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The Amazing World of Solutes, Solvents, and Solutions - Types of Solutions and Their Properties

Grade 8CBSE

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

🔑Concepts

A solution is a homogeneous mixture of two or more substances. It consists of a solute (the substance being dissolved) and a solvent (the substance doing the dissolving), such as NaClNaCl in H2OH_2O.

The particles of a solution are smaller than 1 nm1\text{ nm} (109 m10^{-9}\text{ m}) in diameter, which is why they cannot be seen by the naked eye.

Solutions do not scatter a beam of light passing through them because of their very small particle size; hence, they do not show the Tyndall effect.

A saturated solution is one in which no more solute can be dissolved at a specific temperature. Any solution containing less than the maximum amount of solute is called an unsaturated solution.

Solubility is the maximum amount of solute that can be dissolved in a given amount of solvent at a specific temperature.

The concentration of a solution is the amount of solute present in a given quantity of the solution, often expressed as a percentage by mass or volume.

📐Formulae

Mass of solution=Mass of solute+Mass of solvent\text{Mass of solution} = \text{Mass of solute} + \text{Mass of solvent}

Mass by mass percentage of a solution=(Mass of soluteMass of solution)×100\text{Mass by mass percentage of a solution} = \left( \frac{\text{Mass of solute}}{\text{Mass of solution}} \right) \times 100

Mass by volume percentage of a solution=(Mass of soluteVolume of solution)×100\text{Mass by volume percentage of a solution} = \left( \frac{\text{Mass of solute}}{\text{Volume of solution}} \right) \times 100

💡Examples

Problem 1:

A solution contains 40 g40\text{ g} of common salt (NaClNaCl) in 320 g320\text{ g} of water (H2OH_2O). Calculate the concentration in terms of mass by mass percentage of the solution.

Solution:

Mass of solute (NaClNaCl) = 40 g40\text{ g}. Mass of solvent (H2OH_2O) = 320 g320\text{ g}. Mass of solution = 40 g+320 g=360 g40\text{ g} + 320\text{ g} = 360\text{ g}. Using the formula: Concentration=(40/360)×100=11.1%\text{Concentration} = (40 / 360) \times 100 = 11.1\%.

Explanation:

To find the mass by mass percentage, we first determine the total mass of the solution by adding the mass of the solute and the solvent, then divide the solute mass by this total and multiply by 100.

Problem 2:

What happens to the solubility of a solid solute in a liquid solvent like H2OH_2O when the temperature is increased?

Solution:

The solubility generally increases with an increase in temperature.

Explanation:

As temperature increases, the kinetic energy of the solvent molecules increases, allowing them to break the intermolecular forces of the solute more effectively, thus dissolving more solute.