The Importance of Changing One State of Matter to Another
Different mixtures can be separated through such processes as distillation, sublimation, evaporation and condensation. Let us have a look at an example of distillation. This process involves boiling, evaporation and condensation. Distillation as a process can be applied in separation of a mixture (solution) of two or more substances.
A mixture of two or more substances with different boiling points e.g. water and alcohol can be separated by this means. In such a case, a container with the mixed-up liquids is heated. The liquid with a low boiling point evaporates and condenses first, leaving the one with a high boiling point in the container. The distillate (liquid with low boiling point) is collected, cooled down and transferred into another container.
2. Industrial manufacture of products.
Industrially, the process of distillation is applied in the production of pure substances such as beer and other alcoholic drinks such as wine, vodka, konyagi, etc. The manufacturing process involves boiling, evaporating and condensation.
2. Industrial manufacture of products.
Industrially, the process of distillation is applied in the production of pure substances such as beer and other alcoholic drinks such as wine, vodka, konyagi, etc. The manufacturing process involves boiling, evaporating and condensation.
3. Refining of petroleum (crude oil).
Crude oil contains organic liquid components, each with a different boiling point. In the refinery, the components with lower boiling points evaporate first and get separated out, leaving those with higher boiling points behind. In this way, we get various types of oil components (fractions) such as petrol, diesel, kerosene, lubricating oil, etc.
4. Drying of crops and clothes.
When you suspend your clothing on a cloth line to dry, the moisture in it is lost through evaporation. Likewise, farmers in the village often spread crops on the ground to dry. They do this in order to reduce moisture content and hence prevent decaying. The moisture contained in crops leave by evaporation. Therefore, you can notice how evaporation, as a change in state, is important in everyday lives.
5. Cooling of our bodies in hot weather.
You all like to drink cold water or beverages especially during hot weather. You can use a refrigerator to cool down drinking water or beverages directly. Alternatively, you can freeze water into ice and then use the resulting ice for cooling the beverage. Ice blocks are also saleable.
Moreover, one can earn some money if she freezes water into ice blocks and then sells them to beverage vendors.
6. Ice formation in refrigerators.
You all like to drink cold water or beverages especially during hot weather. You can use a refrigerator to cool down drinking water or beverages directly. Alternatively, you can freeze water into ice and then use the resulting ice for cooling the beverage. Ice blocks are also saleable.
6. Ice formation in refrigerators.
You all like to drink cold water or beverages especially during hot weather. You can use a refrigerator to cool down drinking water or beverages directly. Alternatively, you can freeze water into ice and then use the resulting ice for cooling the beverage. Ice blocks are also saleable.
Moreover, one can earn some money if she freezes water into ice blocks and then sells them to beverage vendors. Perishable products such as fish, meat, milk, etc are often packed in ice blocks to prevent them from going bad. Ice, as we studied early, is formed when water freezes (a change in state from liquid to solid).
7. Melting metals to make alloys.
In metallurgical industries, need may arise to mix two or more metals (alloys) together. This is only possible, where two or more metals are first melted at high temperatures into liquids. Then the resulting liquid metals are mixed in appropriate proportions. This is followed by cooling down the mixture to a solid alloy. Normally alloys have better qualities than individual metals.
8. Testing the purity of substances.
The presence of impurity may lower or raise the boiling point of the substance. A pure substance melts and boils at definite temperatures (see table 5.4). The values for the melting point and boiling point are precise and predictable. This means that we can use them to test the purity of a sample. They can also be used to check the identity of unknown substance.
A typical example
Sea water is impure. It freezes at a temperature well below the freezing point of pure water (0°C) and boils at a temperature above the boiling point of pure water (100°C). Other substances behave in a similar manner. So, boiling as a change in state can be used to test for the purity of a substance.
In addition, the impurity also reduces the exactness of the melting or boiling point. An impure substance melts or boils over a range of temperature, not at a particular point.
Melting and boiling points of some pure substances
7. Melting metals to make alloys.
In metallurgical industries, need may arise to mix two or more metals (alloys) together. This is only possible, where two or more metals are first melted at high temperatures into liquids. Then the resulting liquid metals are mixed in appropriate proportions. This is followed by cooling down the mixture to a solid alloy. Normally alloys have better qualities than individual metals.
8. Testing the purity of substances.
The presence of impurity may lower or raise the boiling point of the substance. A pure substance melts and boils at definite temperatures (see table 5.4). The values for the melting point and boiling point are precise and predictable. This means that we can use them to test the purity of a sample. They can also be used to check the identity of unknown substance.
A typical example
Sea water is impure. It freezes at a temperature well below the freezing point of pure water (0°C) and boils at a temperature above the boiling point of pure water (100°C). Other substances behave in a similar manner. So, boiling as a change in state can be used to test for the purity of a substance.
In addition, the impurity also reduces the exactness of the melting or boiling point. An impure substance melts or boils over a range of temperature, not at a particular point.
Melting and boiling points of some pure substances
| Melting point (°C) | Boiling point (°C) |
Water | 0 | 100 |
Ethanol | -117 | 78 |
Oxygen | -219 | -183 |
Sodium | 98 | 890 |
Sulphur | 119 | 445 |
Iron | 1540 | 2900 |
Diamond | 3550 | 4832 |
Cobalt | 1492 | 2900 |
Nitrogen | -210 | -196 |
Propane | -188 | - 42 |
Ethanoic acid | 16 | 118 |
9. Formation of rain.
Perhaps the most important of all, as far as change in state is concerned, is the formation of rain. Rained is mainly formed through the process of evaporation and condensation. Water vapor, evaporating mostly from water bodies (oceans, seas, lakes, rivers, ponds, etc), land and plants rises up to the sky. As it rises, it cools down and condenses into tiny droplets.
On further cooling as they rise up, these droplets form bigger water drops. Owing to gravitational force, these drops fall down as rainfall. Every one of you knows how important rain is to our life. Therefore, you have noticed how evaporation and condensation, as changes in state, contribute to rain formation.
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