Final answer:
The pH scale measures the acidity or basicity of a solution. Acids have pH less than 7, bases have pH greater than 7, and neutral solutions have a pH of 7.
Step-by-step explanation:
The pH scale is a measure of the acidity or basicity of a solution. It is a range of values from 0 to 14, with 0 being the most acidic, 7 being neutral, and 14 being the most basic. pH measures the concentration of hydronium (H3O+) or hydrogen (H+) ions in an aqueous solution.
An acid is a substance that donates hydrogen ions, increasing the concentration of H3O+ ions in a solution. Examples of acids include vinegar (acetic acid) and lemon juice (citric acid). Acids have pH values less than 7 on the pH scale.
A base is a substance that accepts hydrogen ions, decreasing the concentration of H3O+ ions in a solution. Examples of bases include baking soda (sodium bicarbonate) and ammonia. Bases have pH values greater than 7 on the pH scale.