# Chemistry question on mole ratios

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#1
The question is:
The word equation for the reaction is:
iron + chlorine → iron chloride

The teacher weighed:
• the glass tube
• the glass tube and iron before the reaction
• the glass tube and iron chloride after the reaction.
Table 6 shows the teacher’s results.

Table 6
Mass in g
Glass tube 51.56
Glass tube and iron 56.04
Glass tube and iron chloride 64.56

Calculate the simplest whole number ratio of:
moles of iron atoms : moles of chlorine atoms
Determine the balanced equation for the reaction.
Relative atomic masses (Ar): Cl = 35.5 Fe = 56

I know that the balanced symbol equation is 2Fe+3Cl --> 2FeCl3
and i've calculated the Mr for all. I also know that moles= mass divided by Mr. Just not sure how to put it all together and confused about the glass tubes. Any help would be greatly appreciated.
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1 year ago
#2
So first you should be working out the number of moles of iron she has in the tube
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1 year ago
#3
try looking here:
https://www.science-revision.co.uk/m...20formula.html

it might help
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#4
0.5 moles? I did the mass of iron in the tube divided by the Mr of iron in the reactants. Is that right?
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1 year ago
#5
(Original post by Elisabeth3210)
0.5 moles? I did the mass of iron in the tube divided by the Mr of iron in the reactants. Is that right?
You are over complicating it.

Just start at the beginning.
She has a mass of iron in the tube (forget about everything else)
: how many moles of iron does she have?
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#6
2?because thats how much iron is in the balanced equation? I'm not very good at chemistry
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#7
Can you help?
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1 year ago
#8
(Original post by Elisabeth3210)
Can you help?
Questions like these the point of them is to get the formula, not using it to work out anything.

So start from the beginning:
You have a mass of iron. And the MR of iron.
How do you find the number of moles from those two bits of information?
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#9
moles= mass/ MR
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1 year ago
#10
(Original post by Elisabeth3210)
moles= mass/ MR
Perfect.
So what do you get for your calculation?
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#11
so is the mr of iron 112 because its 2 Fe
am I using the mass of iron in the glass tube?
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1 year ago
#12
(Original post by Elisabeth3210)
so is the mr of iron 112 because its 2 Fe
am I using the mass of iron in the glass tube?
Mr of Iron is given to you in the question = 56.

And yes the mass of iron in the glass tube.
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#13
the mass of iron is 4.48g because i did the mass of iron in the glass tube- the mass of the glass tube
so the moles are 0.08 ?
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#14
Is this answer a ratio of 1:3, i think i was really overcomplicating it. I got the moles of chlorine as 0.24
or am i completely wrong?
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1 year ago
#15
(Original post by Elisabeth3210)
the mass of iron is 4.48g because i did the mass of iron in the glass tube- the mass of the glass tube
so the moles are 0.08 ?
Perfect well done!!
Okay, so next step is to work out the number of moles of chlorine.
Can you work that out?
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1 year ago
#16
(Original post by Elisabeth3210)
Is this answer a ratio of 1:3, i think i was really overcomplicating it. I got the moles of chlorine as 0.24
or am i completely wrong?
Absolutely spot on!
And then you use that ratio to make the formula (which you already knew but this is how you worked it out) 😀
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#17
Thank you for sticking with me!! the formula just really confused me but it was much simpler than i though! Have a fantastic rest of your day
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#18
So the formula i put of 2Fe+3cl -> 2FeCl3 is right?
I dont understand how that reflects the ratio, i just already know the balanced equation for that reaction.
sorry for another question
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1 year ago
#19
(Original post by Elisabeth3210)
So the formula i put of 2Fe 3cl -> 2FeCl3 is right?
I dont understand how that reflects the ratio, i just already know the balanced equation for that reaction.
sorry for another question
Okay so the ratio you worked out shows you the formula for iron chloride 1:3
FeCl3

And then you make the equation adding Iron to Chlorine to make FeCl3 and balance it.
Last edited by GabiAbi84; 1 year ago
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#20
ohhh ok, thanks again for all the help, i appreciate it more than you realise!!
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