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Phosphine (PH₃) is used as an insecticide in the storage of grain - Scottish Highers Chemistry - Question 3 - 2016
Question 3
Phosphine (PH₃) is used as an insecticide in the storage of grain. Phosphine can be produced by the reaction of water with aluminium phosphide: AlP(s) + 3H₂O(l) ⟶ P... show full transcript
Worked Solution & Example Answer:Phosphine (PH₃) is used as an insecticide in the storage of grain - Scottish Highers Chemistry - Question 3 - 2016
Step 1
State the type of bonding and structure in phosphine.
Answer
Phosphine (PH₃) exhibits covalent molecular bonding. In this molecule, phosphorus is covalently bonded to three hydrogen atoms, forming a trigonal pyramidal shape due to the presence of a lone pair of electrons on the phosphorus atom.
Step 2
Calculate the volume of phosphine gas, in litres, that would have been produced.
Answer
To find the volume of phosphine gas produced from 2.9 kg of aluminium phosphide, we first calculate the number of moles of AlP:
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Calculate the molar mass of AlP:
- Al: 27 g/mol
- P: 31 g/mol
- Molar mass of AlP = 27 + 31 = 58 g/mol
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Calculate the number of moles of AlP in 2.9 kg:
- Mass = 2900 g
- Moles of AlP = mass/molar mass = 2900 g / 58 g/mol = 50 moles.
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From the reaction, 1 mole of AlP produces 1 mole of PH₃:
- Therefore, moles of PH₃ = 50 moles.
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Calculate the volume of PH₃ produced:
- Volume = moles × volume of 1 mole = 50 × 24 litres = 1200 litres.
Thus, the volume of phosphine gas produced is 1200 litres.
Step 3