Question

What amount of CO2 is obtained if 200 g of 40% CaCO3 on heating ?

Answer 1

CaCO3 -> CaO + CO2

firstly, calculate the relative formula mass of CaCO3 and CO2.

RFM of CaCO3 = 40 g + 12 g + (16 g x 3) = 100 g

RFM of CO2 = 12 g + (16 g x 2) = 44 g

the decomposition equation shows 1 CaCO3 goes to 1 CaO and 1 CO2.

we have 50 g of CaCO3, effectively we have half a CaCO3.

50 g / 100 g = 0.5

in order to get the mass of CO2 we need to times the RFM of CO2 by 0.5 (or divide by 2) because of the ratio of CaCO3 to CO2:

44 g x 0.5 = 22 g

22 g of CO2 is obtained from decomposition of 50 g of CaCO3.

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