The Chemistry of Combustion: Calculating Oxygen Requirements

How much oxygen is needed to react completely with acetylene?

Considering the combustion reaction of acetylene (C2H2): 2C2H2 + 5O2 → 4CO2 + 2H2O, how many grams of oxygen would be required to react completely with 859.0 g C2H2?

Final answer:

To react completely with 859.0 g of acetylene, 2639 grams of oxygen gas are required, following the stoichiometric calculation based on the balanced chemical equation of the combustion reaction.

Explanation:

The combustion reaction of acetylene (C2H2) requires a certain amount of oxygen to react completely. Using the provided stoichiometric equation, 2C2H2 + 5O2 → 4CO2 + 2H2O, we can determine the mass of oxygen needed by first finding the molar mass of acetylene and oxygen, then using the molar ratio from the balanced equation.

First, calculate the molar mass of acetylene (C2H2):

  • Molar mass of C = 12.01 g/mol × 2 = 24.02 g/mol
  • Molar mass of H = 1.008 g/mol × 2 = 2.016 g/mol
  • Total molar mass of C2H2 = 24.02 g/mol + 2.016 g/mol = 26.036 g/mol

Next, calculate the moles of acetylene in 859.0 g:

  • 859.0 g C2H2 ÷ 26.036 g/mol = 32.987 moles of C2H2

Now, use the balanced equation to find the moles of oxygen gas needed:

  • According to the equation, 2 moles of C2H2 need 5 moles of O2. Thus, 32.987 moles of C2H2 will need 5/2 × 32.987 moles of O2 = 82.468 moles of O2

Finally, calculate the mass of O2 required:

  • Molar mass of O2 = 16.00 g/mol × 2 = 32.00 g/mol
  • Total mass of O2 = 82.468 moles × 32.00 g/mol = 2638.976 g of O2

Therefore, 2639 grams of oxygen would be required to react completely with 859.0 g C2H2.

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