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Helppp:S it probably is so simple but im too busy stressin out..

groovyangel2008

5 (a) Compound A (Mr = 82) contains 87.8% carbon and 12.2% hydrogen by mass. Using the
data provided, show that the molecular formula of A is C6H10.
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(3 marks)

Thank you so much :smile:

Reply 1

Kyalimers

Empirical Formula and Molecular Formula!!

Reply 2

EierVonSatan

87.8% of the total mass is carbon so 82/100 x 87.8 = 72, divide by 12 (Carbon Ar) gets you 6 carbons. For hydrogen 82/100 x 12.2 = 10, divide by 1 gets you 10 hydrogens.

Reply 3

RMIM

I think EierVonSatan has used a better method (quicker for this question)

treat the % as grams

C 87.8/12 :h:

12.2/1

C7.31 : H12.2

divide by smaller no.

C1 :h:

1.667

recognise 0.667 is 2/3

C1: H 1 2/3

multiply by 3/2

C1.5 : H2.5
3C : 5H (empirical formula)

12*3=36
1*5=5

total 41.
82/41=2
molecular formula
C6H10