Q.

The amount of calcium oxide produced on heating 150 kg limestone (75% pure) is _____ kg.

(Nearest integer)

Given: Molar mass (in g mol-1) of Ca–40, O–16, C–12                        [2025]


Ans.

(63)

Mass of CaCO3 in 150 kg sample of limestone (WCaCO3)=75% of 150 kg=0.75×150 kg=112.5 kg=112500 g

Molar mass of CaCO3 (MCaCO3)=100 g/mol

Moles of CaCO3 (nCaCO3)=WCaCO3MCaCO3

=112500100=1125 mol

Decomposition of calcium carbonate is represented as:

CaCO3(s)→ΔCaO(s)+CO2(g)

By stoichiometry, 

nCaO=nCaCO3=1125 mol

Mass of CaO=nCaO×MCaO=1125×56 g=63000 g=63 kg