Know what makes a solution acidic or basic (the pH number and the ions).

To determine whether an acidic or basic solution, it is first necessary to compare the concentrations of the hydronium (H3O + ) and hydroxide (OH-) ions in the solution.

In acidic solution, the concentration of H3O + ions is higher than that of OH - ions.

In acidic solution, the concentration of H3O + ions is higher than that of OH - ions. Such a solution can be achieved by adding a small part of the H3O + ions, for example. Acid solutions have a pH below 7, the further away from 7 the pH of the solution is the higher its acidity content. According to Le Chatelier's principle, when a disturbance is caused to an equilibrium system, it tends to readjust in order to diminish the effects of that force. This means that if an acid is added to water, the H3O + ions will be in excess and the equilibrium will shift in the opposite direction to the left. Then these excess ions will react with the OH - ions. Thus, the concentration of OH - ions will decrease and the solution will become acidic. In basic solutions, the concentration of OH - ions is higher than that of H3O + ions. If we add a base to the water, it means that we will be adding OH - ions and, as explained in the previous section, by Le Chatelier's principle, the equilibrium of the water selfionization reaction will shift in the opposite direction, and the excess ions will react. with the H3O + ions, decreasing their concentration and making the basic solution. Basic solutions have a pH greater than 7, the farther from 7 and closer to 14 the pH of the solution, the higher the basification content.