Figure 33 - The boiling point is lowered by

The reduction of the pressure above the liquid

The Influence of pressure on the boiling point can be shown by filling a flask (Figure 33) half full of water and boiling it vigorously for some time to remove the air from above the water. Insert a rubber stopper in the flask, rendering the flask airtight. Remove the flask immediately from the flame. Invert the flask, and pour cold water on the bottom. This cold water will cause some of the vapor in the flask to condense, and the pressure on the hot water in the flask will be reduced sufficiently to allow the water to begin boiling again [2, С. 89 - 91].

True or false?

1. Different substances have different melting points.

2. Freezing point is such a temperature that, for example, is required to turn water into ice.

3. To find the heat of fusion of a substance we should find the number of calories necessary to convert 1 g at the melting point into solid at the same temperature.

4. We can change the melting point of a substance with the help of pressure.

5. The pressure of the saturated vapor at boiling point is greater then the pressure of the atmosphere on the surface of the liquid.

6. The boiling point does not depend on the outside pressure.

Read the text, translate it and give the definitions to convection and conduction.

<== попередня сторінка	\|	наступна сторінка ==>
Read the text, translate it and answer which sentences below are true and which are false.	\|	Transfer of Heat

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