Question

A 230 g sample of a compound contains 136.6 g of carbon. 26.4 g of hydrogen, and 31.8 g of nitrogen. The rest is oxygen. What is the mass percent of oxygen in the compound?

Answer 1

`((230-136.6-26.4-31.8)*g)/(230*g)` `xx` `100%` `=` `??%`

Explanation:

The mass of oxygen in the `230` `g` sample is simply that mass that is not `C`, `H`, or `N`. So I simply subtract from the starting mass and the balance must be oxygen.

In fact there are few ways that an analyst can measure oxygen. Typically, a sample containing `C,H,N,O` will be presented, and the percentage `C`, `H`, `N` will be reported. The percentage `O` is the percentage not accounted for is assumed to be oxygen.