Advantages & Disadvantages Of Litmus Paper

Litmus paper is chemically dyed paper used to determine the pH of the liquid that it is being dipped into. The paper turns blue for a liquid with a pH greater than 8 and red for a liquid with a pH less than 5. Acids turn blue litmus paper red while bases turn red litmus paper blue.

Types of Litmus Paper

There are two types of litmus paper: red and blue. The color is obtained from organic dye used to dye the paper. Compounds are tested for their alkaline content with red litmus paper. Red litmus paper turns blue in the presence of a base. The acidity of a compound is determined with the use of blue litmus paper. Blue litmus paper turns red when dipped into an acid. Blue litmus paper does not change color in the presence of a base, and red litmus paper does not change color in the presence of an acid.

Advantages of Litmus Paper

Litmus paper can be obtained fairly inexpensively and used to distinguish between acids and bases. It can be used to test both liquid and gaseous molecules. It is frequently used to approximate the acidity levels of household chemicals and rain water. Litmus paper can also be used for anion or negative ion testing. As an example, when ammonia is added to a known phosphate solution, it becomes basic. This can be tested with red litmus paper.

Disadvantages of Litmus Paper

Litmus paper does not provide detailed information about the strength or type of the acid or base being tested. It provides only the basic identification information. In comparison, other commercial pH papers provide a range of colors and more specific information about the pH of the compound. A pH meter provides an accurate pH reading. Litmus paper should be used only for rough estimates.

Sources of Influence on pH

The pH of substances like rainwater can change throughout the day. Carbon dioxide acts as carbonic acid in water and causes rainwater to be acidic. Increases in carbon dioxide levels change the acidity of rainwater. Different types of pollution also affect the pH levels organic compounds in different geographic locations. Litmus paper can be used to ascertain the influence of changing environmental conditions on different compounds.

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