Let % of CaCO3 be x and we take 100 gm of clay then,
Mass of SiO2=85−x
After heating SiO2 is 51.5% and CaO is 41.2% as moisture is 7.3%
Since the mass of SiO2 will remain same, then
51.5100 × weight of the clay after heating = 85−x∴ weight of the clay after heating = (85−x)10051.5.
So, mass of the CaO
=(85−x)10051.5×(41.2100) ---- (1)
Since CaCO3 is completely converted to CaO, the number of moles of CaO and CaCO3 are the same.
So mass of CaO will be x100×56 ----(2)
From equations (1) and (2),
⟹(85−x)10051.5×(41.2100)=x100×56
⟹x=50 gm