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Which compound needs the greatest amount of oxygen for the complete combustion of 1 mol of the compound? A - AQA - A-Level Chemistry - Question 25 - 2021 - Paper 3
Question 25
Which compound needs the greatest amount of oxygen for the complete combustion of 1 mol of the compound? A. ethanal B. ethanol C. ethane-1,2-diol D. methanol
Worked Solution & Example Answer:Which compound needs the greatest amount of oxygen for the complete combustion of 1 mol of the compound? A - AQA - A-Level Chemistry - Question 25 - 2021 - Paper 3
Step 1
Step 2
Write the Complete Combustion Reactions
Answer
-
Ethanal:
C2H4O + 3 O2 → 2 CO2 + 2 H2O
Needs 3 moles of O2. -
Ethanol:
C2H5OH + 3 O2 → 2 CO2 + 3 H2O
Needs 3 moles of O2. -
Ethane-1,2-diol:
C2H6O2 + 3 O2 → 2 CO2 + 3 H2O
Needs 3 moles of O2. -
Methanol:
CH3OH + 1.5 O2 → CO2 + 2 H2O
Needs 1.5 moles of O2.
Step 3
Determine the Compound with the Greatest Oxygen Requirement
Answer
From the reactions, we can see that ethanal, ethanol, and ethane-1,2-diol each require 3 moles of O2, whereas methanol only requires 1.5 moles. Thus, the compounds needing the greatest amount of oxygen are ethanal, ethanol, and ethane-1,2-diol. However, since the question asks for one compound, ethanol is correctly identified as the one needing 3 moles of oxygen.
Step 4