CBSE Class 9 Science Notes Chapter 2 Is Matter Around Us Pure:

Chapter 2 Is Matter Around Us Pure:

Notes

• Matter is anything that has mass and occupies space.

• Matter can be classified as pure substances or mixtures.

• A pure substance consists of only one type of particle and cannot be separated by physical means.

• Pure substances can be further classified as elements or compounds.

• An element is a substance that is made up of only one type of atom.

• A compound is a substance made up of two or more different types of atoms chemically combined in a fixed ratio.

• Mixtures are composed of two or more pure substances, and they can be separated into their components by physical means.

• Mixtures can be classified as homogeneous or heterogeneous.

• Homogeneous mixtures have uniform composition throughout, while heterogeneous mixtures have non-uniform composition.

• Various methods of separation of mixtures include filtration, evaporation, distillation, chromatography, and crystallization.

• Filtration is used to separate a solid from a liquid or gas.

• Evaporation is used to separate a solid dissolved in a liquid by heating the liquid.

• Distillation is used to separate two liquids with different boiling points.

• Chromatography is used to separate components of a mixture based on their relative solubility in a solvent.

• Crystallization is used to separate a solid from a liquid by cooling the liquid.

• Physical properties of a substance are those that can be observed or measured without changing the composition of the substance, such as color, texture, and melting point.

• Chemical properties of a substance describe the behavior of a substance during a chemical reaction, such as flammability, reactivity with acid, and stability.

• The melting point and boiling point of a substance are characteristic physical properties that can be used to identify the substance.

• The melting point is the temperature at which a solid changes to a liquid, and the boiling point is the temperature at which a liquid changes to a gas.

• The boiling point and melting point of a substance depend on the pressure and purity of the substance.

• Concentration is a measure of the amount of solute dissolved in a given amount of solvent.

• The solubility of a substance is the maximum amount of solute that can be dissolved in a given amount of solvent at a given temperature.

• Acids are substances that donate protons (H+) in a chemical reaction, while bases are substances that accept protons (H+) in a chemical reaction.

• pH is a measure of the acidity or basicity of a solution.

• Neutralization is a chemical reaction between an acid and a base that results in the formation of a salt and water.

•