The pH scale measures the acidity and alkalinity of aqueous solutions. The values of the scale ranges from 0-14. 0 being very acidic, and 14 being very alkaline, The pH number of 7 is neutral. A solution with the pH of 7 is neither an acid or an alkaline. One example of a neutral solution is pure water. This is why when mixing chemicals in pure water, the pure water does not affect the pH of the solution. Acids produce more hydrogen ions (H+) when dissolved in water while alkalis produce more hydroxide (OH-). The greater the concentration of H+ ions, the more acidic and lower the pH of the solution. Likewise, the greater the concentration of OH- ions, the more alkaline and higher the pH of the solution. When we mix acids and alkalis, the H+ ions and the OH- ions will be able to be balanced out. The pH of a cleaning agent does not represent the strength of the cleaning agent nor its performance. The pH value simply represents the acidity or alkalinity of a solution measured on a scale of 0-14. It does not mean that cleaning agent of a higher pH will perform or clean better. When we clean, we are trying to neutralize the impact of the hydrogen and hydroxide ions. Depending on whether the soils are acidic or alkaline, we can choose the best cleaning agents to use. For example, if we want to clean up pet urine which has dried, it is better to use an acidic cleaning agent as dry pet urine is alkaline. The acidic cleaning agent would be able to neutralize the pet urine. Thus, making it a better choice. However, if we want to remove a coffee stain, it would be advisable to use an alkaline cleaning agent, as the pH of coffee (pH value of black coffee is around 5) is on the acidic side of the pH scale. An alkaline cleaning agent would work best in this case. Most stains are acidic in nature, due to the combination of substances like dust, dirt and oily substances. Thus, most cleaning agents are alkali. There are several ways to test if the cleaning agent is acidic or alkaline. To test if the cleaning agent is an acid or alkaline, the simplest way is to use litmus paper. To test if the cleaning agent is an acid, use blue litmus paper and place it in the solution. If the blue litmus paper turns red, the cleaning agent is acidic. Likewise, to test if the cleaning agent is an alkaline, use red litmus paper and place it in the solution. If the red litmus paper turns blue, the solution is alkaline. We can also use Universal Indicator solution or Universal Indicator paper to determine the pH value of the cleaning agent.