## Exercise M.21

Johana Jeon 1A
Posts: 30
Joined: Sun Feb 12, 2017 3:00 am

### Exercise M.21

In M.21: A compound found in the nucleus of a human cell was found to be composed of carbon, hydrogen, oxygen, and nitrogen. A combustion analysis of 1.35g of the compound produced 2.20g of CO2 and 0.901g of H2O. When a separate 0.500-g sample of the compound was analyzed for nitrogen, 0.130g of N2 was produced. What is the empirical formula of the compound?

How do we find the empirical formula? In the solutions manual it says:

4.45g C x (1mol C/12.01g C) = 3.71mol x (1/1.38mol) = 2.69 x 8.07
7.48g H x (1mol H/1.0079g H) = 7.42mol x (1/1.38mol) = 5.38 x 3 = 16.1

I was wondering where they got the 1.38 from?

Chem_Mod
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### Re: Exercise M.21

22.0% is oxygen.
Therefore 22.0 g is oxygen.

$\frac{22.0 g}{16.00 g.mol^{-1}}=1.375=1.38$