# Question #b9862

Jan 15, 2014

Copper (II) Chloride or $C u C {l}_{2}$
has a percent composition based upon the relative masses of the copper and chlorine found in the molar mass or gram formula mass of the molecule.

There is one atom of copper for every two atoms of chlorine in this molecule.

First we will find the molar mass (gfm) of the molecule.

copper has a mass of 63.5 amu (from the periodic able)
chlorine has a mass of 35.45 amu (from the periodic table)

Cu 1 x 63.5 = 63.5
Cl 2 x 35.45 = 70.9

63.5 + 70.9 = 134.4 g/mol

Now find the percent ration by dividing the mass of each element by the total mass of the molecule.

Cu 63.5 / 134.4 = .472 or 47.2%
Cl 70.9 / 134.4 = .528 or 52.8%

Therefore the percent composition of $C u C {l}_{2}$ is 47.2% copper and 52.8% chlorine.

Here is a video I made on YouTube for determining percent composition

Here is an additional video on determine gram formula mass.