In the reaction of magnesium with oxygen, if 2 formula units of magnesium oxide are formed, how many \(\mathrm{O_2}\) molecules are needed to balance the equation?
Answer and explanation
Correct answer: One
The balanced equation is \(2\mathrm{Mg}+\mathrm{O_2}\rightarrow2\mathrm{MgO}\). \(2\mathrm{MgO}\) contains a total of 2 oxygen atoms, and one \(\mathrm{O_2}\) molecule also contains 2 oxygen atoms. Therefore, the coefficient of \(\mathrm{O_2}\) is 1. Choosing “two” would provide 4 oxygen atoms, so the equation would not be balanced.
Frequently asked questions
What is the correct answer to this question?
One
Why is this the correct answer?
The balanced equation is \(2\mathrm{Mg}+\mathrm{O_2}\rightarrow2\mathrm{MgO}\). \(2\mathrm{MgO}\) contains a total of 2 oxygen atoms, and one \(\mathrm{O_2}\) molecule also contains 2 oxygen atoms. Therefore, the coefficient of \(\mathrm{O_2}\) is 1. Choosing “two” would provide 4 oxygen atoms, so the equation would not be balanced.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
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