(POS) Acids and Bases Lesson
Acids and Bases
When you think of acids, "sour" is likely to come to mind. For the ancient Greeks, "sour-tasting" is in fact what defined a category of substances that later became known as acids. Bases were first categorized by their uses in soaps, as well as their ability to counteract the properties of acids. In this lesson, you will learn about a few definitions of acids and bases as well as some of their properties.
Acids and bases are versatile and useful materials in many chemical reactions. Some properties that are common to aqueous solutions of acids and bases are listed in the table below:
| Acids | Bases |
|---|---|
| hydrochloric acid: HCI → H+ + CI - | sodium hydroxide: NaOH → Na+ + OH |
| nitric acid: HNO3 + H++NO3v-v - | potassium hydroxide: KOH K+ + OH |
| hydrobromic acid: HBr → H+ + Br- | calcium hydroxide: Ca(OH)2+ Ca2+ + 2 OH |
Acids are very common in some of the foods that we eat. Citrus fruits such as oranges and lemons contain citric acid and ascorbic acid, which is better known as vitamin C. Carbonated sodas contain phosphoric acid. Vinegar contains acetic acid. Your own stomach utilizes hydrochloric acid to digest food. Bases are less common as foods, but they are nonetheless present in many household products. Many cleaners contain ammonia, a base. Sodium hydroxide is found in drain cleaner. Antacids, which combat excess stomach acid, are comprised of bases such as magnesium hydroxide or sodium hydrogen carbonate.
An early way of classifying acids and bases was proposed by Svante Arrhenius, a Swedish chemist, in 1894. An Arrhenius acid is any compound that releases H+ ions when dissolved in water. An Arrhenius base is a compound that generates hydroxide ions (OH-) when dissolved in water. Some representative examples are given in the table below:
| Acids | Bases |
|---|---|
| hydrochloric acid: HCI → H+ + CI - | sodium hydroxide: NaOH Na+ + OH |
| nitric acid: HNO3 + H++NO3 - | potassium hydroxide: KOH K+ + OH |
| hydrobromic acid: HBr → H+ + Br- | calcium hydroxide: Ca(OH)2+ Ca2+ + 2 OH |
Watch the video below for an explanation of the properties of acids and bases.
Do you know the properties of acids and bases? See if you can fill in the graphic organizers below.
Properties description Links to an external site.
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