Chemistry · Stoichiometry
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What is the weight of oxygen that required for the complete combustion of 3.2 kg of methane?
- A
3.2 kg
- B
6.4 kg
- C
12.8 kg
- D
15.4 kg
12.8 kg: This is the correct answer. Understanding the Chemical Reaction The complete combustion of methane (CH₄) with oxygen (O₂) produces carbon dioxide (CO₂) and water (H₂O). The balanced chemical equation is: CH₄ + 2O₂ → CO₂ + 2H₂O This equation tells us that 1 mole of methane reacts with 2 moles of oxygen.
Calculations
Molar Mass:
Methane (CH₄): (12.01 g/mol) + 4(1.008 g/mol) ≈ 16.04 g/mol
Oxygen (O₂): 2(16.00 g/mol) = 32.00 g/mol
Moles of Methane:
Convert the mass of methane to grams: 3.2 kg * 1000 g/kg = 3200 g
Calculate the moles of methane: 3200 g / 16.04 g/mol ≈ 199.5 moles
Moles of Oxygen:
From the balanced equation, 2 moles of oxygen are required for every 1 mole of methane.
Moles of oxygen: 199.5 moles * 2 = 399 moles
Mass of Oxygen:
Calculate the mass of oxygen: 399 moles * 32.00 g/mol = 12768 g
Convert grams to Kilograms: 12768g / 1000g/kg = 12.768 kg.
3.2 kg: This is incorrect. It's simply the mass of methane, and doesn't account for the stoichiometry of the reaction.
6.4 kg: This is incorrect. It represents double the mass of methane, but doesn't correctly apply the molar mass of oxygen or the 2:1 ratio from the balanced chemical equation.
12.8 kg: This is the correct answer. Understanding the Chemical Reaction The complete combustion of methane (CH₄) with oxygen (O₂) produces carbon dioxide (CO₂) and water (H₂O). The balanced chemical equation is: CH₄ + 2O₂ → CO₂ + 2H₂O This equation tells us that 1 mole of methane reacts with 2 moles of oxygen.
Calculations
Molar Mass:
Methane (CH₄): (12.01 g/mol) + 4(1.008 g/mol) ≈ 16.04 g/mol
Oxygen (O₂): 2(16.00 g/mol) = 32.00 g/mol
Moles of Methane:
Convert the mass of methane to grams: 3.2 kg * 1000 g/kg = 3200 g
Calculate the moles of methane: 3200 g / 16.04 g/mol ≈ 199.5 moles
Moles of Oxygen:
From the balanced equation, 2 moles of oxygen are required for every 1 mole of methane.
Moles of oxygen: 199.5 moles * 2 = 399 moles
Mass of Oxygen:
Calculate the mass of oxygen: 399 moles * 32.00 g/mol = 12768 g
Convert grams to Kilograms: 12768g / 1000g/kg = 12.768 kg.
15.4 kg: This is incorrect. It's a higher value than the calculated amount, and doesn't reflect the correct stoichiometric relationship.
Tagged under Chemistry · Stoichiometry · 2023