SOLVENTS, SOLUTES & SOLUTIONS
Centuries ago, early scientists looked for a special substance they called the universal solvent. Everything that was poured into the universal solvent would dissolve- mix so thoroughly that you couldn't tell by looking that two substances had been mixed. Such a mixture is called a solution. The early scientists never found their universal solvent, but one substance, water, comes very close. As you have discovered, many substances dissolve in water.
When you pour a small amount of sugar into a glass of water, the sugar will dissolve to form a solution. In this water-sugar solution, the sugar is the solute, and the water is the solvent.
Solvent- Generally, the substance that does the dissolving.
Solute- The substance that is dissolved
Solution- Two (or more) substances mixed so thoroughly that neither can be observed in its original form.
SOME USEFUL SOLUTIONS
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MAPLE TREE SAP -Solute: sugar (solid) Solvent: water ( liquid) Solution Type: solid-liquid Use: Feeds trees and pancake-eaters |
POP- Solute : carbon dioxide (gas)Solvent: water (liquid) Solution Type: gas-liquid Use: beverage |
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WINDSHIELD WASHER -Solute: alcohol (liquid) Solvent: water (liquid) Solution: Type: liquid-liquid Use: cleans windshields |
VINEGAR- Solute: acetic acid (liquid) Solvent: water (liquid) Solution Type: liquid-liquid Use: in foods, cleaning |
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AIR :-Solute: oxygen (gas) Solvent: nitrogen (gas) Solution Type: gas-gas Use: breathing |
BRASS -Solute: zinc (solid) Solvent: copper (solid) Solution Type: solid-solid Use: decorative metal |
Characteristics of Solutions
The individual parts that make up a solution cannot be seen. A sample of a solution, no matter how small the sample is, will always appear the same as any other sample, even under a microscope. Because of this characteristic, solutions are often described as homogeneous (from "homo-" the same, and "genos," kind). Solutions look, smell, and feel as if they are made of only one substance.
Liquid and gas solutions are always transparent (you can see through them), although they are not always colourless. Apple juice and tea are examples of coloured, transparent solutions.
Solid, Liquid, and Gas Solutions
To this point, the solutions mentioned have been mostly examples of a solid dissolving in a liquid, or a liquid dissolving in another liquid. Can gases dissolved in liquids? Can solids dissolve in solids? Yes, they can. And did you know that air, a mixture of gases is a solution?
Like liquid and gas solutions, solid solutions are homogeneous. When you cut open a solid solution it will look smooth--it will be the same colour and will feel the same throughout.
Other mixtures
If a solute does not dissolve, or dissolves only partially, so some of the solute can be observed in its original form, the mixture is called a mechanical mixture. Mechanical mixtures are not homogenous--it would be possible to take two samples from a mechanical mixture that have quite different properties. As a result, mechanical mixtures are said to be heterogeneous ("hetero-"means different).
* In a mechanical mixture, it's possible to see at least two substances.
Gas solutions
1. Air - is a solution of gases that include nitrogen, oxygen, argon & carbon dioxide. There is also water vapour and tiny amounts of other gases. All of these gases are pure substances that are mixed to make a solution.
2. Neon lights - are bright lights made up of glass tubing with neon gas or other types of gases inside. When an electrical current passes through these gases, a bright orange light is created. Neon lights can be any colour if you change the colour of the glass tubing.
3. Gases for surgery - during an operation a patient must remain unconscious. A gas solution of oxygen and other gases such as, nitrous oxide, are given to the patient to keep them asleep during the operation.
4. Gases for burning - Natural gas is used for cooking & heating. Natural gas is actually a solution of several gases. With methane as its solvent.
Solution that are solid
Alloy - most metals are a combination of two or more metals mixed together to form a solid solution. These metals are called alloys. Alloys allow scientists & engineers to design metals for specific purposes.
Example:
Steel is created by taking iron from iron ore and carbon from coal. Chromium and nickel can be added to make the steel resistant to rust (stainless steel). All of these metals are mixed to create a solid solution.
Adding zinc and copper together makes brass. Brass is an alloy that is strong and resistant to rust.
- Ceramics: a solution made from silica (beach sand)
- Plastics: a modern solid solution. Plastic is used to make many different types of products. Oil is the main raw material for making plastic products.