Calculate the following quantities in 5.6 g of nitrogen (Atomic mass of N =14u) : (a) Number of moles of N2. (b) Number of molecules of N2. (c) Number of atoms of nitrogen

CBSE Class 9 CBSE Class 9 Science
1

Mass of nitrogen = 5.6 g
Atomic mass of N = 14 u
Molar atomic mass of N = 14 g / mol ,
Molar mass of N2 = 2 x 14 g / mol = 28 g mol-1

(a) No. of moles of N2 in 5.6 g of nitrogen
= 5.6 g/28 g mol-1
= 0.2 mol

(b) No. of molecules of N2 is 5.6 g of nitrogen
= 6.023 x 10^23 x No. of moles of N2
= 6.023 x 10^23 x 0.2
= 1.2 x 10^23

© As one molecule of N2 contains two N atoms.
No. of atoms of nitrogen
= 2 x No. of N2 molecules
= 2 x 1.2 x 10^23 = 2.4 x 10^23