec 16, 2009

### lesieux

Re: 1% iron solution??

The protocol is here
http://dwb4.unl.edu/Chem/CHEM869K/CHEM869KMats/SimpleIronLab.html
And i still don't understand "Dissolve 1.70g of iron III chloride in 99 ml of distilled water. Mix well and label 1% iron."
Could anyone show me the calculation to check the 1% iron.

4. Dec 17, 2009

### chemisttree

Re: 1% iron solution??

You are going to determine iron in what form? You are going to report iron as Fe or Fe2O3 or FeCl3? I've got a feeling that you won't be reporting iron as FeCl3. Find out the form you need and ratio the molecular wt to that of FeCl3.

I'm guessing that it will be something like 1.7.

5. Dec 17, 2009

### lesieux

6. Dec 17, 2009

### Staff: Mentor

Re: 1% iron solution??

That could be accidental, but to prepare 1% w/w FeCl3 solution you need to dissolve 1.7 g (more precisely 1.68 g) of FeCl3.6H2O in appropriate amount of water.

I wrote concentration calculator just to be able to check such things on the fly...

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7. Dec 17, 2009

### lesieux

Re: 1% iron solution??

I'm sorry to ask you this question.
It may be obvious but as i didn't succeed.
Would you mind showing me the calculation?

8. Dec 17, 2009

### Staff: Mentor

Re: 1% iron solution??

Basically you have to calculate what is mass of FeCl3 in 1.7g FeCl3.6H3O. Start calculating their molar masses. 1 mole of FeCl3.6H3O contains how many moles of FeCl3?

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9. Dec 18, 2009

### chemisttree

Re: 1% iron solution??

Assume that the FeCl3 is anhydrous.

You are asked to label it 0.10 M, not 1%, right? If that is the case, then you are on the right track. Be sure to carefully weigh the FeCl3 and label it accordingly. You might not need to measure it out to three or four decimals, but you should do so in your calculations.

Remember that moles = grams/formula wt. and that concentration (M) = moles/volume(L)