Question

Describe an experiment to show that tap water contains dissolved gases.

Answer 1

The leading gases dissolved in purified water are ${O_2}$ and ${N_2}$, $C{O_2}$, plus traces of noble gases, all in equilibrium with ambient air. If any gases are present in water, they will have a separate boiling point than water.

Complete step by step answer:
Take water during a round bottomed flask and fit a delivery tube within the flask employing a cork.
Put the opposite end of the delivery tube during an inverted graduated tube crammed with water and placed in a beaker.
On heating the water in a round bottomed flask, gas bubbles are seen escaping from the flask. These bubbles undergo the delivery and collect within the inverted graduated tube
Heat flask from Bunsen burner. Bubbles of gas will be released from the ${H_2}O$ and travel into the test tube. Continue till boiling. About half a test tube full of gas will be collected in each case all of which has been removed from solution by heating. It consists of air with a high percentage ($\%$) of oxygen.

Additional information:
I am explaining an experiment for Water contains dissolved salts also. Tap water contains dissolved salts. Take a little quantity of water during a watch glass. Keep the watch glass on a beaker heated with water. Heat the beaker. The water on watch glass will evaporate on heating. Let it cool for a few times. When the watch glass is seen in light, a variety of concentric rings of solid matter are seen. These are deposits of dissolved salts left after evaporation of water

Note: The higher the temperature of a liquid, for example ${H_2}O$, the lower its ability to dissolve gas. By just heating ${H_2}O$ it's possible to remove almost all gas from it. To make the process even more effective, constant mixing of the solution is suggested