Question

Calculate the number of moles in:

5 g of CaCO₃

Answer 1

Given: Weight of Calcium carbonate = 5 g

Step-1: Calculate the Gram molecular weight of Calcium carbonate (CaCO₃)

Gram atomic weight of Calcium (Ca)= 40 g mol^-1

Gram atomic weight of Carbon (C)= 12 g mol^-1

Gram atomic weight of Oxygen (O)= 16 g mol^-1

As Gram molecular weight is the sum total of the mass of all the atoms.

Therefore, Gram molecular weight of Calcium carbonate = Gram atomic weight of Calcium +Gram atomic weight of Carbon+ 3(Gram atomic weight of Oxygen)

Gram molecular weight of Calcium carbonate = 40 g mol^-1+ 12g mol^-1+ 3(16g mol^-1)

= 100 g mol^-1

Step-2: Calculate the number of moles

$Numberofmoles=\frac{Givenweightofthesubs\tan ce}{Grammolecularweightofthesubs\tan ce}$

$Numberofmoles=\frac{5}{100}=0.05$ mol

Therefore, the number of moles in 5 g of CaCO₃ is 0.05 mol.