23. A certain sample of nitrogen gas consists of 9.26 1022 nitrogen atoms. (a) How many moles of N atoms are present in this sample ?
(b) If the gas is entirely in molecular form, how many molecules are present in this
sample?
(c) What is the mass of the sample in gramme?

a) 0.154 moles of N2

b) 9.27 × 10^22 molecules

c) 4.312 g

Explanation:

a)

1 mole of N2 contains 6.02 × 10^23 atoms

x moles of N2 contains 9.26 × 10^22 atoms

x= 9.26 ×10^22/6.02 × 10^23

x= 1.54 ×10^-1

x= 0.154 moles of N2

b)

1 mole of N2 contains 6.02 × 10^23 molecules

0.154 moles of N2 contains 0.154 moles × 6.02 × 10^23 = 9.27 × 10^22 molecules

c)

Molar mass of the nitrogen gas= 28 gmol^-1

Number of moles of nitrogen gas = 0.154 moles

Number of moles = mass/molar mass

0.154 moles= mass/28 gmol^-1

Mass= 0.154 moles × 28gmol^-1

Mass= 4.312 g

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