Question

1.how many molecules are contained in a 5.85 g sample of dimethylmercury

2. what is the percentage of mercury (by mass) in the sample

Answer 1

1) The molar mass of dimethyl mercury is 230.6 g/mol.

The no. of moles of dimethylmercury in 5.85 g is given by mass/molar mass = 5.85/230.6 = 0.0253 mole

We know that 1mole of sample contain 6.023x10^23 molecules

Then 0.0253 mole of dimethylmercury contain 0.0253mol * 6.023x10^23 molecules = 1.527*10^22 molecules

2) The molar mass of dimethyl mercury is 230.6 g/mol.

The percent of mercury in dimethyl mercuy is given by

atomic weight of mercury / number of Hg atoms in one dimethyl mercury molecule

% Hg = 200.6x1 / 230.6 = 87%.