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Empirical formula and molecular formula

So I'm a little stuck on two questions, firstly I calculated the empirical formula of a compound which was C2H4Cl and now I need to find the molecular formula so I did the relative empirical mass (89.3) then divided the actual formula mass (127) but that gave me 1.422172452 so I'm confused as to what to scale up by, just 1 so it stays the same?

Next question is the same but the empirical formula so far is 1, 3 and 1.34, so should I multiply them all by 3 to get 3, 6 and 4?

Thanks! :smile:
Check your emperical formula mass. There's a mistake, I reckon

The rest seems fine.
Original post by Qaiys
So I'm a little stuck on two questions, firstly I calculated the empirical formula of a compound which was C2H4Cl and now I need to find the molecular formula so I did the relative empirical mass (89.3) then divided the actual formula mass (127) but that gave me 1.422172452 so I'm confused as to what to scale up by, just 1 so it stays the same?

Next question is the same but the empirical formula so far is 1, 3 and 1.34, so should I multiply them all by 3 to get 3, 6 and 4?

Thanks! :smile:


It would be a lot more helpful and easier if you upload the Q, so we can see where you went wrong :smile:
Reply 3
Original post by TheNoobishKnight
It would be a lot more helpful and easier if you upload the Q, so we can see where you went wrong :smile:


Hahaa okay, sorry here it is :biggrin:

1) A halogenoalkene, H, has relative formula mass 127 and the following comp by mass: C:37.8% H:6.3% Cl:55.9%
Show that the empirical formula oh H is C2H4Cl (Which I did okay)

Then deduce molecular mass.

Thanks! :smile:


**EDIT** The second one's okay now, I divdied by 12 instead of 16 for O, sorry! Just number 1 :biggrin:
(edited 9 years ago)
Original post by Qaiys
Hahaa okay, sorry here it is :biggrin:

1) A halogenoalkene, H, has relative formula mass 127 and the following comp by mass: C:37.8% H:6.3% Cl:55.9%
Show that the empirical formula oh H is C2H4Cl (Which I did okay)

Then deduce molecular mass.

Thanks! :smile:


**EDIT** The second one's okay now, I didividedy 12 instead of 16 for O, sorry! Just number 1 :biggrin:


So you did N=Mass/M for all of them?
37.8/12=x
Did you then divide it by the smallest and get ratios?
I hope I am right, as I am a bit rusty -_-
Reply 5
C2H4Cl = (2 x 12) + (4 x 1) + 35.5 = ?
Reply 6
C2H4Cl has an Mr of 63.5

Pah. Beaten by two minutes.
Reply 7
Hahaa yup for some reason I had Cl as 59.5 ;/ thanksss everyone :biggrin:

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