What is the difference between strong and weak acids?

Strong acids fully ionise in water, while weak acids only partially ionise. This difference affects their reactivity and pH levels.

Strong acids are substances that completely ionise in water. This means that when a strong acid is added to water, all of its molecules break apart and release hydrogen ions (H+). Examples of strong acids include hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid (H2SO4). Because they fully ionise, strong acids tend to have a low pH (below 7) and are highly reactive, making them useful in various chemical reactions.

On the other hand, weak acids only partially ionise in water. This means that when a weak acid is added to water, only a small fraction of its molecules break apart to release hydrogen ions. The rest of the molecules remain intact. Examples of weak acids include acetic acid (found in vinegar) and citric acid (found in citrus fruits). Because they only partially ionise, weak acids tend to have a pH closer to 7 and are less reactive than strong acids.

The difference in ionisation also affects the conductivity of the solution. Since ionisation produces ions, which are charged particles, a solution of a strong acid will conduct electricity better than a solution of a weak acid. This is because the greater number of ions in the strong acid solution allows for easier movement of charge.

In summary, the main difference between strong and weak acids lies in their degree of ionisation in water, which in turn affects their reactivity, pH levels, and conductivity.