# chemistry formulae help

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#1
butane has the formula C4H10.
calculate the mass of carbon in 100g of butane.
relative atomic masses: H=1.00, C=12.0
relative formula mass: C4H10=58.0
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6 months ago
#2
Do you know a formula that can be rearranged for mass?
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6 months ago
#3
Write a combustion equation and balance it
Moles of carbon dioxide=moles of carbon
Convert moles of carbon to mass
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#4
(Original post by 5hyl33n)
Do you know a formula that can be rearranged for mass?
My chemistry teacher has referred us to this page, so maybe one of these? If you can’t zoom in i can send another picture.
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6 months ago
#5
The picture is fine. So in all of these equations you are using the formula:

Moles = Mass/Mr
Last edited by 5hyl33n; 6 months ago
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6 months ago
#6
58.0 is the mass of one mole of butane.
To find the number of moles of butane in 100g used n=m/mr, 100/58.0 = 1.72
There are 1.72 moles of butane in 100g.
Multiply (4x12) by 1.72 and that should give you the answer.
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6 months ago
#7
(Original post by XHannahR)
58.0 is the mass of one mole of butane.
To find the number of moles of butane in 100g used n=m/mr, 100/58.0 = 1.72
There are 1.72 moles of butane in 100g.
Multiply (4x12) by 1.72 and that should give you the answer.
Could you not give the full working out, please? That doesn't help OP.
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6 months ago
#8
Well, there is no point in explaining that anymore...

However OP, read through the working out and try and practise another similar question without looking back at the above method. See if you can remember it without any assistance. Hopefully, the above working makes sense.

Let us know if you need anymore help on any other question.
Last edited by 5hyl33n; 6 months ago
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6 months ago
#9
Here’s the written working as @5hyl33n asked for:
Last edited by XHannahR; 6 months ago
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6 months ago
#10
(Original post by Plantagenet Crown)
* Moles = Mass/Mr
Ah yes, I just spotted my mistake!
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