Question

What is the percentage composition of $PbC{{l}_{2}}$?

Answer 1

First, find the atomic masses of the elements present in the given compound, then, find the molecular mass of the compound. Then to find the percentage composition of the elements present in the compound by dividing the mass of the atom by the mass of the molecule and multiply it by 100.

Complete answer:
The percentage composition of a compound is used to determine the amount of each element present in the compound. So, to find the percentage composition, first, find the atomic masses of the elements present in the given compound, then, find the molecular mass of the compound. Then to find the percentage composition of the elements present in the compound by dividing the mass of the atom by the mass of the molecule and multiply it by 100.
The given compound in the question is $PbC{{l}_{2}}$, so there are two elements present, i.e., lead and chlorine. The atomic mass of lead is 207.19 grams/ mol and in the compound, there is only one atom of $PbC{{l}_{2}}$, so the mass will be 207.19 grams/ mol. The atomic mass of a chlorine atom is 35.453 grams/ mol and in the compound, there are two atoms of chlorine atoms, so the mass will be 70.906 gram/ mole.
So, the mass of $PbC{{l}_{2}}$will be:
Mass = 207.19 + 70.906 = 278.106 grams.
The percent composition of lead will be:
$Pb=\dfrac{207.19}{278.106}\text{ x 100 = 74}\text{.504 }\\!\\!$
The percent composition of chlorine will be:
$C{{l}_{2}}=\dfrac{70.906}{278.106}\text{ x 100 = 25}\text{.496 }\\!\\!$
The percent composition of lead is 74.504 and the percentage composition of chlorine is 25.496.

Note:
When we calculate the mass of the compound, then, don’t forget to multiply with the number of atoms present in the compound because this step is an important step for further calculation.