Question

How many moles of MgSiO3 are in 207 g of the compound?

Answer 1

To get the number of moles we should divide the grams given by the substance's molar mass. The molar mass (M) of MgSiO₃ is 24.305 + 28.086 + 3x15.999 = 100.389 g/mol.
The amount of substance is n(MgSiO₃) = m(MgSiO₃)/M(MgSiO₃) = 207/100.389 = 2.062 mol

Answer: 2.062 mol