Question

Take a beaker with some water and place a lighted candle in standing position in it.Now cover the candle with a test tube to cut off it air supply.For how long does the candle keep on burning? How much water rises up in the test tube?Why did it happen so?Explain with diagram. You can perform this experiment with utensils available at your home in case of non availability of the beaker and test tube.

Answer 1

Answer:

The candle will stop burning as the oxygen supply is cut and the water will rise a little in test tube.  

Explanation:

Because twice as much oxygen is burned than carbon dioxide released, the air volume decreases.  This cancels the depletion of the oxygen temporarily and the water level stays down. When the oxygen is depleted, the candle goes out and the air cools. The volume of the air decreases and the water rises. The evaporation of the water to water vapor as the candle burns, and the cooling that occurs when the candle goes out, cause lower air pressure inside the glass than outside. The water is pushed into the glass until equilibrium is reached.) Air cools when the flame goes out.