- What is the difference between an aqueous solution and a nonaqueous solution? Give one example of each.
Answer: A solution in which water is used as the solvent is called an aqueous solution. Example: Salt dissolved in water.
A solution prepared by dissolving a substance in a solvent other than water is called a nonaqueous solution. Example: Sulphur dissolved in carbon disulphide.
- Write any four characteristic properties of a true solution.
Answer:
- A true solution is a homogeneous mixture of solute and solvent.
- Solute particles are very small and cannot be seen with the naked eye.
- Solute particles do not settle down on standing.
- Solute particles cannot be separated by filtration.
- A true solution is transparent.
- A true solution does not scatter light.
3. What is a saturated solution and an unsaturated solution?
Answer: A saturated solution is a solution in which the maximum amount of solute has been dissolved at a particular temperature.
An unsaturated solution is a solution in which less than the maximum amount of solute is dissolved at a particular temperature.
4. What happens when a saturated solution is heated or cooled?
Answer: When a saturated solution is heated, it generally becomes unsaturated because more solute can dissolve in it.
When a saturated solution is cooled, crystallisation may occur and some dissolved solute separates out in the form of crystals.
5. Define solubility.
Answer: Solubility is the number of grams of a solute that can be dissolved in 100 grams of solvent at a specified temperature to make a saturated solution.
6. Name the factors that affect solubility.
Answer: The factors affecting solubility are:
Nature of solute
Nature of solvent
Temperature
Pressure
7. What is meant by the concentration of a solution?
Answer: The relative amount of solute and solvent present in a solution is called the concentration of the solution.
8. Write the formula for mass percentage of a solution.
Answer: mass percentage=Mass of solute/mass of solution ×100
Mass percentage is the number of parts by mass of solute dissolved in 100 parts by mass of the solution.
1. What is a suspension?
Answer: A suspension is a heterogeneous mixture in which solid particles having size greater than 1000 nm are distributed in a fluid without dissolving in it.
2. Write any four characteristic properties of a suspension.
Answer:
A suspension is a heterogeneous mixture.
The suspended particles can be seen with the naked eye or under a simple microscope.
The suspended particles settle down at the bottom on standing.
Suspended particles can be separated by filtration or decantation.
Suspended particles scatter light and make its path visible.
1. What is a colloid?
Answer: A colloid is a heterogeneous mixture in which one substance is dispersed as very fine particles of size 1 to 1000 nm in a continuous medium of another substance.
2. What are dispersed phase and dispersion medium?
Answer: The discontinuous phase of fine particles in a colloid is called the dispersed phase, while the continuous phase is called the dispersion medium.
3. Give any three examples of colloids.
Answer: Some common examples of colloids are milk, fog and smoke.
1. What is the Tyndall effect?
Answer: The scattering of light by colloidal particles, due to which the path of light becomes visible, is called the Tyndall effect.
2. Why can colloidal particles not be separated by ordinary filtration?
Answer: Colloidal particles are very small and can pass through ordinary filter paper. Therefore, they cannot be separated by simple filtration.
1. What is Brownian movement?
Answer: The continuous zig-zag random motion of colloidal particles in the dispersion medium is called Brownian movement.
2. What is coagulation of a colloid?
Answer: The process in which colloidal particles come together to form bigger particles and settle down as a precipitate is called coagulation.
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