To find the percent composition of a compound, divide an element's molar mass by the molar mass of the whole compound. Then multiply by 100 since it's a percent. You do the same for other elements in the compound. When finished with the calculations, all the percents added together should equal near 100%
[tex] \frac{Molar Mass Of Element}{Molar Mass Of Compound} * 100[/tex]
Molar mass of Cu(copper) is 63.546 g/mol
Molar mass of Br(bromine) is 79.904. Since it is Br2, we must multiply the molar mass of bromine by 2, making it 159.808 g/mol
Molar mass of the whole compound is 223.354 g/mol
Percent Composition of Cu = [tex] \frac{63.546}{223.354} * 100 = 28.45[/tex]%
Percent Composition of Br2 = [tex] \frac{159.808}{223.354} * 100 = 71.55[/tex]%
So, the answer is 28.45% Cu and 71.55% Br2.
To make sure it's correct, i'll add both percents to see if its near 100%
28.45% + 71.55% = 106% which is near 100%.
