Chemistry 2007 JAMB Past Questions - Question 28: What is the volume of oxygen required to burn completely 45 cm³ of methane at s.t.p.?

Correct Answer

D

Explanation

The balanced equation for the complete combustion of methane is:

CH₄ + 2O₂ → CO₂ + 2H₂O

This equation tells us that 1 volume of methane reacts with 2 volumes of oxygen to produce 1 volume of carbon dioxide and 2 volumes of water vapor. Since we are assuming standard temperature and pressure (STP), we can treat the volumes of gases as if they were directly proportional to their amounts.

Therefore, to burn completely 45 cm³ of methane, we need:

**Volume of oxygen = (2 volumes of O₂ / 1 volume of CH₄) * 45 cm³ of CH₄ = 90 cm³ of O₂**

So, 90 cm³ of oxygen is required to burn completely 45 cm³ of methane at STP.