MediumChemistryHigh School (9–10)GeneralMixtures and Solutions › Separation of MixturesNumericalBoard Exam

Air has about 78 % nitrogen, 21 % oxygen and 1 % other gases by volume…

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Air has about $78\ \%$ nitrogen, $21\ \%$ oxygen and $1\ \%$ other gases by volume. How many litres of each are there in $750\ \text{L}$ of air?

Need a reminder? The key ideaShow

Distillation separates liquids that mix by their boiling points: the one with the lower boiling point boils off first and is condensed. Simple distillation needs boiling points more than about $25\ \text{K}$ apart; closer than that needs fractional distillation. Air is about $78\ \%$ nitrogen, $21\ \%$ oxygen and $1\ \%$ other gases by volume.

The worked solution

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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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