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Year 5 Science

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Solutions

You may have noticed that oil and water donít mix very well. Try pouring a little oil and water into a bottle and shaking it. You will see that they separate again when you put the bottle down. One way of explaining this is to say that water molecules stick to each other really well, but they donít stick to oil molecules very well.

But what if you put a spoonful of sugar into a glass of warm water and stir it up? If you stir long enough, the sugar seems to disappear. Unlike oil, sugar molecules blend well with water molecules. Sugar is one of a certain kind of molecule that attracts water molecules well, pulls them apart and manages to mingle in between those water molecules.

atoms

When this happens, we say the sugar has dissolved in water. We call the water the solvent and the sugar the solute. The sugar is still there, even though you canít see it!

Of course, you canít go on adding sugar to the solution forever. A solvent (in this case water) can only dissolve a certain amount of a solute (in this case sugar). When the maximum amount of a solute is dissolved in a solvent, we say that the solution is saturated .


This activity is adapted from page 304 of What Your Year 5 Child Needs to Know, which can be purchased here.