Avogadro's number is equal to 6.022 x 10^23 molecules/mol, which represents the number of particles (molecules, atoms, ions, etc.) present in one mole of a substance.
The molar mass of dimethylmercury (CH₃HgCH₃) can be calculated by adding the atomic masses of each atom in the molecule:
Molar mass of dimethylmercury = (2 x atomic mass of C) + (2 x atomic mass of H) + (2 x atomic mass of Hg)
Molar mass of dimethylmercury = (2 x 12.01 g/mol) + (2 x 1.008 g/mol) + (2 x 200.59 g/mol)
Molar mass of dimethylmercury ≈ 406.62 g/mol
Now, we can calculate the number of moles in a 5.00 g sample of dimethylmercury using the formula:
Number of moles = mass of sample / molar mass
Number of moles = 5.00 g / 406.62 g/mol
Number of moles ≈ 0.0123 mol
Finally, we can calculate the number of molecules in 0.0123 mol of dimethylmercury using Avogadro's number:
Number of molecules = Number of moles x Avogadro's number
Number of molecules ≈ 0.0123 mol x 6.022 x 10^23 molecules/mol
Number of molecules ≈ 7.43 x 10^21 molecules
Therefore, there are approximately 7.43 x 10^21 molecules in a 5.00 g sample of dimethylmercury.
