Unit 1 - Chapter 2

Unit 1 - Chapter 2

1. Limestone & its Uses

   • Its Uses
     • Neutralising
     • Buildings
     • Toothpaste
     • Concrete
     • Glass
   • Calcium Carbonate: CaCO3
   • Found in the ground
   • A pale white-ish rock
   • Thermal Decomposition: When a substance is heated it will break down into simpler substances
     • Metal Carbonate --> Metal Oxide + Carbon dioxide
       • This happens with similar effects with all metals in group 2 e.g Magnesium Carbonate --> Magnesium Oxide + Carbon dioxide
     • CaCO3 --> CaO + CO2

2. Reactions of Carbonates

   • Limestone Statues are affected by acid rain
   • Testing for Carbon Dioxide
     • Limewater is a solution of Calcium Hydroxide. It is alkaline!
     • Carbon Dioxide is a weak acidic gas so it reacts with the Limewater.
     • Tiny particles of insoluble Calcium Carbonate are formed. This makes it look cloudy.
     • Limewater + Carbon Dioxide = Calcium Carbonate + Water
     • Ca(OH)2 + CO2 = CaCO3 + H2O
   • Carbonate + Acid = Salt + Water + Carbon Dioxide
   • Calcium Carbonate + Hydrochloric Acid = Calcium Chloride + Water + Carbon Dioxide
     • CaCO3 + 2HCl = CaCl2 + H2O + CO2

3. The Limestone Cycle

   • Step 2 is important - If we add water to Calcium Oxide we get limewater!
   • Nuetralizing Acids
     • Calcium Hydroxide is an alkali. It can neutralise acids to create calcium salt and water.
     • is used to neutralise soil and harmful acidic gases given of by factories.

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