Students must go through these JAC Class 10 Science Notes Chapter 2 Acids, Bases and Salts to get a clear insight into all the important concepts.
JAC Board Class 10 Science Notes Chapter 2 Acids, Bases and Salts
→ Acid: Acids are sour in taste. Acid turns wet blue litmus paper to red. It releases H+ ions in an aqueous solution. Acid has a pH value lower than 7. H+(aq) ions in the solution are responsible for acidic character.
→ Base: Bases are bitter in taste. Base turns wet red litmus paper to blue. It releases OH– ions in an aqueous solution. Base has a pH value higher than 7. OH–(aq) ions in the solution are responsible for basic character.
→ Indicator: Indicator changes colour in presence of acid or base or it changes odour (smell) in presence of acid or base.
- Synthetic indicators : Methyl orange and Phenolphthalein.
- Natural indicators : Extract of red cabbage leaves, turmeric, vanilla extract, onion, starch.
→ On reaction with metal, acid liberates dihydrogen (H2) gas and forms corresponding salt, while, base reacts with active metal to form dihydrogen gas and a salt is formed which has a negative ion (anion) consisting of metal and oxygen.
→ Acid reacts with metal carbonate, or metal hydrogen carbonate and forms the corresponding salt, carbon dioxide gas and water.
→ Aqueous solutions (solutions prepared in water) of acids and bases conduct electricity because they produce hydrogen ions (H+(aq)) and hydroxide ions (OH–(aq)) responsible for conducting electricity.
→ pH scale: pH scale is useful to determine the nature of the solution whether acidic or basic.
- For acidic solution : pH < 7, pOH > 7
- For basic solution : pH > 7, pOH < 7
- For neutral solution : pH = 7, pOH = 7
→ Most of the metabolic reactions taking place in living bodies are within a narrow pH range of 7.0 to 7.8.
→ Mixing of a concentrated acid or a base with water is a highly exothermic reaction.
→ Neutralisation reaction: The chemical reaction in which acid and base neutralise each otiier to form corresponding salt and water is called neutralisation reaction. Salts have various uses in daily life and in industries.
→ Substance (Compound) and its uses:
- Vanilla, onion, clove : As olfactory indicator
- Milk of magnesia : As an antacid
- Sodium chloride (NaCl) : In the preparation of sodium hydroxide, baking soda, washing soda, bleaching powder and in various substances used in daily life.
- Sodium hydroxide (NaOH) : For making soaps, detergent, in purification of petroleum, in laboratory.
- Bleaching powder (CaOCl2) : Used as bleaching agent, as disinfectant and as an oxidising agent.
- Baking soda (NaHCO3): Used as an antacid, as disinfectant, in laboratory, making food soft and spongy and used in soda-acid fire-extinguishers.
- Washing soda (Na2CO3) : Used in making glass, soaps, as cleansing agents for domestic purposes, in paper and textile industries and in laboratory.
- Plaster of paris (CaSO4.\(\frac { 1 }{ 2 }\)H2O) : Used in construction industry, as plaster for supporting fractured bones, chalk for blackboard, making toys, in decoration material, making moulds and in laboratory.