Evaporation and Condensation:
In our daily life, we find different kind of substances. Either they are mixtures or pure substances. Mixtures are made up of two or more than two substances. Some of the mixtures are water soluble while some of them are not. For example: salt solution is a water soluble mixture whereas a mixture of sand and iron nails is a water insoluble mixture. The iron nails and sand mixture can be easily separated using magnetic separation methods. But in salt solution, salt and water cannot be separated so easily. The separation techniques like condensation and evaporation are used to extract water and salt separately. Let us find how evaporation and condensation helps in separating salt and water from salt solution with the help of an experiment.
Let us take a beaker full of salt solution. Heat it at a high temperature so that water present in the solution evaporates and form vapours leaving the salt crystals behind. This process of conversion of water into water vapour is known as evaporation. At the top of the beaker at some distance keep a plate so that water condenses. Make the surface of the plate inclined such that condensed water falls on the other beaker kept below.This process of conversion of water vapour into water is known as condensation.
Let us understand the concept of evaporation and condensation in details with another example of water cycle in the atmosphere. During rainy season we see that rain water is collected on top of the roof and corners of the road. But after few days it disappears. Now the question is where does it go? Rain water is heated with the help of sunlight. Water converts into vapour in the air by the process of evaporation. After some time, water vapor in the air gets cooler and converts into water droplets, as clouds. This process is known as condensation of water vapour. When air cannot hold more amount of water i.e. clouds get heavy, the water falls back on the earth’s surface as rain. This is known as precipitation. The rain water cycle is a continuous cycle.
To learn more about the separation techniques for water soluble substances and the rain water cycle, download BYJUS- the learning app.