Acids, Base, Salts

4 min read

Acids

Acid rain

Base

Indicators

Litmus - a natural dye

  • blue litmus paper - base
  • red litmus paper - acid

Turmeric

China Rose

Phenolphthalein

Neutralisation

  • Acid + Base –> Salt + water + heat

Digestion

Ant bite

Soil treatment

Factory wastes

Class 7 Arjun

Acids

  • latin word - 'acere' - sour
  • Tamarind - tartaric acids
  • vinegar - acetic acid
  • lemon, orange - citric acid,
  • apples - maleic acids
  • unripe mangoes - tartaric acids
  • milk, curd - lactic acid
    • when lactic acids gets accumulated in our muscles, it leads to cramps
  • grapes - tartaric acids
  • ant sting - formic acids
  • tea - tannic acids
  • amla, citrus fruits - ascorbic acids (vitamin C)
  • spinach, tomatoes - oxalic acids
  • protein - amino acids
  • coffee - chlorogenic acids
  • stomach - hydrochloric acids - protected by mucus lining

Types

  • organic or naturally occurring - present in plants and animals
  • mineral acids - derived from minerals - corrosive in nature - burn the skin and flesh
    • sulphuric acids - H2SO4 - strong - King of chemicals because of its widespread use
      • Manufacturing Fertilizers: It is extensively used in the production of phosphate fertilizers such as superphosphate and ammonium sulfate.
      • Petroleum Refining: Sulfuric acid is used in the refining process to remove impurities, such as water and sulfur compounds, from crude oil.
      • Chemical Synthesis: It acts as a catalyst and reactant in the production of many chemicals, including hydrochloric acid, nitric acid, synthetic detergents, dyes, pigments, and explosives.
      • Metallurgy: Used in the extraction and refining of metals, including copper, zinc, and uranium. It is also employed in steel pickling to remove rust and scale.
      • Battery Acid: Sulfuric acid is the electrolyte in lead-acid batteries commonly found in automobiles.
      • Water Treatment: It is used to neutralize water and remove impurities such as bacteria, algae, and unwanted minerals.
      • Cleaning Agents: Strong sulfuric acid is used in industrial cleaning agents for removing tough deposits like grease and oil from equipment.
      • Pharmaceuticals: It is used in the synthesis of many pharmaceutical products and intermediates.
      • Textile and Dye Industry: Sulfuric acid is used in textile processing and in the manufacture of dyes and pigments.
      • Paper and Pulp Industry: It is involved in the processing of wood pulp to produce paper and cellulose products.
    • hydrochloric acids - HCl - strong
    • nitric acid - HNO3 - strong
    • phosphoric acids - H3PO4 - strong

Use of mineral acids

  • manufacturing of fertilisers, chemical dyes, explosives, detergents, plastics

Strong and Weak acids

  • mineral acids mostly are strong
  • organic acids mostly are weak
  • Ex: weak acids - carbonic acids in drinks

Acid Rain

  • CO2CO_2 and NO2NO_2 and SO2SO_2 gets converted into its acids in the atmosphere due to reaction with water
  • comes down with rain
  • destroys monuments, buildings, lakes, plants, living beings

Base

  • slippery or soapy
  • bitter taste
  • manufacture of soaps, detergents, bleaching powder, fertilisers, softening of hard water
  • MgOH2 - magnesium hydroxide - milk of magnesia
  • NH4OH - ammonium hydroxide - window cleaner
  • CaOH - calcium hydroxide - limewater
  • sodium or potassium hydroxide - K / NaOH - soap

Strong - Weak Base

  • lime water - strong - prepared by mixing chuna in water - used as laboratory reagent - also used for whitewashing when diluted making it weak base
  • ammonium hydroxide - weak base - used in manufacture of fertilisers
  • sodium or potassium hydroxide - strong
  • magnesium hydroxide , ammonium hydroxide - weak

Indicators

  • to tests the acids or bases
  • Natural and artificial indicators

Natural

  • Litmus - extracted from lichens - purple or mauve in colour in distilled water - red in acids and blue in basic - red and blue litmus paper
  • Turmeric - yellow in colour - made by colouring a blotting paper and mixed with water, forms turmeric paste - no colour change in acids but red in basic - tests for base only - no colour change in neutral solutions
  • China rose - hibiscus - light pink or light red colour when prepared - dark pink or magenta in acids - green in basic
  • Purple cabbage juice - red in acids and green in basic
  • Red cabbage juice, violets primroses, cherries, beetroots, grape juice, any flower with red, blue, purple colour contain chemicals act as indicators

Synthetic Indicators

  • Phenolphthalein - used in neutralisation reaction - to indicate the completion of the reaction - pink colour in base and colourless in acids and neutral
  • Methyl orange - yellow in neutral and basic and red in acids
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