Element | Symbol | Valency | Hydrogen | H | 1 | Oxygen | O | -2 | Carbon | C | 4 | Calcium | Ca | 2 | Iron | Fe | 2 | Aluminium | Al | 3 | Sodium | Na | 1 | Potassium | K | 1 | Magnesium | Mg | 2 | Zinc | Zn | 2 | Copper | Cu | 2 | Silver | Ag | 1 | Lead | Pb | 2 | Chloride | Cl | -1 | Sulphate | SO4 | -2 | Hydroxide | OH | -1 | Carbonate | CO3 | -2 | Nitrate | NO3 | -2 | Phosphate | PO4 | -3 | Hydrogen Carbonate | HCO3 | -1 |
Acids and Bases in the Laboratory
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Some common acids that are found in laboratories are Hydrochloric acid (HCl), Sulphuric acid (H2SO4) and Nitric acid (HNO3). Some of the lesser used acids are Acetic acid (CH3COOH), Hydrofluoric acid (HF), Carbonic acid (H2CO3). Hydrofluoric acid is a highly corrosive acid and is used to etch glass. Some acids are found in nature, like citric acid in certain fruits. These acids are called 'organic acids'.
Examples are: * Citric acid (from citrus fruits and vegetables,) * Ascorbic acid (vitamin C, as from certain fruits) * Acetic acid (Vinegar) * Lactic acid (in buttermilk) * Tartaric acid (Tamarind) * Oxalic acid (Tomatoes) Commonly found bases in laboratories and in our daily life are: Caustic soda, NaOH; Caustic potash, KOH; Milk of magnesia, Mg(OH)2; Liquor ammonia, NH3; Washing powder, Tooth paste.
One can familiarize with the acid base nature of some of the common substances by using litmus solution.
Activity : Make solutions of the following substances:
'Borax', 'Blood', 'Milk', 'caustic soda', 'Lemon Juice', 'Bleaching powder', 'Tomatoes', 'Vinegar', 'detergent', 'Pure
Water', 'Coffee', Baking Soda'.
Put a drop of each of the above solutions on a watch-glass and test by adding a drop of litmus to it.
Answer : Lemon juice, vinegar, tomatoes, coffee