Calculate the molecular masses of the following compounds:

• (a) Hydrogen sulphide, H₂S
• (b) Carbon disulphide, CS₂

(Atomic masses: H = 1u, S = 32u, C = 12u)

To calculate the molecular masses of the given compounds, we will sum the atomic masses of all the atoms in each molecule.

Molecular Mass of Hydrogen Sulphide (H₂S)

Hydrogen sulphide consists of two hydrogen atoms and one sulphur atom. The calculation is as follows:

• Hydrogen: 2 atoms × 1 u = 2 u
• Sulphur: 1 atom × 32 u = 32 u

Adding these together gives:

Total molecular mass of H₂S = 2 u + 32 u = 34 u

Molecular Mass of Carbon Disulphide (CS₂)

Carbon disulphide contains one carbon atom and two sulphur atoms. The calculation is as follows:

• Carbon: 1 atom × 12 u = 12 u
• Sulphur: 2 atoms × 32 u = 64 u

Adding these together gives:

Total molecular mass of CS₂ = 12 u + 64 u = 76 u

In summary, the molecular masses are:

• H₂S: 34 u
• CS₂: 76 u