Acids, Bases, and Neutralisation Reactions

Acids  

- Compounds that release positive hydrogen ions (H⁺) in aqueous solution.  

- They taste sour and can turn blue litmus paper red.  

Bases  

- Substances that, when dissolved in water, release hydroxide ions (OH⁻) into the solution.  

- They taste bitter, feel soapy, and turn red litmus paper blue.  

Neutralisation Reaction  

- When an acid reacts with a base, it forms a salt and water.  

- This reaction helps neutralise the effects of both substances.  

  Acid + Base --> Salt + Water  

Salt  

- A compound produced by neutralisation when an acid and a base react together.  

- Common examples: Sodium chloride (NaCl), Potassium nitrate (KNO₃).  

Phenolphthalein  

- A colourless crystalline solid used as an indicator.  

- Turns pink in alkaline solutions and remains colourless in acidic solutions.  

Types of Acids  

- Organic Acids: Found in plants and animal products (e.g., citric acid in lemon, lactic acid in curd).  

- Mineral Acids: Obtained from minerals in the Earth’s crust (e.g., hydrochloric acid, sulphuric acid, nitric acid).  

Strength of Acids  

- Weak Acids: Partially dissociate in water, releasing fewer hydrogen ions (e.g., acetic acid, citric acid).  

- Strong Acids: Completely dissociate in water, releasing more hydrogen ions (e.g., HCl, H₂SO₄, HNO₃).  

Common Terms and Applications  

- Granulated: Refers to substances in small grain‑like form (e.g., granulated sugar or salt).  

- Splinter: A thin, sharp piece of material, often used to describe fragments of wood or glass.  

- Effervescence: The bubbling or fizzing observed when a gas (usually CO₂) is released during a chemical reaction.  

- Automobile Battery: Contains sulphuric acid, which acts as an electrolyte to generate electrical energy.  

- Preservatives: Often contain weak organic acids (like benzoic acid or citric acid) to prevent food spoilage.  

- Milk of Magnesia: A mild base (magnesium hydroxide) used to neutralise excess stomach acid and relieve indigestion.  

- Alkali Metals: Group 1 elements (e.g., sodium, potassium, lithium) that form strong bases when combined with water.  

Insight:  

Acids and bases are fundamental to chemistry and daily life, from digestion and cleaning to industrial processes and medicine. Their balance through neutralisation keeps both biological and chemical systems stable.