Concentrated, dilute and saturated solutions Imagine how a cup of tea would taste if you put 10 teaspoons of sugar in it. Would it taste the same as a cup of tea with just one teaspoon of sugar? Solutions with large amounts of solute in them are called concentrated solutions. Solutions with small amounts of solute in them are called dilute solutions. To make a solution more concentrated you either have to add more solute or reduce the amount of solvent. To make a solution more dilute you add more solvent. What would happen if more and more sugar was added to a cup of tea? Try the activity below to find out.
Activity How much solute can dissolve?
Apparatus Beaker, spatula, sugar, water
Method 1. Put 20 cm3
of water in a small beaker.
2. Add a small amount of sugar to it and stir. 3. Repeat step 2 until you observe a change.
Questions 1. Did the solution become more dilute or concentrated as more sugar was added? 2. What change did you observe? 3. Can you think of a reason why this happened?
A saturated
It is likely that after a few spatulas of sugar are added, no more sugar will dissolve. Instead the sugar will start to settle at the bottom of the beaker. This happens because all the spaces between the water molecules have been filled by sugar and no more sugar can fit. We call solutions in which no more solute will dissolve saturated solutions. Solubility is a property of materials that you will study in Chapter 21. It is calculated as the number of grams of a solute that will dissolve in 100 cm3
of solvent.
Solute that does not dissolve falls to the bottom.
Fig. 4 Dilute, concentrated and saturated solutions of copper sulfate. Dilute
Solution
Concentrated Solution
20.2 Separating mixtures
Mixtures form without any chemical changes taking place. Because of this it is possible to separate them into the different materials that make them up.
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Saturated Solution
solution is one in which no more solute will dissolve.
Solubility is a measure of the ability of a substance to
dissolve in another substance.
A concentrated
solution contains a lot of solute in a little solvent.
A dilute solution contains a little solute in a lot of solvent.
