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Factors affecting Solubility

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A solution is a liquid that is a homogeneous combination of one or more solutes and a solvent. A frequent example of a solution is sugar cubes added to a cup of tea or coffee. Solubility is the characteristic that allows sugar molecules to dissolve. As a result, the term solubility may be defined as a substance’s (solute’s) ability to dissolve in a particular solvent. A solute is any material that may be solid, liquid, or gas when dissolved in a solvent.

Physical Changes

When the composition of a substance remains unchanged despite its molecules being rearranged, it is called a physical change. Physical change is a temporary change. e.g. melting of ice, etc.

Properties of Physical Changes

  1. It is a temporary change.
  2. It only affects the physical properties of the substance i.e. shape, size, etc.
  3. It involves very little to no absorption of energy.
  4. Usually, physical changes do not involve the production of energy.
  5. No new substance is formed.
  6. Physical change is easily reversible i.e original substance can be recovered.

Chemical Change

When the molecular composition of a substance is changed entirely, it is called a chemical change. Thus, chemical changes involve the formation of new substances. A chemical change is a permanent change. e.g. the digestion of food etc.

Properties of Chemical Changes

  1. It is a permanent change.
  2. It can change both the physical and chemical properties of the substance including its composition
  3. Absorption and the evolution of energy take place.
  4. It usually involves the production of energy.
  5. It is always accompanied by one or more new substance(s).
  6. It is irreversible i.e. original substance cannot be recovered.

Solute: Solute is the substance that dissolves in a solvent to produce a homogeneous mixture.

Solvent: Solvent is the substance in which a solute dissolves to produce a homogeneous mixture.

Solute and solvent both can be gas, liquid or solid. For example, in a salt and water solution, salt is solute and water is solvent.

Solubility and Solubility Product

Solubility is the maximum amount of solute that can be dissolved in a certain quantity of solvent at a certain temperature. The factors affecting solubility depends on the state of solute and can be classified into the following are:

  1. Liquids In Liquids
  2. Solids In Liquids
  3. Gases In Liquids

Solubility product is the maximum product of the molar concentration of the ions produced due to dissociation of the compound. At a given temperature the solubility product is constant. A low solubility product indicates lower solubility and vice versa.

1. Solubility of Liquid in liquid

Depending on the concentration of solute dissolved in a solvent, solutes are classified into highly soluble, sparingly soluble or insoluble. If more than 0.1 g solute can be dissolved in a 100 ml solvent, it is called soluble. If it is less than 0.1 g, it is called sparingly soluble. A solution in which a particular amount of solute is completely soluble in a solvent at a given temperature is called a saturated solution while a solution where solute starts precipitating at a particular concentration at the same temperature is called a supersaturated solution. Factors affecting solubility are-

  • Temperature- Solubility increases with temperature in the case of solid and liquid while in the case of gases, it decreases with an increase in temperature.
  • Forces- It varies according to the type of intermolecular forces and bonds. Thus, like dissolves like and dissolving of unlike substances is challenging.
  • Pressure- With the increase in partial pressure in gases, solubility increases.

2. Solubility of solids in liquid

When a solid solute is added to a solvent, solute particles dissolve in it by the process of dissolution. Solute particles in solution collide with one other which separates some of the particles from the solution. This process is called crystallization. A state of dynamic equilibrium is established between these two processes and at this point, the number of solute molecules entering the solution becomes equal to the number of particles leaving the solution which makes the concentration of the solute in the solution constant at a given temperature and pressure. Factors Affecting Solubility are-

  • Effect of Temperature- Solubility increases with an increase in temperature if the dissolution process is endothermic, it decreases with an increase in temperature if the process is exothermic.
  • Effect of Pressure- It is not affected much by a change in pressure.

3. Solubility of gases in liquid

This concept deals with gas dissolving in a solvent. Gas solubility in liquids is greatly affected by temperature and pressure as well as the nature of the solute and the solvent.

  • Pressure- Solubility increases with an increase in pressure. Henry’s Law gives a quantitative relation between pressure and gas solubility in a liquid. It states that The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution.
  • Temperature- Solubility decreases with an increase in temperature. Gaseous molecules are dissolved by dissolution and in this process, heat is evolved. According to Le Chatelier’s Principle, the equilibrium of a system is disturbed, the system readjusts itself in such a way that the effect that has caused the change in equilibrium is countered.  As dissolution is an exothermic process, the solubility should decrease with an increase in temperature to validate Le Chatelier’s Principle.

Sample Questions

Question 1: Explain the solubility of solids in liquid?

Answer: 

When solid solute is added to a solvent, solute particles dissolve in it by the process of dissolution. Solute particles in solution collide with one other which separates some of the particles from the solution. This is called crystallization. Factors Affecting Solubility are temperature and pressure.

Question 2: Define solubility and classify it.

Answer: 

Solubility is defined as the maximum amount of solute that can be dissolved in a certain quantity of solvent at a certain temperature. The factors affecting solubility depends on the state of solute and can be classified into liquids In liquids , solids In liquids and gases In liquids

Question 3: Define Le Chatelier’s Principle.

Answer: 

According to Le Chatelier’s Principle, the equilibrium of a system is disturbed, the system readjusts itself in such way that the effect that has caused the change in equilibrium is countered

Question 4: Define solubility product.

Answer: 

Solubility product is the maximum product of the molar concentration of the ions produced due to dissociation of the compound. At a given temperature the solubility product is constant. Low solubility product indicates lower solubility and vice versa.

Question 5: Define Henry Law. 

Answer: 

Henry’s Law gives a quantitative relation between pressure and gas solubility in a liquid. It states that The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution.

Question 6: Define dissolution and crystallization.

Answer: 

When solid solute is added to a solvent, solute particles dissolve in it by the process of dissolution. Solute particles in solution collide with one other which separates some of the particles from the solution. This process is called crystallization.

Question 7: Does temperature affect solubility?

Answer: 

The solubility increases with temperature for solids that can be dissolved in water. The rise in higher temperature helps the solvent molecules to break apart the solute molecules that are kept together by intermolecular attractions more effectively.


Last Updated : 16 Sep, 2021
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