# AS Chemistry questionWatch

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#1
Empirical formula

Hello, can someone explain this ratio to me?
Element: C | H
Percentage: 83.7 | 16.3
Molecular mass: 12 | 1
Moles: 6.975 | 16.5
The empirical formula is C3H7 because the ratio is 3:7
Sorry i'm really bad at maths.
0
4 weeks ago
#2
(Original post by mspaghetti)
Empirical formula

Hello, can someone explain this ratio to me?
Element: C | H
Percentage: 83.7 | 16.3
Molecular mass: 12 | 1
Moles: 6.975 | 16.5
The empirical formula is C3H7 because the ratio is 3:7
Sorry i'm really bad at maths.
If you divide both values you got for your moles by the smallest value, you get 1:2.333

For empirical formulae, you want the smallest whole number values, so you need to get rid of that 0.333.

Hopefully, you'll recognise the 0.333 at 1/3, so it is easy to get rid of the 0.333, by multiplying both sides by 3.

1
#3
(Original post by Pigster)
If you divide both values you got for your moles by the smallest value, you get 1:2.333

For empirical formulae, you want the smallest whole number values, so you need to get rid of that 0.333.

Hopefully, you'll recognise the 0.333 at 1/3, so it is easy to get rid of the 0.333, by multiplying both sides by 3.

wow, thank you.
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