Question

21) How many Nitrogen atoms are there in 12.4 g of Ca(NO3)2?

Answer 1

No of moles of Ca(NO3)2 = Given Wt / Molecular Wt

= 12.4 g / 164 g/mol

= 0.076 mol

Now,

1 mole Ca(NO3)2 have 2 moles of N.

0.076 mole Ca(NO3)2 : 0.152 mol N

Now,

1 mole = 6.022*1023 atoms

Thus,

0.152 mole N = 9.15*1022 atoms

Thus,

12.4 g Ca(NO3)2 have 9.15*1022 atoms of N