EasyChemistryHigh School (9–10)GeneralMixtures and Solutions › Mixtures, Solutions and ColloidsConceptualBoard Exam
Name the main gases in air. Is air a homogeneous or a heterogeneous mixture? …
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
- Name the main gases in air. Is air a homogeneous or a heterogeneous mixture? Why?
- Air is oxygen by volume. How many litres of oxygen are there in of air? (.)
Need a reminder? The key ideaShow
A pure substance has one kind of matter and fixed properties, such as a sharp melting point. A mixture has two or more substances in any amounts; each keeps its own properties. A homogeneous mixture (a solution, an alloy, air) is the same all through; a heterogeneous one is not.
The worked solution
Have you tried it?
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.
Step 1. (a) Nitrogen (about ), oxygen (about ), and small amounts of argon, carbon dioxide and water vapour. Air is homogeneous: the gases are spread evenly, and no separate parts can be seen.
Step 2. (b) , so oxygen is .
Answer: (a) Mostly nitrogen and oxygen; homogeneous. (b) of oxygen.
Check. Air is still a mixture, not a compound: its make-up can vary a little, for example with more water vapour on a humid day.
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