Concept of pH

Concept of pH

The history of the concept of pH?

The concept of   pH was introduced first by Søren Sørensen, a Danish Chemist, in 1909. It was introduced as a convenient way to express acidity. Until the pH scale was developed, there was no other accurate and widely accepted method of expressing hydrogen ion concentrations. The concept of pH entailed a gradual conversion from the old tests of colour changing to electrical methods. In this electrical technique, the current generated in electrochemical cells by the migration of ions to oppositely charged electrodes is gauged using a highly sensitive galvanometer. Sørensen was helped by his wife Margrethe Høyrup Sørensen in this.

What is the concept of  pH?

The concept of  pH is a quantitative measure of acidity or basicity of an aqueous or any other liquid solution. The concept of pH involves using the pH scale for measuring the acidity or alkalinity of any solution. The pH scale ranges from 0-14. This concept of pH and pH measurement was developed first by a Danish Scientist. Any aqueous solution at 25°C having a pH less than seven is characterized as ‘Acidic.’ Any solution having a pH level of 7.0 at 25°C is characterized as ‘Neutral.’ Very strong bases can have a pH greater than 14. While very strong acids might have a negative pH.

pH Definition

Technically defined, pH is the negative logarithm of H+ ion concentration. Thus, pH means the power of hydrogen. Everyone knows that all acids and bases react differently with the same chemical compound, even at the same rates. Some might react vigorously, some might react moderately, while others show absolutely no reaction. This is where the concept of pH and pH measurement comes in to help. Quantitatively, a universal indicator is used to determine the acid strength and base strength, which works by showing different colours at different concentrations of the hydrogen ions in the solution. Most commonly, the value of pH of bases and acids is used to determine their quantitative strength.

The pH Meter

The pH of any substance is usually measured using a pH  meter. A pHmeter works by translating the differences in electromotive forces between any suitable electrodes that are placed in the solution to be tested into pH readings. It consists of a voltmeter attached to a pH-responsive electrode and a reference electrode. The pH responsive electrode is often glass, and the reference is usually a calomel electrode. Although, a silver-silver chloride electrode may be used sometimes. When immersed in the solution, the two electrodes act as a battery. The glass electrode then develops an electric potential directly related to the hydrogen-ion activity in that solution. The voltameter then measures the potential difference between the reference and the glass electrodes. The meter can have either a digital or an analogue readout. Digital readouts are more exact, while analog readouts give a better indication of the rates of change. These battery-powered pH meters are commonly used for testing the pH of soils. Although, pH tests can also be performed at home, less accurately, by using litmus paper or mixing indicator dyes in liquid suspensions and then matching the colours against a colour chart calibrated in pH.

The Importance of pH

The concept of pH and pH measurement plays a crucial role in our overall well-being. Doctors and scientists universally agree on this as well. The pH level or the possible hydrogen level in one’s body is determined by the type of food and drink one consumes. It thus becomes vital for us to help our body create and maintain a healthy pH ratio of 70:30, that is, alkaline to acid. Most diseases, illnesses, and harmful bacteria can thrive in over-acidic environments. Unbalanced pH levels usually result from the pH being too acidic.

pH Equation

In 1999, Danish biochemist, Søren Sørensen, proposed the equation for calculating pH.

pH = – log[H+]

• where log is the base-10 logarithm
•  [H+] stands for the hydrogen ion concentration in units of moles per litre solution. The word pH is derived from the German word “potenz,” meaning “power,” combined with H, the element symbol for hydrogen. Thus, pH is an abbreviated word for “power of hydrogen.”

Examples of pH Values of Common Chemicals

Some examples of pH values of lab chemicals and household products are:

• Hydrochloric Acid : 0
• Lemon Juice: 2.0
• Vinegar: 2.2
• Wine: 4.0
• Pure Water (Neutral): 7.0
• Human Blood: 7.4
• Lye: 13.0
• Sodium Hydroxide: 14.0

Conclusion

A Danish scientist gave the concept of pH. The concept of pH is used to specify the acidity or basicity of an aqueous solution. Acidic solutions have a higher pH value than basic or alkaline solutions. The pH scale inversely indicates the concentration of the hydrogen ions in a solution. Solutions at 25°C having pH less than 7 are acidic, while solutions with pH greater than 7 are classified as basic.

pH  can also be tested at home using litmus paper or indicator dyes, although the results are not highly accurate. pH is scientifically measured using a pH meter. This pH meter delivers exact pH readings. The pH meter is the tool used for measuring required pH levels. The concept of pH is prevalent in everyday life and science, and various industries. If water’s pH is too high or too low, it will cause the death of any aquatic animals present. The pH can also affect the solubility and toxicity of chemicals and heavy metals in the water. It is present in cooking, baking, designing cocktails, etc. It is also crucial in pool maintenance, water purification, chemistry, agriculture, medicine, oceanic sciences, etc.