Question

This is the balanced chemical equation for the combustion of methane gas: CH₄ + 2O₂ → CO₂ + 2H₂O. The subscript tells you how many atoms of a particular element are in a molecule. How many hydrogen atoms are in a molecule of methane (CH₄)?

1) 4
2) 1
3) 0
4) 8

Answer 1

A molecule of methane (CH₄) contains 4 hydrogen atoms. The correct answer to the question is 1) 4. The combustion of methane is an exothermic reaction releasing 890.4 kilojoules of heat.

Step-by-step explanation:

The balanced chemical equation for the combustion of methane gas is CH₄ + 2O₂ → CO₂ + 2H₂O. When we look closely at the molecular formula for methane (CH₄), we see that the subscript '4' following the capital letter 'H' indicates the number of hydrogen atoms present in a single molecule of methane. Thus, there are 4 hydrogen atoms in a molecule of methane. Referring to the multiple choice answers given, the correct answer to how many hydrogen atoms are in a molecule of methane is 1) 4.

The thermochemical equation for the combustion of methane shows not only the reactants and products but also includes the enthalpy change of the reaction. When 1 mol of methane combusts, it releases 890.4 kilojoules of heat. This is indicative of an exothermic reaction, where heat is released and therefore written as a product in the reaction.