Solutions of Acids

• Solutions of acids can be classified as dilute or concentrated, signifying how much solute (acid) is dissolved in a solvent (often water).

• When an acid enters into a solution, it donates a hydrogen ion (H+), known as a proton. This behaviour defines acids as ‘proton donors’.

• The pH scale is used to measure the acidity or basicity of a solution. For solutions of acids, the pH will be less than 7.

• When acids are dissolved in water, they form hydrogen ions, H+(aq). For example, Hydrochloric acid (HCl) dissociates to form H+ and Cl- ions.

• Concentrated and strong are two different concepts, a strong acid fully ionises in water while concentration relates to the amount of acid particles present in a given volume.

• Acid solutions react with metals, bases and carbonates to produce salts.

• Different acids produce different salts - sulfuric acid produces sulphates, nitric acid produces nitrates and hydrochloric acid produces chlorides.

• The reactivity of an acidic solution with a base or alkali depends on the strength of the acid (how completely it ionises in solution) and the concentration of H+ ions in the solution.

• Universal indicator or litmus paper is used to test acid solutions. A colour change to red indicates pH is less than 7 for universal indicator while it turns litmus paper red.

• Finally, when dealing with solutions of acids, safety is paramount. Always wear eye protection and take care when handling these substances as they can be corrosive.