Acids are substances that donate protons (H+) while bases are substances that accept protons (H+). One of the most important properties of acids and bases is their pH value which measures the concentration of hydrogen ions in a solution.

The pH scale ranges from 0 to 14. A pH of 7 is considered neutral, pH values below 7 indicate an acidic solution and pH values above 7 indicate a basic solution.

- In an acidic solution, the concentration of H+ ions is higher indicating that the solution has more hydrogen ions and fewer hydroxide ions (OH-)

- In a basic solution, the concentration of H+ ions is lower indicating that the solution has fewer hydrogen ions and more hydroxide ions (OH-).

The pH difference between acids and bases is essentially the difference in hydrogen ion (H+) concentration between the two solutions. The higher the H+ ion concentration, the lower the pH value, and the higher the OH- ion concentration, the higher the pH value.

The strength or intensity of acids and bases is also related to their pH values. Strong acids or bases completely dissociate in water resulting in a high concentration of H+ ions or OH- ions and extreme pH values. Weak acids or bases only partially dissociate in water resulting in a lower concentration of H+ or OH- ions and less pronounced pH values.