Chemical calculations

Chemical calculations

1. Percentage composition

   • %of C in CO2 = total relative mass of C in CO2 *100
   • relative molecular mass of CO2
   • Mr=12+(2*16)
   • Example-CO2
   • = 12/44*100= 12.3%
   • % of O in CO2 =
   • total relative mass of O in CO2
   • relative molecular mass of CO2
   • =32/44*100= 72.7%

2. Mass of reactants and products

   • Example-Na2CO3+2HLC------->H2O+CO2
   • Relative mass Sodium Carbonate=106
   • Relative molecular mass of carbon dioxide=44
   • 106g of Na2CO3 forms 44g of CO2
   • 1g of Na2CO3 forms 44/106 of CO2
   • 5.3g of Na CO3 forms 44/106*5.3 of CO2
   • = 2.2g

3. Yield of a chemical reaction