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Matter in the Universe
That matter may exist in three physical states (solid, liquid and gas) is a common knowledge. It is usually possible to change matter from one state to the other by changing its temperature. For instance, a piece of ice is called a solid; it may melt and form a liquid; as it evaporates, liquid water changes into a vapour, i. e. into the gaseous state.
Many kinds of matter, like water, can be obtained in each of the three states; for some, however, extraordinary means have to be used in order to produce one, or even two of the states; and for others, only two states are known or can be produced.
Common salt, for example, exists normally as a solid; at a temperature of several hundred degrees, it can be liquefied; and at still higher temperature it is converted into vapour. Carbon, a solid under normal conditions, can be vaporized, but it has never been liquefied.
Solids have both a definite volume and a definite shape. Liquids, too, have a definite volume, but they take the shape of their containers.
Gases have neither a definite shape nor a definite volume. A chemist must have a thorough knowledge of the states of matter and of physical laws that govern the behavior of matter in various states.
That all matter is composed of molecules is known to everybody. The question which must be answered, then, is: if all matter is composed of molecules, what is the essential difference between the states of matter? The answer to this question is that the essential difference between these states is the relative quantities of energy molecules possess in different states.
1. How is it usually possible to change matter from one state to the other?
2. Can all kinds of matter be obtained in each of the three states?
3. What do solids have?
4. What characterizes gases?
5. Why should a chemist know the states of matter?
6. What other substances besides water can be obtained in the three states?
Ответы
Ответ:
1. How is it usually possible to change matter from one state to the other?
It is usually possible to change matter from one state to the other by changing its temperature.
2. Can all kinds of matter be obtained in each of the three states?
Not all. Many kinds of matter, like water, can be obtained in each of the three states.Common salt, for example, exists normally as a solid; at a temperature of several hundred degrees, it can be liquefied. Carbon, a solid under normal conditions, can be vaporized, but it has never been liquefied.
3. What do solids have?
Solids have both a definite volume and a definite shape.
4. What characterizes gases?
Gases have neither a definite shape nor a definite volume.
5. Why should a chemist know the states of matter?
A chemist must have a thorough knowledge of the states of matter and of physical laws that govern the behavior of matter in various states.
6. What other substances besides water can be obtained in the three states?That matter may exist in three physical states (solid, liquid and gas) is a common knowledge.
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