Question

Two chemist are trying to determine if their water sample is a mixture or pure substance. In their investigation they first filter the sample of dirty water with gravel. The water is then clearer then before. See image. What does this change tell the chemist about the chemical make up of the sample

The dirty water is only a mixture because it was not completely filtered by the gravel.


Dirty water is a mixture of solid particles and liquid. It is both a mixture and pure substance.


More information is needed to answer the question.


The dirty water is only a pure substance now that it has been filtered by the gravel

Answer 1

The correct answer is option B. Dirty water is a mixture of solid particles and liquid. It is both a mixture and pure substance.

The dirty water sample has both gravel and liquid water in it. After filtration the gravel is removed so the water sample looks clearer than before filtration. Liquid water is a pure substance because it is a compound that is made up of elements hydrogen and oxygen. Now the gravel is only physically combined with the liquid water, thus giving the water sample properties of a mixture. And like any mixture, gravel is physically separated through filtration from the liquid water.

Thus the water sample of the chemists is both a mixture and pure substance.