pH Scale
The pH of a solution is defined as the measure of the H+ ions concentration present in the given solution. This is a short note on pH scale and how it is measured.
Summary
The pH of a solution is defined as the measure of the H+ ions concentration present in the given solution. This is a short note on pH scale and how it is measured.
Things to Remember
- The pH of a solution is defined as the measure of the H+ ions concentration present in the given solution.
- The pH value of a solution can be found out by using universal indicator and pH colour chart and pH meter.
- The pH scale is a standard scale, which is used for measuring the approximate strength of an acid or an alkali solution.
- pH meter is a man made instrument which is used for measuring the pH value of a given solution directly in the numbers.
- pH value helps to understand the nature of the solutions and to compare acidity and alkalinity of the solution.
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pH Scale
The pH of a solution is defined as the measure of the H+ ions concentration present in the given solution. pH stands for potentiality of hydrogen. The higher the H+ ions in the solution, the more is the acidic solution whereas the higher the OH-ions in the solution, the more is the alkaline solution.
The pH value of a solution can be found out by the following two ways:
- By using universal indicator and pH colour chart
- By using pH meter
By using universal indicator and pH colour chart
The pH scale is a standard scale, which is used for measuring the approximate strength of an acid or an alkali solution.
The pH scale has ranged from 1 to 14. Acidic solutions have a pH value less than 7, while alkaline solutions have a pH value greater than 7. Distilled water has pH value 7 and is called neutral substance. Strong acids have pH value 1 or 2 while strong alkalis have pH value 13 or 14.
From the pH scale, we can say that higher the hydrogen ion concentration, lower is the pH value and vice versa.
The pH values of some substances are as follows:
| S.N | Substances | pH |
| 1.) | Hydrochloric acid | 1 |
| 2.) | Apple, Vinegar and Carbonic acid | 3 |
| 3.) | Copper sulphate solution | 5.5 |
| 4.) | Water | 7 |
| 5.) | Human Blood | 7.3 |
| 6.) | Ammonia solution (NH4OH) | 10 |
| 7.) | Sodium Hydroxide (NaOH) | 13 |
By using pH meter
pH meter is a man-made instrument which is used for measuring the pH value of a given solution directly in the numbers.
A solution of which pH value has to be measured is taken in a beaker and the pH rod is dipped in it. When the switch is on, the indicator of the pH meter deflects from its position and shows the pH value of the given solution.
Differences between pH paper and pH meter| It is strip of paper. | It is a man made instrument. |
| It measures pH when dipped in a solution. | It measures pH directly on a meter. |
Importance of pH value
- pH value helps to understand the nature of solutions.
- It is used to find the pH value of soil condition in farming.
- It is used to know the pH value of water before water is supplied.
- It helps to compare acidity and alkalinity of solution.
Lesson
Acid Base And Salt
Subject
Science
Grade
Grade 10
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