Is Matter Around Us Pure?

Chapter

Is Matter Around Us Pure?

Subject

Science - Class 9

Presented by

[Your Name / ALES INSTITUTIONS]

Introduction to Matter

Pure Substance

Made up of only one kind of particle.

Impure Substance

Made up of two or more kinds of particles.

Types of Matter

Pure Substances

Elements and Compounds

Mixtures

Homogeneous and Heterogeneous

What is a Pure Substance?

Definition

A substance made of only one kind of particles.

Composition

Fixed composition.

Properties

Uniform properties.

Examples

Water (H₂O), Oxygen (O₂), Gold (Au)

Types of Pure Substances

Elements

Cannot be broken down into simpler substances. Examples: Iron (Fe), Hydrogen (H₂), Oxygen (O₂)

Compounds

Made of two or more elements in a fixed ratio, can be broken down by chemical methods. Examples: Water (H₂O), Carbon dioxide (CO₂)

What is a Mixture?

Combination of Substances

A mixture involves two or more substances joined together.

Not Chemically Combined

Components maintain their individual properties in a mixture.

Physical Separation

Mixtures can be separated using physical methods like filtering or evaporation.

Variable Composition

The proportions of components in a mixture can change.

Types of Mixtures

Homogeneous Mixture

Uniform composition

Heterogeneous Mixture

Non-uniform composition

Examples

Sugar in water, Oil and water

Difference Between Mixtures and Compounds

Property

Mixture

Compound

Composition

Variable

Fixed

Separation

Physical methods

Chemical methods

Properties

Retain original properties

New properties formed

Formula

No definite formula

Definite chemical formula

Solutions

Homogeneous mixture

Two or more substances combined evenly.

Example

Salt in water is a common example.

Components

Solute

Substances being dissolved (e.g., salt).

Solvent

Substance in which solute dissolves (e.g., water).

Properties of a Solution

Homogeneous

Clear and Transparent

Cannot be Separated by Filtration

Stable

Particles do not settle.

Concentration of Solution

Dilute Solution

Less solute

Concentrated Solution

More solute

Formula for Concentration

Concentration = (Mass of solute / Mass of solution) × 100

Types of Solutions

Solid in Liquid

e.g., Sugar in water

Gas in Liquid

e.g., CO₂ in soda

Liquid in Liquid

e.g., Alcohol in water

Gas in Gas

e.g., Air – mixture of gases

Suspensions

Heterogeneous mixture

Solute particles do not dissolve

Particles are visible

Can be separated by filtration

Example: Mud in water

Colloids

Particle Size

Mixture where particles are intermediate in size

Homogeneity

Looks homogeneous but is actually heterogeneous

Tyndall Effect

Scattering of light is visible

Examples

Examples include Milk, Fog, Blood

Differences: Solution, Suspension & Colloid

Property

Solution

Suspension

Colloid

Visibility

Invisible

Visible

Invisible

Filtration

Not possible

Possible

Not possible

Tyndall Effect

No

Yes (if dense)

Yes

Particle Size

Small

Large

Medium

Stability

Stable

Unstable

Stable

Separation of Mixtures(1)

Handpicking

Filtration

Evaporation

Centrifugation

Sublimation

Distillation

Separation of Mixtures(2)

Chromatography

Magnetic separation

Applications of Separation Techniques

Evaporation

Salt from sea water

Distillation

Pure water from salty water

Centrifugation

Cream from milk

Chromatography

Ink separation

Activity-Based Learning

Tyndall Effect Demonstration

Ink Separation using Chromatography Paper

Salt from Saltwater by Evaporation

Summary of Matter

Pure Matter

Elements and compounds are types of pure matter.

Mixtures

Mixtures can either be homogeneous or heterogeneous.

Types of Mixtures

Solutions, suspensions, and colloids are different mixture types.

Separation Methods

Various physical methods can be used to separate components.

Important Questions in Chemistry

What is a pure substance?

A pure substance is a material consisting of only one type of particle.

Element and Compound

An element is a pure substance made of only one kind of atom, e.g., oxygen. A compound consists of two or more elements chemically combined, e.g., water.

Homogeneous vs. Heterogeneous Mixtures

Homogeneous mixtures have a uniform composition, while heterogeneous mixtures contain distinct regions.

The Tyndall Effect

The Tyndall effect is the scattering of light by particles in a mixture, observed in colloids.

Solution vs. Suspension

Solutions are homogeneous and transparent, while suspensions are heterogeneous and can settle over time.

Separation Techniques

Filtration and distillation are common methods for separating mixtures based on physical properties.

HOTS Questions

Air as a Homogeneous Mixture

Why is air considered a homogeneous mixture?

Milk as a Colloid

Milk is a colloid. Justify.

Separation of Mixtures

How would you separate a mixture of salt, sand, and iron?

Water as a Compound

Why is water considered a compound and not a mixture?

Quiz Time / MCQs

Homogeneous Mixture

Which of the following is a homogeneous mixture? (b) Salt in water ✅

Tyndall Effect

Tyndall effect is not shown by: (a) True solution ✅

Thank You!

Purity in Science

Brings clarity in understanding!

ALES INSTITUTIONS

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