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Is matter around us pure | class 9 science | chapter 2 | part 3

Home School・25 minutes read

The text discusses different separating techniques in science class, including chromatography, distillation, and crystallization, each with specific applications and methods based on the properties of the substances being separated. It also distinguishes between physical changes involving the state of a compound and chemical changes resulting in a new compound with a different formula.

Insights

  • Chromatography is a technique used to separate colored components based on their solubilities in water, making it valuable for separating colors, pigments, and drugs.
  • Fractional distillation is a method crucial for separating liquids with small boiling point differences, utilizing a fractionating column connected to a condenser to condense vapors and separate liquids based on their boiling points effectively.

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Recent questions

  • What is chromatography used for?

    Separating colored components by solubilities in water.

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Summary

00:00

Separating Techniques in Science Class

  • The text is a science class discussing Chapter 2: Matter Around Us Pure, with previous videos covering separating techniques.
  • Four separating techniques have been discussed: evaporation, centrifugation, sublimation, and separation of immiscible liquids using a separating funnel.
  • The fifth separating technique introduced is chromatography, used to separate colored components by their solubilities in water.
  • Chromatography involves using a special filter paper with a drop of ink, dipped in water to observe the separation of colors based on solubility.
  • Components are separated in chromatography based on their solubilities in water, with applications in separating colors, pigments, and drugs.
  • The sixth method discussed is simple distillation, used to separate liquids with a large difference in boiling points by heating a mixture in a round bottom flask with a condenser.
  • Simple distillation requires a significant boiling point difference between the liquids to effectively separate them.
  • Fractional distillation, the seventh method, is used for liquids with a small boiling point difference, employing a fractionating column to separate them effectively.
  • Fractional distillation involves heating a mixture in a round bottom flask with a fractionating column to separate liquids with a minimal boiling point difference.
  • The process of fractional distillation allows for the separation of liquids with a small difference in boiling points by utilizing a fractionating column.

21:22

"Fractional Distillation and Crystallization in Chemistry"

  • Fractionating column is a crucial instrument connected to a condenser for fractional distillation.
  • Beads in the fractionating column aid in condensing vapors, separating liquids based on boiling points.
  • Fractional distillation is used to separate gases like oxygen, nitrogen, and hydrogen from air.
  • Air is converted into liquid by cooling and high pressure for fractional distillation.
  • Crystallization is a technique to purify solids by dissolving impure salt in a solvent and cooling to separate impurities.
  • Impurities must be dissolved in the solvent in both hot and cold conditions for crystallization to work effectively.
  • Physical changes involve only a change in the physical state of a compound, not its chemical nature.
  • Chemical changes occur when a chemical reaction leads to a change in the compound's formula.
  • Elements are pure substances made of the same type of atoms, while compounds contain different atoms in fixed ratios.
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