[CStrike18]

this is the question i am having trouble on  can anyone help?

Q:Iron(III)chloride can be produced by reacting Iron(III)oxide with hydrochloric acid. how many millimeters of a 6.00M HCl solution are needed to produce 3.25g of Iron(III)chloride?

A: i have no worldly idea of where to even start ..help

[chrisbb]

How about something simple: a reaction equation?

Fe₂O₃  + HCl --> ?

[CStrike18]

Fe₂O₃ +6HCl --> 2FeCl₃ + 3H₂O   (I think)

[chrisbb]

LOL!
I missread that!

You are correct!
OK, so now we have the correct formula, what is the next item you can find? If you are stuck in a question what is the first thing you can try and find (other than the rxn equation)?

[Arkcon]

Fe₂O₃ +6HCl --> 2FeCl₃ + 3H₂O   (I think)

Great, now, the units of a chemical equation are moles.  You've been given a quantity of HCl in molarity and product in grams, you'll have to convert  the units.

[CStrike18]

do i convert the 3.25g into moles then plug that and the 6.00M HCl in the Molarity equation?

[enahs]

How many mols of the Iron compound do you have?

If you have that many mols, according to you balanced equation, how many mols of HCl is required? How many mL of HCl at the given molarity is required to have that many mols of HCl?

[CStrike18]

Molarity = amount of solute divided by the volume of the solvent

 i have the Molarity but i dont have either of the amount or the volume so thats where i am stuck

[enahs]

Molarity = amount of solute divided by the volume of the solvent

Correct.

Irrelevant, but correct.

How many molEs of Iron(III) Chloride do you have? It is a solid, it is not a molarity, just the number of molEs.

So let us pretend you have 1 molE of Iron(III) Chloride. According to your balanced chemical equation, how many molEs of HCl are required? What volume of 6M HCl supplies that number of molEs?

Now, do the same thing, but with your data.

[CStrike18]

to make 2 moles of FeCl₃ i need 6 moles of HCl... or do i take the 3.25g of FeCl₃ and convert it to Moles?

[enahs]

to make 2 moles of FeCl₃ i need 6 moles of HCl... or do i take the 3.25g of FeCl₃ and convert it to Moles?

Yes.

How many mol's of FeCl3 do you have? How many mols of HCl are required to completely react with that amount of FeCl?

[CStrike18]

converting 3.25g of FeCl₃ gives me .02 mols of FeCl₃

[enahs]

Good. So if you have 0.02 mols of FeCl₃, how many mols of HCl were required?

What volume of 6M HCl supplies that amount of mols?

[CStrike18]

i dont remember how to do that 
but once i have the moles of it i can convert from moles to volume but then i need the density of HCl right?

[Borek]

to convert from moles to volume i need the density of HCl right?

No, density is necessary when converting between molarity and percent concentrations. There is no need for density here.

Write down formula of molar concentration and solve it for volume.