Acids and Alkalis: The pH Scale and Neutralisation

The pH scale: This is a numerical scale, ranging from 0 to 14, which is used to measure the acidity or alkalinity of a substance. A pH of 7 is considered neutral, numbers below 7 are acidic, and numbers above 7 are alkaline (or basic).
Acids and Alkalis: Acids are substances that have a pH less than 7, while alkalis have a pH greater than 7. The closer the pH is to 0 or 14, the stronger the acid or alkali.
Acids: These substances produce hydrogen ions (H+) when dissolved in water. Common examples include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3).
Alkalis: These substances produce hydroxide ions (OH-) when dissolved in water. Common examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)2).
Neutralisation: This is the reaction between an acid and an alkali to produce a salt and water. The resulting solution is neutral (pH 7). For example, if hydrochloric acid (an acid) is added to sodium hydroxide (an alkali), sodium chloride (a salt) and water are produced.
Indicator: This is a substance used to determine the pH of a solution. It changes colour depending on whether it is in an acidic or alkaline solution. Common examples include litmus paper, phenolphthalein, and universal indicator.
Applications: Understanding the pH scale and neutralisation is fundamental in numerous areas, including industry (making fertilisers, detergents, etc.), medicine (managing drug effects), and environmental science (monitoring pollution).
Examining substances: By testing substances with indicators or a pH meter, you can determine whether they are acidic, neutral, or alkaline. This information can then be used to predict how they will behave in different situations.
Safety: It’s essential to handle acids and alkalis with care. They can be corrosive, meaning they can burn skin or eyes, and some can even be poisonous. Always use proper safety equipment when working with these substances.