Question

when 100 grams of impure in limestone is heated the amount of Residue left is 50.4 grams calculate the percentage of purity of limestone​

Answer 1

Given info : when 100 grams of impure in limestone is heated the amount of Residue left is 50.4 grams.

To find : The percentage of purity of limestone is..

solution : we know, when limestone is heated it produces calcium oxide and carbon dioxide gas.

i.e., CaCO₃ ⇒CaO + CO₂ (↑)

we see, one mole of limestone evolves 1 mole of CO2 and 1 mole of CaO remains in the reaction.

means, when 100g of pure limestone is heated, the amount of residual left is 56 g (44g of CO2 gas escape out from the reaction)

here mass of impure limestone = 100g

mass of residual left = 50.4 g

so percentage of purity of limestone = mass of residual left in impure limestone/mass of residual left in pure limestone × 100

= 50.4/56 × 100

= 90%

Therefore the percentage of purity of limestone is 90%