You are Here: Home

# gcse chemistry: empirical formula, help! watch

analysis of a compound found it contained:
13.0% chlorine (Cl)
2.2% carbon (C)
8.8% oxygen (O)

what is the empirical formula of this compound?

relative atomic masses: C=12, O=16, Cl=35.5, Pb=207
2. u divide each thing by its relative atomic mass:
Pb: 76/207 = 0.367
Cl:13/35.5 = 0.366
C: 2.2/12 = 0.183
O:8.8/16 = 0.55

Then u divide each by the smallest:
Pb: 0.367/0.183 = 2
Cl: 0.366/0.183 = 2
C: 0.183/0.183 = 1
O:0.55/0.183 = 3
so the empirical formula is : Pb2Cl2CO3
3. the empirical formula is the simplest whole ratio of the atoms of each element in a compound

STEPS TO WORK IT OUT:
1) divide each % by the relative atomic mass (e.g. 76/207)
2) with the results obtained in 1) ... divide each result by the smallest result obtained
3) this should give you a ratio in moles of each element!

hope this helps!
4. Divide the percentages by their relative atomic masses. When you have those answers, find the smallest one and divide all the answers by that.
5. Thanks!!! that really helped, it was easier to understand than my revision guide.
6. :- Yeah it's Pb2Cl2O3

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: December 28, 2010
Today on TSR

### Top unis in Clearing

Tons of places at all these high-ranking unis

### Why do women like men in suits?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE