So, you would first start by finding the molar mass of CuBr2.
Mass of Cu: 63.546
Mass of Br: 79.904
So you take the molar mass:
1(63.546) + 2(79.904) = 223.354
(Remember there’s a 2 in front of the of Br due to its subscript.)
After taking the molar mass, you can start solving for percent compositions.
To find percent compositions, it’s
(Part / Whole) X 100
So for the of Cu:
(Mass of Cu/ Molar Mass) X 100
(63.546/223.354) X 100 = 28
So it would be 28% for Cu’s percent composition
Percent composition of Br:
Remember, Br is a diatomic so there’s a subscript of 2.
{2(79.904) / 223.354} X 100 = 71.5
So it would be 71.5% for Br2’s percent composition.
Hope this helps!
