Inorganic chemistry

What is pH and it’s uses?

pH equation?

 pH equation values and measurement

Definition of pH and equation in chemistry

pH equation values and measurement are listed below

 What is pH?

pH is a measure of the concentration of hydrogen ions ; a measure of the acidity or alkalinity of a solution.pH scale generally ranges from 0 to 14. Aqueous solutions at 25 ° C with a pH below 7 are acidic , while those with a pH above 7 are basic or alkaline . A pH level of 7.0 at 25 ° C is defined as ” neutral ” because the concentration of H 3 O + is equal to the concentration of OH  in pure water.

Very strong acids can have a negative pH , while very strong bases can have a pH above 14.PH scale

PH equation

The equation for calculating the pH was proposed in 1909 by the Danish biochemist Søren Peter Lauritz Sørensen:

pH = -log [H + ]

where log is the base logarithm 10 and [H + ] represents the concentration of hydrogen ions in units of moles per liter of solution. The term “pH” comes from the German word potenz , which means “power” combined with H, the symbol element for hydrogen, so that pH is an abbreviation for “hydrogen power”.


 pH values ​​for common chemicals examples

Every day we work with many acids (low pH) and bases (high pH) . Examples of pH values ​​for laboratory chemicals and household products:

0 – hydrochloric acid
2.0 – lemon juice
2.2 – vinegar
4.0 – wine
7.0 – pure (neutral) water
7.4 – human blood
13.0 – detergent
14.0 sodium hydroxide

Not all liquids have a pH value

PH only makes sense in an aqueous solution (in water).

Many chemicals, including liquids, do not have pH values. If there is no water, there is no pH! For example, there is no pH value for vegetable oil , gasoline or pure alcohol.

 Definition of pH IUPAC

The International Union of Pure and Applied Chemistry (IUPAC) has a slightly different pH scale which is based on electrochemical measurements of a standard buffer solution.

Essentially, the definition using the definition:

pH = -log a H +

where H + represents the activity of hydrogen, which is the effective concentration of hydrogen ions in a solution. It may be slightly different from real concentration. The IUPAC pH scale also includes thermodynamic factors that can influence pH.

For most situations, the standard definition of pH is sufficient.

How pH is measured?

Approximate pH measurements can be made using litmus paper or another type of pH paper which is known to change colors around a certain pH value. Most pH indicators and papers are only useful for telling whether a substance is an acid or a base or for identifying the pH in a narrow range. A universal indicator is a mixture of indicator solutions intended to provide a color change over a pH range of 2 to 10. More precise measurements are made using primary standards to calibrate a glass electrode and a pH meter. The electrode works by measuring the potential difference between a hydrogen electrode and a standard electrode. An example of a standard electrode is chloride

pH uses

PH is used in everyday life as well as in science and industry. It is used in cooking (for example, reacting baking powder and an acid to cook well), to design cocktails, cleaners and for food preservation.

It is important in pool maintenance and water purification, agriculture, medicine, chemistry, engineering, oceanography, biology and other sciences.

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