Question

How many nitrogen atoms are present in a 1.73 g sample of molecular nitrogen? You must report the answer in scientific notation displaying only 3 significant figures Formatting convention that must be used to input a number in written in scientific notation: 1.22 x 104 1.22E2

Answer 1

Molar mass of N2 = 28.02 g/mol

mass(N2)= 1.73 g

use:

number of mol of N2,

n = mass of N2/molar mass of N2

=(1.73 g)/(28.02 g/mol)

= 6.174*10^-2 mol

use:

number of molecules = number of mol * Avogadro’s number

number of molecules = 6.174*10^-2 * 6.022*10^23 molecules

number of molecules = 3.718*10^22 molecules

Count of each element in compound is:

{N=2}

Total number of atoms in 1 molecule = 2

use:

number of atoms = number of molecules * Total number of atoms in 1 molecule

number of atoms = 3.718*10^22 * 2

number of atoms = 7.436*10^22

Answer: 7.44E22