Advertisements
Advertisements
प्रश्न
Describe an experiment to demonstrate that water absorbs heat during boiling at a constant temperature.
Advertisements
उत्तर
BOILING POINT OF WATER AT CONSTANT TEMPERATURE:
Take some water in a beaker. Suspend and clamp a thermometer in a beaker in water so that the bulb of thermometer remains in water without touching bottom and sides of the beaker. Supply heat by the burner and note the temperature at room temperature (20°C nearly)
Record the temperature after every minute. The temperature rises and as it reaches 100°C water starts boiling. Though heat is being supplied temperature does not rise i.e. it remains constant at 100°C and bubbles formed are seen. Thus, the boiling point of water is 100°C and at boiling point heat supplied is absorbed by water at a constant temperature. Because this heat is being used to change every molecule of water into vapours.
APPEARS IN
संबंधित प्रश्न
Explain the term vaporization.
A liquid can change into vapour state at a fixed temperature.
A certain quantity of water is heated from 20°C to 100°C. Its temperature is recorded after each 1 minute. The observations are:
| Time (in minute) | Temperature (in °C) |
| 0 | 20 |
| 1 | 30 |
| 2 | 40 |
| 3 | 50 |
| 4 | 60 |
| 5 | 70 |
| 6 | 80 |
| 7 | 90 |
| 8 | 100 |
| 9 | 100 |
| 10 | 100 |
| 11 | 100 |
| 12 | 100 |
What is the physical state of water at 100°C.
Choose the correct statement of the following
Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.
Conversion of solid to vapour is called sublimation. Name the term used to denote the conversion of vapour to solid.
Assertion (A): Burning of a candle is considered a physical as well as chemical change.
Reason (R): Melting of wax is a physical change melted wax turns into vapours and then bums which is a chemical change.
A liquid changes into a gas at a constant temperature known as its ______.
Explain the terms boiling.
