Tagged: Particulate Nature of Matter

Nutshell: Diffusion

Diffusion is the movement of particles from region of higher concentration to lower concentration.

Diffusion can occur in solids, liquids and gases. Rate of diffusion is greatest in gases and then followed by liquids. Rate of diffusion is least in solids.


List: Volatile Liquids

Volatile liquids have low boiling point. As a result, they evaporate very easily at room temperature. Because of their low boiling points, volatile liquids convert to the gas phase at a lower temperature and the gas molecules can diffuse faster than the molecules of a non-volatile liquid. This is the reason why perfumes use volatile liquids so that their scent can disperse more quickly into the air.

When volatile liquids come in contact with human skin, it gives us a cooling sensation.

Some other examples of volatile liquids include acetone, ammonia, dichloromethane, and diethylether.

Examples of volatile liquids:

  • alcohol
  • petrol
  • methylated spirits
  • acetone
  • chloroform
  • List: Substances that undergoes sublimation

    These are some common substances that undergo sublimation upon heating under the normal atmospheric pressure condition.

  • dry ice (solid carbon dioxide)
  • iodine crystals
  • napthalene (mothballs)
  • camphor
  • *ammonium chloride
  • *ammonium chloride doesn’t actually undergo sublimation upon heating. It decomposes and forms ammonia gas and hydrogen chloride gas. When they are in contact with cooler surfaces, they recombine to form back ammonium chloride. This gives a false impression that it has undergone sublimation.

    -decomposition of ammonium chloride-

    NH4Cl → NH3 + HCl

    Q&A: Condensation

    What is condensation and what are the conditions required for condensation to take place ?

    Condensation is a process where a gas changes state into the liquid state. This happens when the warmer gas is in contact with a cooler surface. The gas condenses on the surface and forms the liquid state.

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