CLASS - IX
Ch. 2 IS MATTER AROUND US PURE?
Mixture -
Composed of more than one substance
Substances retain their identity
Can be separated by physical processes (e.g. evaporation)
Examples: soft drink, soil
Solution -
- Homogeneous mixture of two or more substances
- Can be liquid, solid (alloys) or gas (air)
- Particles are evenly distributed throughout (homogeneous at particle level)
- Examples: lemonade, soda water, brass
Alloy -
- Mixture of metals (or metal and non-metal)
- Can't be separated by physical methods (but still considered a mixture)
- Shows properties of its components
- Has variable composition
- Example: brass (30% zinc, 70% copper)
Solution Components -
- Solvent: Dissolves other component (usually present in larger amount)
- Solute: Gets dissolved by solvent (usually present in lesser amount)
- Examples:
- Sugar solution (solid in liquid): sugar (solute), water (solvent)
- Tincture of iodine (solid in liquid): iodine (solute), alcohol (solvent)
- Soda water (gas in liquid): CO2 (solute), water (solvent)
- Air (gas in gas): homogeneous mixture, not a solution
Solution Properties:
- Homogeneous mixture
- Particle size < 1 nm (invisible)
- Doesn't scatter light (clear)
, - Not separable by filtration
- Stable (doesn't settle)
Concentration of a Solution:
- Amount of solute relative to solvent
- Concentration terms:
- Dilute: Less solute (compared to another solution)
- Concentrated: More solute (compared to another solution)
- Saturated: Maximum amount of solute dissolved at a given temperature
- Unsaturated: Less than the maximum amount of solute dissolved
- Solubility: Maximum amount of a solute that can dissolve in a solvent at a given temperature
- Concentration is calculated as:
- Amount of solute / Amount of solution (or solvent)
Concentration Units - Expressed in two ways:
1. Mass by mass percentage (%): (mass of solute / mass of solution) x 100
2. Mass by volume percentage (%): (mass of solute / volume of solution) x 100
Suspension - Heterogeneous mixture (unlike solutions)
- Solid particles are dispersed in a liquid
- Particles are large and visible to naked eye
- Particles don't dissolve but stay suspended
# Suspension Properties
* Mixture: Heterogeneous (uneven)
* Particle size: Large (visible to naked eye)
* Light scattering: Shows Tyndall effect (light path visible)
* Stability: Unstable, particles settle over time
* Separation: Filtration separates particles
# Colloidal Solution
* Mixture: Heterogeneous (uneven), but appears homogeneous due to small particle size
* Particle size: Smaller than suspension (not visible to naked eye)
Ch. 2 IS MATTER AROUND US PURE?
Mixture -
Composed of more than one substance
Substances retain their identity
Can be separated by physical processes (e.g. evaporation)
Examples: soft drink, soil
Solution -
- Homogeneous mixture of two or more substances
- Can be liquid, solid (alloys) or gas (air)
- Particles are evenly distributed throughout (homogeneous at particle level)
- Examples: lemonade, soda water, brass
Alloy -
- Mixture of metals (or metal and non-metal)
- Can't be separated by physical methods (but still considered a mixture)
- Shows properties of its components
- Has variable composition
- Example: brass (30% zinc, 70% copper)
Solution Components -
- Solvent: Dissolves other component (usually present in larger amount)
- Solute: Gets dissolved by solvent (usually present in lesser amount)
- Examples:
- Sugar solution (solid in liquid): sugar (solute), water (solvent)
- Tincture of iodine (solid in liquid): iodine (solute), alcohol (solvent)
- Soda water (gas in liquid): CO2 (solute), water (solvent)
- Air (gas in gas): homogeneous mixture, not a solution
Solution Properties:
- Homogeneous mixture
- Particle size < 1 nm (invisible)
- Doesn't scatter light (clear)
, - Not separable by filtration
- Stable (doesn't settle)
Concentration of a Solution:
- Amount of solute relative to solvent
- Concentration terms:
- Dilute: Less solute (compared to another solution)
- Concentrated: More solute (compared to another solution)
- Saturated: Maximum amount of solute dissolved at a given temperature
- Unsaturated: Less than the maximum amount of solute dissolved
- Solubility: Maximum amount of a solute that can dissolve in a solvent at a given temperature
- Concentration is calculated as:
- Amount of solute / Amount of solution (or solvent)
Concentration Units - Expressed in two ways:
1. Mass by mass percentage (%): (mass of solute / mass of solution) x 100
2. Mass by volume percentage (%): (mass of solute / volume of solution) x 100
Suspension - Heterogeneous mixture (unlike solutions)
- Solid particles are dispersed in a liquid
- Particles are large and visible to naked eye
- Particles don't dissolve but stay suspended
# Suspension Properties
* Mixture: Heterogeneous (uneven)
* Particle size: Large (visible to naked eye)
* Light scattering: Shows Tyndall effect (light path visible)
* Stability: Unstable, particles settle over time
* Separation: Filtration separates particles
# Colloidal Solution
* Mixture: Heterogeneous (uneven), but appears homogeneous due to small particle size
* Particle size: Smaller than suspension (not visible to naked eye)
