What is the formula mass of beryllium chloride, becl2?

To determine the formula mass of beryllium chloride, BeCl₂, we start up with the basis of one mole first.

Basis: 1 mole BeCl₂

To determine the molar mass of BeCl₂, we add up the mass of one mole of beryllium and two moles of chlorine.

1 mol Be = 9 g/mol

1 mol of Cl = 35.45 g/mol

Solving,

molar mass of BeCl₂ = (1 mol Be) (9 g/mol) + (2 mols Cl) (35.45 g/mol)

molar mass of BeCl₂ = 79.9 g

Then, we take into consideration that 1 mol is equal to 6.022 x 10²³ formula units.

formula mass BeCl₂ = (79.9 g/mol) (1 mol/6.022 x 10²³ formula units)

formula mass of BeCl₂ = 1.33 x 10⁻²² g/formula unit

Answer: 1.33 x 10⁻²² g/formula unit