During the electrolysis of water, if the volume of hydrogen collected is 18 mL at the same temperature and pressure, what is the expected volume of oxygen?
Answer and explanation
Correct answer: 9 mL
The balanced equation is \(2\mathrm{H_2O}\rightarrow 2\mathrm{H_2}+\mathrm{O_2}\). At the same temperature and pressure, gas volumes are proportional to their moles, so \(\mathrm{H_2}:\mathrm{O_2}=2:1\). Therefore, for 18 mL of hydrogen, the oxygen volume is \(18\div2=9\) mL. The 18 mL option is incorrect because the two gases are not produced in equal volumes.
Frequently asked questions
What is the correct answer to this question?
9 mL
Why is this the correct answer?
The balanced equation is \(2\mathrm{H_2O}\rightarrow 2\mathrm{H_2}+\mathrm{O_2}\). At the same temperature and pressure, gas volumes are proportional to their moles, so \(\mathrm{H_2}:\mathrm{O_2}=2:1\). Therefore, for 18 mL of hydrogen, the oxygen volume is \(18\div2=9\) mL. The 18 mL option is incorrect because the two gases are not produced in equal volumes.
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.
