Question

How many molecules are contained in a 7.10-g sample of dimethylmercury?

What is the percentage of mercury (by mass) in the sample?

Answer 1

Dimethylmercury is (CH3)₂Hg

Molar mass of (CH3)₂Hg = 230.66 g

mass = 7.1 g

number of moles = mass /molar mass

                              =7.1/230.66

                              =0.031 mol

Number of molecules = Avogadro's number * number of moles

                                     = (6.022*10^23)*(0.031)

                                     =1.854*10^22 molecules.

Answer: 1.854*10^22 molecules

number of moles of Hg in compound = 0.031 mol

molar mass of Hg = 200.59gm

mass of Hg = number of moles * molar mass of Hg

                     =0.031*200.59

                    =6.22 gm

percentage of mercury = mass of mercury *100 / total mass

                                        = 6.22*100/7.1

                                        = 87.6 %

Answer: 87.6 %