Is Matter Around Us Pure-Notes
Class IX Science
Notes for Is matter Around Us Pure
Notes for Is matter Around Us Pure
Facts that Matter
• Compounds
Compound is a pure substance made up of two or more elements combined chemically in a definite ratio.
Characteristics:
1. The properties of compound differ from those of its constituents.
2. Compound has fixed melting point and boiling point.
3. Compound is a homogeneous substance.
4. Constituent elements can be separated by chemical process.
• Mixtures
It is made up of two or more elements or compounds mixed in any ratio/proportion.
Properties:
• It may be homogeneous of heterogeneous.
• The properties of constituent substances are retained.
• No new compound is formed.
• Elements can be separated by simple physical processes.
• It does not have fixed melting and boiling point.
Separation of Mixtures:
| Type of Mixture | Separation method |
| 1. Two immiscible liquids. Example, oil + water | By using separating funnel |
| 2. Ammonium chloride + sand | Sublimation |
| 3. Dyes in black ink. (One solvent different constituents) | Chromatography |
| 4. Two miscible liquids. (Acetone + water) | Distillation |
| 5. Solid particles insoluble from (solvent) liquid. (Milk + Cream) | Centrifugation |
Physical and Chemical Change
| Physical Change | Chemical Change |
| (i) No new substance is formed. | A new substance is formed. |
| (ii) Properties of constituent elements/substance is retained. | Properties of constituent elements/substance changes. |
| (iii) Change does not involve loss or gain of heat. | Loss or gain of heat may be involved in this reaction. |
| (iv) This change is generally reversible. | This change is generally irreversible. |
• Solution
It is a homogeneous mixture of two or more substances.
| Solute | Solvent |
| A substance which is dissolved in a solvent. E.g., salt, sugar. |
Liquid part of solution in which is dissolved. E.g., water. |
| Solute can be solid, liquid or gas. | Solvent can be liquid, solid or gas. |
| Suspension | Solvent |
| (i) Size of soluteparticles are visible with naked eyes | Size of solute particles are not visible with naked eyes. |
| (ii) Shows tyndall effect | Shows tyndall effect |
| (iii) Translucent | Translucent |
| (iv) Solute particles settle Down | Colloidal particles do not settle down |
• Different Types of Colloids
| Dispersed Phase | Dispersing Medium | Type | Example |
| Liquid | Gas | Aerosol | Fog, clouds, mist |
| Solid | Gas | Aerosol | Smoke, automobile exhaust |
| Gas | Liquid | Foam | Shaving cream |
| Liquid | Liquid | Emulsion | Milk, face cream |
| Solid | Liquid | Solution | Milk of magnesia, mud |
| Gas | Solid | Goam | Sponge, pumice |
| Liquid | Solid | Gel | Jelly, cheese, butter |
| Solid | Solid | Solid sol | Coloured gemstone, milky glass |