Calcium oxide is manufactured by heating calcium carbonate - Edexcel - GCSE Chemistry - Question 4 - 2013 - Paper 1

The balanced equation shows the conversion of calcium carbonate to calcium oxide and carbon dioxide:

$ext{CaCO}_3(s) → ext{CaO}(s) + ext{CO}_2(g)$

From the equation, 1 mole of CaCO₃ produces 1 mole of CaO. The molar mass calculation is:

• Calcium carbonate (CaCO₃):
  • Ca: 40
  • C: 12
  • O: 3 × 16 = 48

So,

$ext{Molar mass of CaCO}_3 = 40 + 12 + 48 = 100 ext{ g/mol}$

Now, to find the maximum mass of CaO from 25 tonnes (or 25000 kg) of CaCO₃:

• 1 tonne = 1000 kg, hence:

Mass of CaCO₃ = 25000 kg = 25000000 g

Using the molar ratio:

1 mole of CaCO₃ (100 g) gives 1 mole of CaO (56 g).

So:

ext{Maximum mass of CaO} = rac{56 ext{ g}}{100 ext{ g}} imes 25000000 ext{ g} = 14000000 ext{ g}

Converting to tonnes:

$14000000 ext{ g} = 14 ext{ tonnes}$

Thus, the maximum mass of calcium oxide that can be obtained is 14 tonnes.

Theoretical yield refers to the maximum amount of product that can be obtained from a chemical reaction based on the balanced equation. It is determined using the stoichiometry of the reaction, assuming that all reactants are completely converted to products without any losses.

The actual yield is often less than the theoretical yield due to several factors:

1. Reaction Incompleteness: The reaction may not go to completion, resulting in some reactants being left unreacted.
2. Loss of Product: Some product may be lost during the transfer, extraction, or purification process, reducing the overall yield.
3. Side Reactions: Other side reactions can occur, consuming reactants and producing alternative products, which can decrease the yield of the desired product.
4. Impurities: Impurities in the reactants may hinder the reaction or lead to unwanted byproducts.