Question

According to the following reaction, how many moles of iron(III) chloride will be formed upon the complete reaction of 22.7 grams of iron with excess chlorine gas?

2 Fe (s) + 3 Cl2 (g) = 2 FeCl3 (s)

Answer 1

So you're going to need to do stoichometry for this. It helps to think of it as a recipe. With 2 moles of iron, and 3 moles of chlorine, you can make 2 moles of iron chloride. Do you already understand the relation of moles to mass?

Answer 2

So it's kind of like saying that you need two dozen eggs to make 100 pancakes, but you don't have two dozen eggs, you have 5 individual eggs. So you need to convert. The "recipe" tells you that you need two moles of iron, but you don't have moles, you have mass.

Answer 3

The way I always start these out is by writing what unit I need my final number to be. What are the units of your final number?

Answer 4

Yeah but what units will your final number be in? It's asking how many moles of iron chloride can you make. So I would write that your final value needs to be in moles of FeCl3

Answer 5

That isn't the answer I got

Answer 6

We know moles of FeCl3 is going to be our final number, so what we do has to end with moles FeCl.

Answer 7

We know that we have 22.7g Fe. Looking at a periodic table, we see that Fe has a mass of 55.85g for every mole.

Answer 8

since our final number should be moles, we can convert that now. How many moles of iron do you have with 22.7g of iron?

Answer 9

1 mole of iron is equal to 55.85g. We have 22.7g.

Answer 10

That's right! To cancel out the grams, you need to divide by grams, and then you are left with moles!

Answer 11

It is, but do you know why?

Answer 12

Awesome, thats the answer

Answer 13

Sure

Answer 14

According to the following reaction, how many moles of iron(II) chloride will be formed upon the complete reaction of 21.7 grams of iron with excess hydrochloric acid?

Fe (s) + 2 HCl (aq) = FeCl2 (aq) + H2 (g)

Answer 15

So we have a very similar problem. They want your answer to be in "moles of iron(II) chloride)" and you are given an initial mass of one reactant. Since HCl is in excess, we don't have to worry about it.

Answer 16

So you have 21.7 grams of iron, how many moles is that?

Answer 17

.3885407341

Answer 18

That's right, you have .3885407341 moles of iron. An you know that for every one mole of iron, you can get one mole of FeCl2...

Answer 19

so this is the anser right

Answer 20

Yup!

Answer 21

thanks I understand it now

Answer 22

No problem! But I'm sure you're gonna have to factor sig. figs. into your answer. Don't forget to take that into account!