Question

Calculate the mass of CO2 produced by heating 40g of 20% pure limestone

Answer 1

CaCO3 decomposition:
CaCO3 -> CaO + CO2
The first thing to do here is to 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 are obtained from decomposition of 50 g of CaCO3.
by do like this method

Answer 2

Reaction of CaCO3 -> CaO + CO2

The decomposition equation shows 1 CaCO3 gives 1 CaO and 1 CO2.

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


Mass of CO2 = 12 g + (16 g x 2) = 44 g

So ,it is clear that 100g of caco3 gives 44g of co2.

We have 40g of 20% pure caco3

Mass of caco3 = 40×(20/100)

= 40/5 = 8g

Co2 obtained from 8 g of caco3 = 8×(44/100)

= (352/100) g

= 3.52 g


Hope it helps