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8 Read the information from the table and answer the questions given below.
Name of the gas Hydrogen (H2) Oxygen (O2) Methane (CH4) Carbon dioxide (CO2)
Molecular mass 2 32 16 44
a) Which gas has least rate of diffusion?
b) In Oxygen and Carbon dioxide which gas spread easily?
c) Which gas diffuses rapidly. Why?
d) Arrange the gases in increasing order of diffusion rate.
Answers
) Molecular mass of H2= 2 x Atomic mass of H= 2 x 1
= 2 u
ii) Molecular mass of O2= 2 x Atomic mass of O
= 2 x 16
= 32 u
iii) Molecular mass of Cl2= 2 x Atomic mass of Cl
= 2 x 35.5
= 71 u
iv) Molecular mass of CO2= Atomic mass of C + 2 x Atomic mass of O
= 12 + 2 x 16
= 44 u
v) Molecular mass of CH4= Atomic mass of C + 4 x Atomic mass of H
= 12 + 4 x 1
= 16 u
vi) Molecular mass of C2H6= 2 x Atomic mass of C + 6 x Atomic mass of H
= 2 x 12 + 6 x 1
= 30 u
vii) Molecular mass of C2H4= 2 x Atomic mass of C + 4 x Atomic mass of H
= 2 x 12 + 4 x 1
= 28 u
viii) Molecular mass of NH3= Atomic mass of N + 3 x Atomic mass of H
= 14 + 3 x 1
= 17 u
ix) Molecular mass of CH3OH= Atomic mass of N + 3 x Atomic mass of H
= 12+ 4 x 1+16
= 32 u
B.carbondioxide has least rate of diffusion
C.oxygen spreads easily
D. At any given temperature, small, light molecules (such as H 2, hydrogen gas) diffuse faster than larger, more massive molecules (such as N 2, nitrogen gas) because they are traveling faster, on the average (see heat ; kinetic-molecular theory of gases
E.gases in the order of increasing rate of diffusion: SO3, CH4, H2, N2O, Cl2, O3, He.