pH is a one kind of measurement technique to identify the acidic or basic characteristics of selected solution. The hydrogen ion concentration can be measured easily by this technique. The values of pH scale ranges from 0 to 14. An aqueous solution which contains pH less than 7 is acidic, while a basic solution contains more than 7 at 25°C. The acidity or basicity characteristic of a solution is identified by calculating the value of this factor.
pH Definition in Chemistry
It represents the negative logarithm to the base 10 of H+ ion concentration in an aqueous solution. Actually, it expresses the power of hydrogen in a tested solution. It measures the acidity or alkalinity of selected solutions. It can be expressed as,
pH = -log [H+]
It is a quantitative measurement of aqueous solution for identifying its acidity or basicity. The value of pH ranges between 0-14 for an aqueous solution, where the lowest value on this scale is 0 and considered to be more acidic and range 14 is considered to be the most basic in nature.
From the above equation, it can be understood that if a solution contains a pH scale of 4 this will mean that it is 10 times more acidic than the pH scale of 5. The reason behind that, each range on a pH scale shows various values from the each other with a factor of 10.
Characteristics
It expresses the power of hydrogen in aqueous solution.
It shows the acidity or basicity of tested solution.
It is a quantitative measurement for identified solution.
It expresses the hydrogen ions in solution.
It is used to determine the quantitative strength of acids and bases.
The acidic solution has its value below 7, while basic solution has its value more than 7.
The neutral solution has its value 7.
History
This technique was discovered in 1909 by Danish biochemist S.P.L. Sørensen at the Carlsberg Laboratory in Copenhagen. It had the ability to measure acidic or basic characteristic of solution. The concept from Sørensen was later revised in 1924 to make the modern pH measurements in terms of electrochemical cells. pH expresses the “power of hydrogen ion.” This word comes from the German word “potenz,” which means “power.”
Equation
The equation for this matter was firstly introduced by Danish biochemist Soren Peter Lauritz Sorensen which equation is given below:
pH= -log10 [H+]
Where, log = base- 10 logarithm
[H+] = hydrogen ion concentration (moles per litre)
Where, log is the base-10 logarithm and [H+] stands for the hydrogen ion concentration in units of moles per liter solution.
Examples
We test and work with various chemicals in our everyday life. Some pH values of various chemicals are given below:
The pH values of hydrochloric acid, lemon juice, vinegar, pure water, human blood, soapy water, lye, sodium hydroxide is 0, 2, 2.2, 7, 7.4, 12, 13, and 14 respectively.
Importance
It is very essential to know the definite value of hydrogen ion or hydroxyl ion in certain reaction because hydrogen ion or OH– acts the main reactant factor to run the reactions. The biochemical reactions depend the specific hydrogen ions or hydroxyl ions values. The working mechanism of our ecosystem and human body activities require definite hydrogen ions or hydroxyl ions values.
Uses
The measurements and controlling this value is important to use in our everyday life. It is mostly used in food preservation purposes and food items preparation purposes. It is very important to maintain this value for water of swimming pools and in water purification, agriculture, fertilizer, medicine, chemistry, engineering, etc. It is an important value for human life because human blood contains a definite value of hydrogen ion concentration.
Measurement Technique
The value of this factor can be measured by using litmus paper or another type of paper. This technique is simple and quick measurement way. At present, pH meter is used to calculate this value properly. This meter has the ability to measure the potential difference between a hydrogen electrode and a standard electrode to measure the value of pH in simple, stained or turbid samples.
pH paper
This paper is used to measure the values of hydrogen or hydroxyl ion concentration in solutions. Flavin chemical is treated with this paper which is completely soluble in water and changes color in the presence of various types of solutions. The color of this paper turns into red in acidic solution and greenish blue color in alkaline solutions.
Light green color is found when it immersed into a neutral solution. Flavin chemical indicator is the responsible to create this situation. We know that acidic solution contains higher hydrogen ions and alkaline solution contains higher hydroxide ion. Neutral solution contains equal amounts of hydrogen ions and hydroxide ions.
The chemical indicators which are coated on this paper are weak acids or weak bases that have the abilities to show color change at specific value of this factor. The proton transfer mechanism in acidic or basic solution is responsible to changes color of this paper in the solution.
This paper is very much used to know the values of hydrogen ion presence in soil samples. The values of hydrogen ions or hydroxide ions concentration can be determined by this paper. It is very important to know the acidic, basic or neutral character of the solution in laboratory. The hydrogen ion concentration values of various biological fluids like urine, blood, etc. can be determined by helping this paper.
This paper is widely used to know the hydrogen ion concentration of municipal drinking water, swimming pools, and rainwater. This paper is used in pharmaceutical manufacturing, ETP plant, biotechnology, and petroleum based chemical industries.
pH Meter
It is an electrical analytical device which is very effective to calculate the acidity or alkalinity of liquids and semi-solids. The working activities of this meter depend on the ion exchange characteristic of the sample solution which is tested to the inner solution of the glass electrode via the glass membrane.
The probe of this meter which is immersed into solution shows the value of hydrogen ion in the solution. The sensor of this meter contains a porous glass membrane which coated with metal salts and silica. The probe of this meter must be submerged in a sample solution for measuring the hydrogen ion concentration.
This meter is widely used to neutralize wastewater from the iron, pharmaceutical, paper, biotech, chemical, fertilizer and petrochemical industries. It is important to keep this meter for monitoring the level of pH in water purifier. It has various uses in food industry for food safety issues. It is as essential tool in diagnostic center to measure the biological conditions in blood, urine, gastric acid, etc.
pH Calculations
The calculation of this matter depends on the following formula:
pH = -log10[H+]
[H+] = 10-pH
Some examples are given below:
Frequently Asked Questions (FAQs)
What is pH in chemistry?
It is the strength of hydrogen ion concentration in aqueous solution to select the acidic or basic characteristics of solution.
What is the full meaning of pH?
Its full meaning is potential of hydrogen which measures the concentration of hydrogen ions in a substance.
What is the formula of pH?
The formula equation of this matter is pH = -log10[H+].
What is pH paper?
It is coated with chemical indicator to express the acidic or basic characteristics of solution after dipping into the solution.
What is pH meter?
It is a device to use the identification of acidic or basic characteristics of solution after dipping the probe of this device into the solution.
