Question

Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water and another containing cold water. Do not stir the solution. Allow the crystals to settle at the bottom.
i.What do you observe just above the solid crystal in the glass?
ii.What happens as time passes?
iii.What does this suggest about the particles of solid and liquid?
iv.Does the rate of mixing change with temperature? Why and how?

Answer 1

Hint:The crystals will spread at a faster rate in hot conditions, because of their higher kinetic energy. Analyze the given chemical solution and apply the facts to the statements given in the question. Write the detailed observations for the given statements.

Complete step by step answer:When we added crystals in a glass of cold and hot water, the following observations are observed:
i) In a glass of cold water, the crystals calm down to the lowest while, just in the case of hot water, it slowly spreads. The crystals are often observed dissolving within the water just above and blue/ purple color is spread into the entire solution.
ii) As time passes, the hot water becomes blue/purple and in cold water, no significant color change is observed because of less dissolution of crystals.
iii) From the above observation, we can conclude that particles of matter mix gradually with hot water. This shows the presence of intermolecular spaces in water. Particles of crystals move continuously and possess kinetic energy at a higher temperature. The particles of matter also have diffusion properties.
iv) As the kinetic energy of particles increases with the increase of temperature. So, the rate of mixing of crystals also increases as observed in the case of hot water.

Note:
Potassium permanganate is used as a disinfectant and many researchers used it to kill microorganisms. The crystals of copper sulfate are sky blue in color and the crystals of potassium permanganate are purplish bronze colored and when dissolved in water the color gets magenta rose.