Factors affecting the rate of dissolving in Is Matter Pure – Class 9 Science Experiment

Chapter Name: Is Matter Pure

Activity Name: Factors affecting the rate of dissolving in Is Matter Pure

Activity Description:

This experiment aims to investigate the factors affecting the rate of dissolving, specifically focusing on the impact of temperature and solute size (powder vs. crystals) on the dissolution process.

Required Items:

  1. Three glass beakers
  2. Water (approx. 300 ml)
  3. Table salt (sodium chloride) powder
  4. Table salt (sodium chloride) crystals
  5. Stirring rod or spoon
  6. Heat source (e.g., hot plate or Bunsen burner)

Step by Step Procedure:

  1. Take three glass beakers and label them as Beaker A, Beaker B, and Beaker C.
  2. Fill each beaker with 100 ml of water.
  3. Add two spoons of salt powder to Beaker A, Beaker B, and Beaker C.
  4. Leave Beaker A undisturbed (no stirring or heating).
  5. Stir the solution in Beaker B using a stirring rod or spoon.
  6. Warm Beaker C by placing it on a heat source (e.g., hot plate or Bunsen burner) and carefully increasing the temperature.
  7. Observe the dissolving process in each beaker for a few minutes.

Experiment Observations:

  1. Beaker A (no stirring, no heating): The salt powder dissolves slowly, and some undissolved particles may remain at the bottom.
  2. Beaker B (stirring): The salt powder dissolves at a moderate rate, and stirring helps in speeding up the dissolution process.
  3. Beaker C (heating): The salt powder dissolves relatively quickly as the warm temperature increases the kinetic energy of the particles, promoting faster dissolution.
  4. When using salt crystals instead of salt powder:
  5. Beaker A (no stirring, no heating): The salt crystals dissolve slowly, and some undissolved crystals may remain.
  6. Beaker B (stirring): The salt crystals dissolve at a faster rate than in Beaker A due to the stirring action.
  7. Beaker C (heating): The salt crystals dissolve even more rapidly in the warm water compared to Beaker B.

Precautions:

  • Use caution when handling the heat source to avoid burns or accidents.
  • Stir gently to avoid splashing the solution.
  • Ensure accurate measurements of water and salt to maintain consistency across the beakers.
  • Dispose of the solution safely after the experiment.

Lesson Learnt from Experiment:

The experiment demonstrates that the rate of dissolving is influenced by two main factors: temperature and the size of the solute particles. Increasing the temperature of the solvent accelerates the dissolution process, as higher temperature results in greater kinetic energy of the particles, leading to more effective collisions between solute and solvent molecules.

Additionally, using smaller solute particles (powder) also enhances the rate of dissolving compared to larger particles (crystals), as more surface area is exposed to the solvent, allowing for more effective interactions.

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