Chemical Changes: Acids and Bases

Acids and bases are pivotal elements of the Chemistry syllabus. Understanding them aids in comprehending various essential chemical reactions.
Acids are substances that produce hydrogen ions (H+) when dissolved in water. Notable examples include hydrochloric acid (HCl), sulphuric acid (H2SO4), and nitric acid (HNO3).
Acids react with some metals to form a salt and hydrogen gas. The general equation for this type of reaction is: Acid + Metal -> Salt + Hydrogen.
Bases are substances that can accept hydrogen ions. Many bases are metal oxides or metal hydroxides. Examples are copper oxide (CuO) and sodium hydroxide (NaOH).
When acids and bases react with each other, they undergo a neutralisation reaction. The products are a salt and water. The general equation for this type of reaction is: Acid + Base -> Salt + Water.
The pH scale is a measure of how acidic or basic a solution is. This scale ranges from 0 (very acidic) to 14 (very basic), with 7 considered neutral.
Strong acids fully ionise in water, releasing a high concentration of hydrogen ions. Weak acids only partially ionise, releasing a lower concentration of hydrogen ions.
Alkalis are bases that dissolve in water to produce hydroxide ions (OH-). Common examples include sodium hydroxide and potassium hydroxide.
Indicators are used to determine whether a solution is acidic, neutral, or basic. Litmus turns red in the presence of acids and blue in the presence of bases. Other indicators include phenolphthalein and methyl orange.
The strength of an acid or alkali refers to its degree of ionisation. ‘Strength’ and ‘concentration’ should not be confused, though; even a dilute solution of a strong acid, for example, is strong because it fully ionises.
Soluble salts can be made by reacting acids with metals, bases, or carbonates. The process often involves reaction, filtration, evaporation, and crystallisation.
Salts are named depending on the reactants involved. The first part of the salt’s name comes from the metal in the base, carbonate, or metal that reacted with the acid, while the second part comes from the acid used.