Mixtures

A physical combination of two or more substances.

• Constituents retain their chemical properties
• Can be separated by physical methods

Types of Mixtures

1. Solid + Liquid mixture
   • Example: sugar in water, salt in oil
2. Liquid + Liquid mixture
   • Immiscible (do not mix): water + oil
   • Miscible (mix uniformly): water + alcohol
3. Solid + Solid mixture
   • Example: clay and sand, alloys
4. Solid + Gas mixture
   • Example: smoke, dust, foam mattress
5. Liquid + Gas mixture
   • Example: fog, mist, clouds
6. Gas + Gas mixture
   • Example: air

 

Classes of Mixtures

• Homogeneous mixture → uniform composition (e.g., salt + water, alcohol + water)
• Heterogeneous mixture → non-uniform composition (e.g., sand + water, oil + water)

Differences Between Homogeneous and Heterogeneous Mixtures

Homogeneous	Heterogeneous
Uniform mixture	Non-uniform mixture
Constituents cannot be seen	Constituents visible
Solute dissolves completely	Solute does not dissolve completely
One phase	Two or more phases
Stable over time	Constituents separate when undisturbed

Solute

A substance that dissolves in a solvent.

• Soluble: sugar, salt, ethanol
• Insoluble: sand, chalk, oil

Factors Affecting Dissolution

1. Smaller particle size → faster
2. Stirring → speeds mixing
3. Heating → increases rate

 

Solvent

The substance in which solutes dissolve.

• Usually present in larger quantity
• Water is called the universal solvent

Examples

Solvent	Solute
Water	Sugar, salt, milk powder
Turpentine	Oil paint
Petrol	Grease, fat, wax
Kerosene	Coal tar
Alcohol	Chlorophyll, dye
Soap	Fat
Benzene	Rubber

Differences Between Solvent and Solute

Solvent	Solute
Dissolves the solute	Dissolves in solvent
Larger quantity	Smaller quantity
Usually liquid or gas	Solid, liquid, or gas
Lower boiling point	Higher boiling point

Solution

A homogeneous mixture of two or more substances.

• Solute dissolves completely
• Constituents do not separate

Examples:

• Salt + water
• Sugar + water
• Vinegar + water
• Alcohol + water

Types of Solutions

• Dilute solution → less solute
• Concentrated solution → more solute but can still dissolve more
• Saturated solution → maximum solute dissolved

 

Suspension

A heterogeneous mixture where solute does not dissolve in the solvent.

• Particles visible to the naked eye
• Particles settle when undisturbed

Examples:

• Gari + water
• Muddy water
• Oil + water

Differences Between Solution and Suspension

Solution	Suspension
Homogeneous	Heterogeneous
Particles not visible	Particles visible
One phase	Two or more phases
Solute dissolves	Solute does not dissolve
Cannot be filtered	Can be filtered

Colloid

A mixture in which one substance is permanently dispersed in another medium.

• Stable, particles do not dissolve
• Too small to see with naked eye
• Appears homogeneous but is heterogeneous

Examples:

• Milk
• Starch in water
• Blood
• Egg
• Toothpaste

 

Differences Between Colloid and Suspension

Colloid	Suspension
Homogeneous in appearance	Heterogeneous
Particles do not settle	Particles settle