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The Amazing World of Solutes, Solvents, and Solutions - Effect of Temperature on Solubility

Grade 6CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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A Solution is a homogeneous mixture formed when a Solute (the substance that dissolves) is mixed with a Solvent (the substance that does the dissolving, like H2OH_2O).

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Solubility is defined as the maximum amount of solute that can be dissolved in a specific volume of solvent at a constant temperature.

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A Saturated Solution is a solution in which no more solute can be dissolved at a given temperature. Any additional solute added will settle at the bottom.

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The Effect of Temperature: For most solid solutes, solubility increases as the temperature of the solvent increases. This is because heating provides more energy to break the bonds between solute particles and creates more space between solvent molecules.

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When a saturated solution is cooled, its solubility decreases. This often leads to the process of Crystallization, where the excess dissolved solute separates from the solution as crystals.

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An Unsaturated Solution is a solution that contains less than the maximum amount of solute that can be dissolved at a specific temperature. Heating a saturated solution usually turns it into an unsaturated one.

📐Formulae

Solute+Solvent=Solution\text{Solute} + \text{Solvent} = \text{Solution}

Solubility=Mass of Solute (g)Mass of Solvent (g)×100\text{Solubility} = \frac{\text{Mass of Solute (g)}}{\text{Mass of Solvent (g)}} \times 100

Temperature∝Solubility (for most solids)\text{Temperature} \propto \text{Solubility (for most solids)}

💡Examples

Problem 1:

Rohan prepared a saturated solution of sugar in 100100 mL of water at 25∘C25^\circ C. He then heated the solution to 50∘C50^\circ C. Will the solution remain saturated? What will happen if he adds more sugar?

Solution:

The solution will become Unsaturated upon heating. He will be able to dissolve more sugar into the water at 50∘C50^\circ C.

Explanation:

Increasing the temperature from 25∘C25^\circ C to 50∘C50^\circ C increases the solubility of sugar in H2OH_2O. The extra thermal energy allows more sugar molecules to fit between the water molecules.

Problem 2:

A hot saturated solution of Copper Sulphate (CuSO4CuSO_4) is allowed to cool down to room temperature. What observation will be made?

Solution:

Blue crystals of Copper Sulphate (CuSO4CuSO_4) will start to appear at the bottom of the container.

Explanation:

Solubility of CuSO4CuSO_4 decreases as the temperature drops. Since the cold water cannot hold as much solute as the hot water, the excess CuSO4CuSO_4 precipitates out of the solution as crystals.