Here is a worked example of a stoichiometry problem. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html
How many molecules of oxygen are produced from the decomposition of 8.75 g of hydrogen peroxide in the following equation Mg + H2O2 --> MgH2 + O2
options:
8.75 x 1024
6.02 x 1023
1.55 x 1022
5.27 x 1024
1.55 x 1023
2 answers
8.75/34.02 (molar mass of H2O2) = .257 mol H2O2
Since the mol ratio b/t H2O2 and O2 is 1:1, there is also .257 mol O2
.257 mol * 6.02 * 10^23 = 1.55 * 10^24 molecules so the 3rd option.
Since the mol ratio b/t H2O2 and O2 is 1:1, there is also .257 mol O2
.257 mol * 6.02 * 10^23 = 1.55 * 10^24 molecules so the 3rd option.