ACID BASES AND SALTS
NAZLI ILHAN X-A
Acids: Acids are sour in taste, turn blue litmus red, and dissolve in water to release H+ ions. Example: Sulphuric acid (H2SO4), Acetic Acid (CH3COOH), Nitric Acid (HNO3) etc. Properties of Acids: Acids have a sour taste.Turns blue litmus red.Acid solution conducts electricity.Release H+ ions in aqueous solution. Types of Acids: Acids are divided into two types on the basis of their occurrence i.e., Natural acids and Mineral acids. (i) Natural Acids: Acids which are obtained from natural sources are called Natural Acids or Organic Acids. Examples: Methanoic acid (HCOOH) Acetic acid (CH3COOH) Oxalic acid (C2H2O4) etc.
Acids Strong Acids An acid which is completely ionised in water and produces (H+) is called Strong Acid. Examples: Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid (HNO3) Weak Acids An acid which is partially ionised in water and thus produces a small amount of hydrogen ions (H+) is called a Weak Acid. Example: Acetic acid (CH3COOH), Carbonic acid (H2CO3)
Bases: Bases are bitter in taste, have soapy touch, turn red litmus blue and give hydroxide ions (OH–) in aqueous solution. Examples: Sodium hydroxide (caustic soda) – NaOH Calcium hydroxide – Ca(OH)2 Potassium hydroxide (caustic potash) – (KOH) Properties of Bases: Have a bitter taste.Soapy to touch.Turns red litmus blue.Conducts electricity in solution.Release OH– ions in Aqueous Solution Types of bases: Bases can be divided in two types – Water soluble and Water-insoluble. The hydroxide of alkali and alkaline earth metals are soluble in water. These are also known as alkali. For example; sodium hydroxide, magnesium hydroxide, calcium hydroxide, etc. Alkali is considered a strong base.
Hydrochloric acid (HCl) Sulphuric acid (H2SO4) Nitric acid (HNO3) Bases Sodium hydroxide (NaOH) Potassium hydroxide (KOH) Calcium hydroxide (Ca(OH)2) Difference between a base and an alkali Base: Bases undergo neutralisation reaction with acids.They are comprised of metal oxides, metal hydroxides, metal carbonates and metal bicarbonates.Most of them are insoluble in water. Alkali: An alkali is an aqueous solution of a base, (mainly metallic hydroxides).It dissolves in water and dissociates to give OH− ion.All alkalis are bases, but not all bases are alkalis. To know more Difference between a base and an alkali,
Hydronium ion is formed when a hydrogen ion accepts a lone pair of electrons from the oxygen atom of a water molecule, forming a coordinate covalent bond.
Dilution Dilution is the process of reducing the concentration of a solution by adding more solvent (usually water) to it. It is a highly exothermic process. To dilute acid, the acid must be added to water and not the other way round. Strength of acids and bases Strong acid or base: When all molecules of a given amount of an acid or a base dissociate completely in water to furnish their respective ions, H+(aq) for acid and OH−(aq) for base). Weak acid or base: When only a few of the molecules of a given amount of an acid or a base dissociate in water to furnish their respective ions, H+(aq) for acid and OH−(aq) for base).
Baking Soda (NaHCO3): Baking soda is another important product which can be obtained using byproducts of chlor – alkali process. The chemical name of baking soda is sodium hydrogen carbonate (NaHCO3) or sodium bicarbonate. Bread soda, cooking soda, bicarbonate of soda, sodium bicarb, bicarb of soda or simply bicarb, etc. are some other names of baking soda. Preparation Method: Baking soda is obtained by the reaction of brine with carbon dioxide and ammonia. This is known as Solvay process
In this process, calcium carbonate is used as the source of CO2 and the resultant calcium oxide is used to recover ammonia from ammonium chloride. Properties of Sodium Bicarbonate: Sodium bicarbonate is white crystalline solid, but it appears as fine powder.Sodium hydrogen carbonate is amphoteric in nature.Sodium hydrogen carbonate is sparingly soluble in water.Thermal decomposition of sodium hydrogen carbonate (baking soda).When baking soda is heated, it decomposes into sodium carbonate, carbon dioxide and water. 2NaHCO3 + heat → Na2CO3 + CO2 + H2OSodium carbonate formed after thermal decomposition of sodium hydrogen carbonate decomposes into sodium oxide and carbon dioxide on further heating. Na2CO3 → Na2O + CO2 This reaction is known as Dehydration reaction.
Use of Baking Soda:
Baking soda is used in making of baking powder, which is used in cooking as it produces carbon dioxide which makes the batter soft and spongy.Baking soda is used as an antacid.Baking soda is used in toothpaste which makes the teeth white and plaque free.Baking soda is used in cleansing of ornaments made of silver.Since sodium hydrogen carbonate gives carbon dioxide and sodium oxide on strong heating, thus, it, is used as a fire extinguisher
Baking Powder: Baking powder produces carbon dioxide on heating, so it is used in cooking to make the batter spongy. Although, baking soda also produces carbon dioxide on heating, but it is not used in cooking because on heating, baking soda produces sodium carbonate along with carbon dioxide. The sodium carbonate, thus, produced, makes the taste bitter.
Baking powder is the mixture of baking soda and a mild edible acid. Generally, tartaric acid is mixed with baking soda to make baking powder.
Washing Soda (Sodium Carbonate) Preparation Method: Sodium carbonate is manufactured by the thermal decomposition of sodium hydrogen carbonate obtained by Solvay process.
The sodium carbonate obtained in this process is dry. It is called Soda ash or Anhydrous sodium carbonate. Washing soda is obtained by rehydration of anhydrous sodium carbonate.
Since there are 10 water molecules in washing soda, hence, it is known as Sodium Bicarbonate Decahydrate. Sodium carbonate is a crystalline solid and it is soluble in water when most of the carbonates are insoluble in water. Use of sodium carbonate: It is used in the cleaning of cloths, especially in rural areas.In the making of detergent cake and powder.In removing the permanent hardness of water.It is used in glass and paper industries.
CHEMISTRY ACID BASES AND SALTS SUBMITTED BY:NAZLI ILHAN SUBMITING TO:MANJU MISS CLASS:X-A