Question

Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it, should you add ice to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?

Answer 1

We will use solubility and temperature relations to decide when we should add the sugar. Solubility and temperature are directly proportional. As temperature solubility increases. On decreasing temperature means cooling solubility decreases.

Complete answer :
The solubility is defined as the amount of solute dissolved in a given amount of solvent to give a saturated solution.

The effect of temperature on the solubility is as follows:
At an increasing temperature, the kinetic energy of the particles increases, so the bonds of the solute particles break and the solute easily dissolves so, on increasing temperature the solubility increases.

The effect of the addition of ice on the solubility is as follows:
On the addition of the ice, the temperature of the solution decreases so the solubility of the solute decreases.

So, if we add the sugar in the saturated lemonade after the addition of ice, the extra sugar will not dissolve. So, we will add the sugar before the addition of ice because lemonade will be at room temperature, so it will dissolve the extra added sugar. Then we will add the ice to cool it.
If you wish to add ice to cool lemonade, you should add ice to the lemonade after dissolving sugar. In the case of hot lemonade, it is possible to dissolve more sugar.

Note: In the case of a saturated solution, on increasing the temperature it is possible to dissolve more solute. In the case of an unsaturated solution, it is possible to dissolve solute to make it saturated without increasing the temperature. A saturated solution is a solution in which the addition of more solute is not possible.