The molecular formula of chloroform is CHCl3. This means that each molecule of chloroform contains one carbon atom, one hydrogen atom, and three chlorine atoms.
The molar mass of chlorine is approximately 35.5 grams per mole.
The molar mass of chloroform can be calculated by adding the molar masses of each atom in the molecule:
Molar mass of chloroform = (1 x molar mass of carbon) + (1 x molar mass of hydrogen) + (3 x molar mass of chlorine)
= (1 x 12.01 g/mol) + (1 x 1.01 g/mol) + (3 x 35.45 g/mol)
= 12.01 g/mol + 1.01 g/mol + 106.35 g/mol
= 119.37 g/mol
Now, we can calculate the percent by mass of chlorine in chloroform:
Percent by mass of chlorine = (mass of chlorine in chloroform molecule / molar mass of chloroform) x 100%
= (3 x molar mass of chlorine / molar mass of chloroform) x 100%
= (3 x 35.45 g/mol / 119.37 g/mol) x 100%
= 89.93%
Therefore, approximately 89.93% by mass of a chloroform molecule is composed of chlorine.
