Question

In an experiment, a 60 cm3 sample of biogas required 80 cm3 of oxygen for the complete combustion of the methane in the sample. Calculate the percentage of methane in the sample of biogas. Assume that biogas contains only methane and carbon dioxide.

CH4 + 2O2 → CO2 + 2H2O

Answer 1

To calculate the percentage of methane in the sample of biogas, you can use the stoichiometry of the reaction to determine the amount of methane that reacted with oxygen. The balanced equation tells us that one molecule of methane reacts with two molecules of oxygen.

Given that the biogas sample required 80 cm³ of oxygen for complete combustion, this means that half that volume, or 40 cm³, reacted with methane.

Now, to find the percentage of methane in the biogas sample, divide the volume of methane (40 cm³) by the initial volume of the biogas sample (60 cm³) and then multiply by 100 to get the percentage:

Percentage of methane = (Volume of methane / Initial volume of biogas) * 100

Percentage of methane = (40 cm³ / 60 cm³) * 100

Percentage of methane = 66.67%

So, the percentage of methane in the sample of biogas is approximately 66.67%.

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