# If 3.907 g carbon combines completely with 0.874 g of hydrogen to form a compound, what is the percent composition of this compound?

##### 2 Answers

#### Answer:

#### Explanation:

And, of course for a binary compound,

#### Answer:

The compound contains

#### Explanation:

We know

The mass of the compound must be the sum of the masses of

The formula for percent by mass is

#color(blue)(bar(ul(|color(white)(a/a)"% by mass" = "mass of element"/"mass of compound" × 100 %color(white)(a/a)|)))" "#

NOTE: You could have gotten the

That method is simpler, but I prefer using the first method.

If you make a mistake in calculating

The first method does not depend on the