Acids, Bases and Salts · 8 min read
Acids and their properties
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Introduction to acids
We use acids every day in Nigeria without even knowing it. When you drink a cold bottle of Coke or squeeze lime on your fish, you are tasting acids. Even the water inside your car battery is a very strong acid. In Chemistry, we study acids because they react in special ways and are very useful in factories.
What is an acid
Think of an acid as a substance that contains Hydrogen atoms. When you dissolve it in water, it releases these Hydrogen atoms as tiny charged particles called ions. It is like a generator that produces electricity; an acid is a chemical that 'produces' Hydrogen ions in water.
Simply put, an acid is any substance that gives off H^+ ions when mixed with water.
Organic and inorganic acids
There are two main groups of acids based on where they come from. Organic acids are natural acids found in plants and animals. For example, ethanoic acid is found in vinegar, and citric acid is found in lemons and oranges. These are usually weak.
Inorganic acids (also called mineral acids) are man-made from minerals. The three kings of inorganic acids you must know for JAMB and WAEC are Hydrochloric acid (HCl), Tetraoxosulphate(VI) acid (H2SO4), and Trioxonitrate(V) acid (HNO3).
Physical properties of acids
You can identify acids by these features:
They have a sour taste (like unripe mango or lime).
They turn blue litmus paper to red (remember 'ACID' ends in 'D' and 'RED' ends in 'D').
Strong acids are corrosive, meaning they can burn your skin or cloth like a hot iron.
They have a pH value less than 7.
Chemical properties of acids
Acids react in three main ways that you must memorize for your exam:
1. Reaction with metals: Acids react with active metals like Zinc or Magnesium to produce Hydrogen gas. You will see bubbles (effervescence).
2. Reaction with bases: Acids react with bases (like caustic soda) to form Salt and Water only. This is called Neutralization.
3. Reaction with carbonates: Acids react with trioxocarbonate(IV) salts (like limestone or baking soda) to release Carbon(IV) oxide gas, salt, and water.
Basicity of an acid
Not all acids are the same. Some can give away one hydrogen ion, some two, and some three. This is called Basicity.
For example, HCl has a basicity of 1 (monobasic), H2SO4 has a basicity of 2 (dibasic), and H3PO4 has a basicity of 3 (tribasic).
Key points
- •Acids produce H^+ ions as the only positive ions in water.
- •Organic acids come from living things, inorganic acids are from minerals.
- •Acids turn blue litmus paper red and taste sour.
- •Acids react with metals to liberate Hydrogen gas.
- •Basicity is the number of replaceable H^+ ions per molecule.