Phosphine (PH₃) is used as an insecticide in the storage of grain - Scottish Highers Chemistry - Question 3 - 2016

To determine the volume of phosphine gas produced from 2.9 kg of aluminium phosphide, we first convert the mass to moles:

1. Calculate the molar mass of AlP: Molar mass of Al = 27 g/mol, Molar mass of P = 31 g/mol, thus Molar mass of AlP = 58 g/mol.

2. Convert 2.9 kg to grams: 2.9 kg = 2900 g.

3. Calculate moles of AlP:

   $n = \frac{mass\ (g)}{molar\ mass\ (g/mol)} = \frac{2900}{58} = 50\ moles$

4. From the balanced equation, 1 mole of AlP produces 1 mole of PH₃. Thus, moles of PH₃ produced = 50 moles.

5. Calculate the volume:

   $Volume\ (litres) = n \times Volume\ of\ 1\ mole\ (litres) = 50 \times 24 = 1200\ litres$

The structural formula for diphosphane (P₂H₄) is depicted as:

   H   H
    \ /
     P - P
    / \
   H   H

This shows the bonding between the two phosphorus atoms and the hydrogen atoms.