Question

2kg of CaCO3 decomposes completely on heating and forms CaO2. if 880 g ofCO2 is formed, what is mass of CaO formed​

Answer 1

The decomposition of CaCO3 is as follows:
    
 
        CaCO3(s) ---------> CaO(s) + CO2(g) 

     The mole ratio of the equation is 1:1:1....this 1 mole of CaCO3 yields 1 mole of CaO and 1 mole of CO2.

Calculate the moles of CaCO3:
moles = mass/molar mass
 moles = 5/100
    = 0.05 moles
This means that the moles of the CaO produced is also 0.05 moles since the mole ratio is 1:1:1

mass = moles × molar mass
         =  0.05 × 56
  2.8 grams 

Mass of CO2:
 mass = moles × molar mass

                  0.05 × 44
                  = 2.2 grams of CO2