An illustration shows several molecules in a space. There are five different types. There is one molecule with one O and two Hs. This is labeled water (H2O) traces. Another molecule has two Os and is labeled oxygen (O2) 21%. Another molecule has one C and two Os. This is labeled carbon dioxide (CO2) 0.04%. Another molecule has two Ns and is labeled nitrogen (N2) 78%. Another molecule has one Ar and is labeled argon (Ar) 0.9%.

Question

The image depicts the composition of air. Use the image to explain why this statement is correct: “Mixtures are composed of different proportions of pure substances.” 5 grade words

Answer 1

The image shows us that air is made up of different kinds of gases, which are all pure substances. For example, water (H2O) is made of hydrogen and oxygen, while oxygen (O2) is made up of only oxygen atoms. Each gas is unique and stands alone as a pure substance.

When we look at the atmosphere, we can see that it has different gases mixed together in different amounts. For instance, nitrogen (N2) makes up 78% of the air, while oxygen (O2) is 21%, and argon (Ar) is 0.9%. Carbon dioxide (CO2) is present in an even smaller amount at 0.04%.

This tells us that mixtures, like the air we breathe, are formed by blending these different pure substances in varying proportions or amounts. So, we can say “Mixtures are composed of different proportions of pure substances” because air includes many gases, each with its own amount!