Water Class 9 Chemistry | Selina Chapter 3 | Universal Solvent, Saturated, Supersaturated Solution

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Shubham offers free educational content on Chemistry, Maths, and Biology at lonav.com, specifically focusing on Class Ninth Chemistry concepts related to water as a universal solvent, solutions, solubility, and saturated solutions. The video lecture explains how temperature influences solubility, the differences in solubility levels among substances, and the unique properties of saturated and supersaturated solutions, highlighting the importance of understanding these concepts in chemistry.

Insights

  • Water's universal solvent property allows it to dissolve a wide range of substances, forming solutions with uniform distribution of components.
  • Solubility, influenced by temperature, determines the maximum amount of solute that can dissolve in a solvent, with increasing temperature generally increasing solubility but excessive heating causing evaporation and reduced solubility.

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Summary

00:00

"Free Chemistry, Maths, Biology Education at lonav.com"

  • Shubham offers free educational content on Chemistry, Maths, and Biology at lonav.com.
  • The video lecture focuses on Class Ninth Chemistry, specifically on the concepts of water.
  • Topics covered include water as a universal solvent, solutions as mixtures of solids in water, the effect of temperature on solubility, and saturated solutions.
  • Water is highlighted as a universal solvent due to its ability to dissolve a wide range of substances.
  • The concept of solutions is explained as a homogeneous mixture with uniform distribution of components.
  • Binary solutions are discussed, with water often acting as the solvent, leading to aqueous solutions.
  • Saturated solutions are defined as those where no more solute can dissolve at a particular temperature.
  • Solubility is described as the amount of solute that can dissolve in 100 grams of solvent at a specific temperature.
  • The unit of measurement for solubility is typically in grams.
  • Understanding saturated solutions is crucial before delving into the concept of solubility.

15:10

Solubility and Temperature Relationship in Substances

  • Different substances dissolve in different amounts based on the solvent and temperature.
  • Solubility varies among substances, with some being more soluble than others.
  • Solubility can be categorized as very soluble, sparingly soluble, or insoluble based on the amount dissolved in a particular solvent.
  • Solubility is influenced by temperature, with higher temperatures generally increasing solubility.
  • Increasing temperature can lead to higher solubility due to the increased space between solvent particles.
  • However, excessive heating can cause the solvent to evaporate, reducing solubility.
  • The solubility curve graphically represents how solubility changes with temperature for a specific substance.
  • The solubility curve shows the relationship between temperature and the amount of substance dissolved.
  • By analyzing the solubility curve, one can determine the solubility of a substance at different temperatures.
  • The solubility of substances like potassium nitrate and sodium chloride can significantly increase with temperature changes.

29:28

Temperature's Impact on Solubility and Crystallization

  • Starting with 30 grams at 0 degrees Celsius, the solubility of calcium sulphate dot 2h2o is unique, increasing slightly to around 40 grams.
  • Hydrated calcium sulphate is formed when water molecules are present with the substance, known as water of crystallization.
  • Solubility increases with temperature due to the increased kinetic energy of solvent molecules, creating more space for solute particles.
  • Solubility of potassium nitrate and sodium chloride increases with temperature until a certain point, after which it decreases.
  • Increasing temperature leads to the evaporation of water, causing the solute to come out of the solution, reducing solubility.
  • Lowering the temperature decreases solubility, causing the solute to come out of the solution as solid crystals.
  • Saturated solutions reach their maximum capacity at a specific temperature, while unsaturated solutions can dissolve more solute by increasing solvent volume.
  • Increasing temperature can turn a saturated solution into an unsaturated one by allowing more solute to dissolve.
  • Decreasing temperature reduces solubility, causing the solute to come out of the solution as solid crystals.
  • Supersaturated solutions, like sodium acetate, can remain stable even after reducing the temperature below the saturation point, a unique phenomenon.

42:28

"Understanding Supersaturated Solutions and Solubility"

  • A supersaturated solution contains more solute than a saturated solution, leading to disorder in the solution.
  • The definition of a supersaturated solution involves the maximum amount of solute capable of being dissolved at a specific temperature.
  • The maximum amount of solute in a saturated solution is the same as the amount that can be dissolved at any given temperature.
  • The example of sodium chloride at 25 degrees Celsius illustrates the concept of solubility.
  • Increasing the temperature of a solution can lead to more solute dissolving due to increased solubility.
  • Adding more solute beyond the maximum limit results in the solution becoming saturated.
  • Triggering the crystallization process in a supersaturated solution involves introducing a small crystal to initiate the formation of salt crystals.
  • A practical question involves identifying which substances do not dissolve in raindrops, river water, or well water, emphasizing the concept of solubility.
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