Question

A 17g sample of H2O2 was decomposed to yield 1g of H2 and 16g of O2 An unknown sample containing only H and O was decomposed to yeild 2g of H2 and 16 g of O2. The formula for the unknown sample is:

Answer 1

Answer:

Explanation:

Our $H_2O_2$ sample yielded 1g of $H_2$ and 16g of $O_2$, but our unknown sample yielded 2 times as much $H_2$  for the same amount of $O_2$.

What does this mean? that the H:O proportion for the unknown sample is twice the H:O proportion for the $H_2O_2$ sample.

What is the  H:O proportion for the $H_2O_2$ sample? As we can see from its formula, it's 1:1, therefore the proportion for the unknown formula must be 2:1.

That means, two H atoms for every O atom. We could write that as: $H_2O$ and you should recognize that formula, for it is one of the most common compounds on earth, Water.