Question

Calculate the no of molecules in 21.2 g of sodium carbonate

Answer 1

mass of sodium carbonate = 106

Hence, moles = 21.2/106 = 0.2 mole

1 mole ➡️ 6.022×10²³ molecules

So, 0.2 mole ➡️ x

By cross-multiplication,

x = 1.2044×10²³ molecules.

Answer 2

molecular mass of na2co3 is 106

hence no. of moles = 21.2/106= 0.2

no. of molecules = 0.2*6.02*10^23 =12.04*10^22