Question

23) Calculate the number of moles, molecules and total number of atoms
present in 1.1x10-4 kg of Co2
​

Answer 1

Explanation:

Mass of CO

2

=1.1×10

−4

Kg

Molar mass of CO

2

=12+32

⇒44gmol

−1

⇒44×10

−3

Kgmol

−1

(i) Number of moles (n)=

MolarmassofCO

2

MassofCO

2

=

44×10

−3

Kgmol

−1

1.1×10

−4

Kg

⇒n=2.5×10

−3

mol

(ii) Number of molecules of CO

2

=n× Avogadro's number

=2.5×10

−3

×6.022×10

23

=1.5×10

21

molecules

(iii) Number of atoms present= 1.5×10

21

×3

=4.5×10

21

atoms

CO

2

is triatomic, hence multiplied by 3.