Question

Calculate the mass percent of each element in the molecule of calcium carbonate

2. Verify by calculating that

5 moles of CO₂ and 5 moles of H₂ 0 do not have same mass.

240 g of calcium and 240 g of magnesium elements have a mole ratio of 3:5.

Answer 1

1.molar mass of CaCO₃ = 40 + 12 + 48 = 100
Mass % of Ca = 40/100*100 = 40%
mass % of C = 12/100 * 100= 12 %
Mass % of O = 48/100 *100 =48%

2. Number of mole =Given mass/ molecular mass
Given mass of CO₂ = number of moles of CO₂* Molecular mass of CO₂
= 5 * 44 = 220 g
Given mass of H₂O = number of moles of H₂O *Molecular mass of H₂O
= 5 * 18 =90g
5 moles of CO₂ = 220g
5 Moles of H₂O = 90g

3. Number of moles of Mg = given mass /atomic mass of Mg = 240/24 = 10 moles
Number of moles of Ca = given mass /atomic mass of Ca = 240/40 = 6 moles
Molar ratio of Ca: Mg = 6 : 10 = 3 : 5