How does pH affect ethanoic acid reactivity?

The pH level affects the reactivity of ethanoic acid by influencing its ionisation and hence, its ability to donate protons.

Ethanoic acid, also known as acetic acid, is a weak acid. This means it does not fully ionise in water, unlike strong acids. The ionisation of ethanoic acid is a reversible process, represented by the equation: CH3COOH ⇌ CH3COO- + H+. The pH of a solution is a measure of the concentration of hydrogen ions (H+). Therefore, the pH of the solution can affect the position of this equilibrium and thus, the reactivity of the ethanoic acid.

In a low pH environment (acidic conditions), there is a high concentration of H+ ions. This excess of H+ ions will shift the equilibrium to the left, according to Le Chatelier's principle. This means that less ethanoic acid will ionise, reducing its reactivity as there are fewer ethanoate ions (CH3COO-) and H+ ions available to react.

Conversely, in a high pH environment (alkaline conditions), there is a low concentration of H+ ions. This deficiency of H+ ions will shift the equilibrium to the right, causing more ethanoic acid to ionise. This increases its reactivity as there are more ethanoate ions and H+ ions available to react.

It's also important to note that the reactivity of ethanoic acid is not just dependent on pH, but also on factors such as concentration and temperature. However, understanding the effect of pH on the reactivity of ethanoic acid is crucial in predicting how it will behave under different conditions. This knowledge is particularly useful in various applications, from industrial processes to food preservation.