krit.club logo

The Amazing World of Solutes, Solvents, and Solutions - Identifying Solutes and Solvents

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 particles smaller than 1 nm1\text{ nm} in diameter, which cannot be seen by the naked eye.

The Solute is the component of the solution that is dissolved in the solvent and is usually present in a lesser quantity.

The Solvent is the component of the solution that dissolves the other component and is usually present in a larger quantity.

Water (H2OH_2O) is often referred to as the 'Universal Solvent' because it can dissolve a wide variety of substances.

In a gaseous solution like Air, Nitrogen (N2N_2) is the solvent (approx. 78%78\%) and Oxygen (O2O_2) and other gases act as solutes.

Alloys are homogeneous mixtures of metals (or a metal and a non-metal) that cannot be separated into their components by physical methods. For example, Brass is a mixture of approximately 30%30\% Zinc (ZnZn) and 70%70\% Copper (CuCu).

A Saturated Solution is one in which no more solute can be dissolved at a specific temperature.

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

📐Formulae

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

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

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

Volume by volume percentage of a solution=Volume of soluteVolume of solution×100\text{Volume by volume percentage of a solution} = \frac{\text{Volume of solute}}{\text{Volume of solution}} \times 100

💡Examples

Problem 1:

Identify the solute and solvent in a solution of 'Tincture of Iodine'.

Solution:

Solute: Iodine (I2I_2); Solvent: Alcohol (Ethanol).

Explanation:

In Tincture of Iodine, solid iodine is dissolved in liquid alcohol. Since iodine is the substance being dissolved and is present in a smaller amount, it is the solute.

Problem 2:

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 percentage = 11.1%11.1\%

Explanation:

Mass of solute (NaClNaCl) = 40 g40\text{ g}. Mass of solvent (H2OH_2O) = 320 g320\text{ g}. Total mass of solution = 40+320=360 g40 + 320 = 360\text{ g}. Using the formula: 40360×100=11.1%\frac{40}{360} \times 100 = 11.1\%.

Problem 3:

Identify the solute and solvent in aerated drinks like soda water.

Solution:

Solute: Carbon dioxide (CO2CO_2); Solvent: Water (H2OH_2O).

Explanation:

Soda water contains gas dissolved in a liquid. The gas (CO2CO_2) is the solute and the liquid (H2OH_2O) is the solvent.

Identifying Solutes and Solvents - Revision Notes & Key Formulas | CBSE Class 8 Science