Question

How many moles and how many atoms are present in 11.5 g of sodium? Use N_A = 6×10²³

Answer 1

Molar mass of Na=23g/mol

no. of moles = weight/molar mass

n = 11.5/23

no. of moles = 0.5

no. of moles = no. of atoms/avogadro’s number

0.5 = no. of atoms/6.022*10^23

0.5*6.022*10^23 atoms = no. of atoms

3.011*10^23 atoms.

So there are 3.011*10^23 atoms present in 11.5g of sodium sample.