Quick Revision Notes & Formula Sheet

Class 9 Science - Chapter: Is Matter Around Us Pure

MP Board Education

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### 1. Important Definitions & Basic Concepts

• Matter (पदार्थ): Anything that occupies space and has mass.
• Pure Substance (शुद्ध पदार्थ): Consists of a single type of particles (atoms or molecules) having a fixed set of properties.
• Mixture (मिश्रण): Composed of two or more pure substances mixed together in any proportion, retaining their individual properties.
• Solution (विलियन): A homogeneous mixture of two or more substances.
• Solute (विलेय): The component of the solution that is dissolved in the solvent (usually present in lesser quantity).
• Solvent (विलायक): The component of the solution that dissolves the solute in it (usually present in greater quantity).

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### 2. Types of Mixtures

• Homogeneous Mixture (समांगी मिश्रण): A mixture having a uniform composition throughout (e.g., salt in water, sugar in water).
• Heterogeneous Mixture (विषमांगी मिश्रण): A mixture having non-uniform composition and visible boundaries of separation (e.g., oil in water, sand and salt).

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### 3. Types of Solutions based on Saturation

• Unsaturated Solution: A solution in which more quantity of solute can be dissolved at a specific temperature.
• Saturated Solution: A solution in which no more solute can be dissolved at that specific temperature.
• Solubility (विलेयता): The maximum amount of solute that can be dissolved in 100g of a solvent at a specified temperature.

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### 4. Key Formulas for Concentration of Solutions

The concentration of a solution is the amount of solute present in a given amount of solution.

A. Mass by Mass Percentage (% w/w)

$$\text{Mass percentage of solution} = \left( \frac{\text{Mass of Solute}}{\text{Mass of Solution}} \right) \times 100$$ (Note: Mass of Solution = Mass of Solute + Mass of Solvent)

B. Mass by Volume Percentage (% w/v)

$$\text{Mass by volume percentage} = \left( \frac{\text{Mass of Solute}}{\text{Volume of Solution}} \right) \times 100$$

C. Volume by Volume Percentage (% v/v)

$$\text{Volume percentage} = \left( \frac{\text{Volume of Solute}}{\text{Volume of Solution}} \right) \times 100$$

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### 5. Comparison of Colloids, Solutions, and Suspensions

Property	True Solution	Suspension	Colloid
Nature	Homogeneous	Heterogeneous	Heterogeneous (appears homogeneous)
Particle Size	Less than 1 nm	More than 100 nm	Between 1 nm and 100 nm
Tyndall Effect	Does not show	May or may not show	Shows
Separation	Cannot be filtered	Can be filtered out	Passes through filter paper (separated by centrifugation)
Stability	Stable	Unstable	Stable

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### 6. Methods of Separation of Mixtures

• Evaporation (वाष्पीकरण): To separate a volatile component (solvent) from a non-volatile solute (e.g., salt from sea water).
• Centrifugation (अपकेंद्रीकरण): To separate dense particles from lighter particles in a liquid using a centrifuge (e.g., cream from milk).
• Sublimation (ऊर्ध्वपातन): To separate mixtures containing a sublimable volatile component from a non-sublimable impurity (e.g., camphor and salt).
• Chromatography (क्रोमैटोग्राफी): To separate solutes that dissolve in the same solvent (e.g., colors in black ink).
• Distillation (आश्वन): To separate miscible liquids boiling at different temperatures with a significant difference.
• Fractional Distillation (प्रभावी आश्वन): To separate two or more miscible liquids where the difference in boiling points is less than 25K (e.g., separation of gases from air).
• Separating Funnel (पृथक्कारी कीप): To separate immiscible liquids (e.g., oil and water).

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### 7. Physical vs. Chemical Changes

• Physical Change (भौतिक परिवर्तन):
  • No new substance is formed.
  • Temporary and reversible.
  • Example: Melting of ice, boiling of water, dissolving salt in water.
• Chemical Change (रासायनिक परिवर्तन):
  • A new substance with different properties is formed.
  • Permanent and usually irreversible.
  • Example: Burning of paper, rusting of iron, cooking of food.