#9thchemistrychapter7 #Acidandbasechemistry

TEXT BOOK PAGE NUMBER: 93 and 94 Note: In this video the wordings are same as in the text book. Write Headings on your book. Notes are in description. 7.1 Acids and Bases • Acids and bases have been known to mankind since centuries.  Acids • Acids have been known for their sour taste like the taste of lemon and ability to change the colour of litmus paper from blue to red. • There are many substances which contain acids and hence taste sour, such as curd, tamarind, lemon and lime, etc. • Common examples of acids include acetic acid, hydrochloric acid, nitric acid, sulphuric acid and tartaric acid. • Most of these acids, we come across in everyday life, are available in the form of aqueous solutions as they can be easily dissolved in water. Types of Acids • Acids are divided into two types on the basis of their occurrence: natural acids and mineral acids. 1. Organic acids: Acids which are obtained from natural sources are called natural or organic acids. 2. Mineral or man-made acids: are prepared from minerals like sodium chloride or sodium nitrate. Common examples of mineral acids are hydrochloric acid, sulphuric acid and nitric acid. Table (7.1) Some Common Organic Acids and their Sources Organic acid - Natural Source • Acetic acid - Vinegar • Ascorbic acid - Amla, Guava • Citric acid - Lemon, Orange • Lactic acid - Sour milk, Curd • Formic acid - Ant sting • Oxalic acid - Tomato • Tartaric acid - Tamarind  Bases • In comparison to acids, bases are known for their bitter taste, slippery touch and ability to change the colour of litmus paper from red to blue. • An alkali is a base that dissolves in water. • Some common examples of alkalis are sodium hydroxide (caustic soda), potassium hydroxide (caustic potash), calcium hydroxide (lime water) and aqueous ammonia (NH₄OH). • Both sodium hydroxide and potassium hydroxide are extremely corrosive and can burn your skin.  Metal Oxides • Metal oxides are also basic in nature because they react with acids to form salts and water. • Na₂O is basic oxide because it contains oxide ion, O²⁻, which is a very strong base with a strong tendency to react with water to produce hydroxide ions. Na₂O (s) + H₂O (l) → 2NaOH (aq) • Other examples of basic oxides are calcium oxide (CaO), zinc oxide (ZnO) and magnesium oxide (MgO).  Neutralization Reaction • Both acids and bases are known to cancel the properties of each other when mixed together in equal amounts. • The reaction is called neutralization reaction. • A salt and water are formed as a result of this reaction. #acids #bases #conceptsofacidsandbases #arrheniusconceptofacidandbase #bronstedlowryconceptsofacidsandbases #interestinginformation #exercise #propertiesofacidsandbases #acidrainanditseffects #keypoints #exercisemcqs #exercisequestionsforshortanswers #exerciseconstructedresponsequestions #exercisedescriptivequestions #exerciseinvestigativequestions #9thchemistryplaylistchapter7 #playlistchapter7chemistry9th #9thclassonlinechemistry