write a note on acid , bases and salts 150-200 worlds (class 10 ) (science lesson )
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Answer:
Experimental Definitions
Earlier, acids, bases, and salts were characterized by the experimental testing of their aqueous solutions. An acid is defined as a substance whose water solution tastes sour, turns blue litmus red and neutralizes bases. A substance is called base if its aqueous solution tastes bitter, turns red litmus blue or neutralizes acids.
Acids
Salt is a neutral substance whose aqueous solution does not affect litmus. According to Faraday: acids, bases, and salts are termed as electrolytes. Further, Liebig proposed that acids are compounds which contain hydrogen that can be replaced by metals.
Acids
Acidity is a characteristic property of acids. Acidic substances are usually very sour. Apart from hydrochloric acid, there are many other types of acids around us. Citrus fruits like lemons and oranges contain citric and ascorbic acids while tamarind paste contains tartaric acid.
In fact, the word ‘acid’ and ‘acidity’ are derived from the Latin word ‘acidus’ which means sour. If you dip a blue litmus paper into an acid, it will turn red while a red litmus paper will not change colour. Acids also liberate dihydrogen when they react with some metals.
Bases
Bases turn red litmus paper blue while the blue litmus paper stays blue. They taste bitter and also feel soapy. Some other common examples of bases include sodium bicarbonate that is used in cooking and household bleach.
acidity
Image: Litmus paper test. [Source: Wikimedia Commons]
Salts
Apart from sodium chloride, other common salts are sodium nitrate, barium sulfate etc. Sodium chloride or common salt is a product of the reaction between the hydrochloric acid (acid) and sodium hydroxide (base). Solid sodium chloride is made of a cluster of positively charged sodium ions and negatively charged chloride ions held together by electrostatic forces.
Electrostatic forces between opposite charges are inversely proportional to the dielectric constant of the medium. In other words, we can say that a compound that has acidity in its nature and a compound that has basicity as its nature, may yield salts when combined together.
The universal solvent, water, has a dielectric constant of 80. Therefore, when sodium chloride is dissolved in water, the dielectric constant of water reduces the electrostatic force, allowing the ions to move freely in the solution. They are also well-separated due to hydration with water molecules.
acidity
Explanation: