Question

a.     Distinguish between the terms isotope and allotrope. Give appropriate examples.

b. Hydrogen has two naturally occurring isotopes: normal hydrogen (H), with atomic mass of 1, and deuterium (D), with atomic mass of 2. A mixture containing equal number of moles of H₂ and D₂ is allowed to effuse down a capillary. What per cent of the molecules effusing first would be D₂?

c. The two gaseous forms of elemental oxygen are O₂ and O₃. A mixture containing equal quantities of O₂ and O₃ is allowed to effuse down a capillary. What per cent of the molecules effusing first would be O₃?

Answer 1

a)

isotope --> an element which has different count of neutrons, yet, same amount of protons. Examples, C-12 and C-14 isotops

allotrope --> most stable/preferable configuration or presentation of an element

For instance, Carbon as --> diamond, graphite

b)

First, apply graham law:

let 1 = norma, 2 = D

rate 1 / rate 2= sqrt(MW2/MW1)

rate 1 = rate 2*  sqrt(2/1)

rate 1 = 1.4142 * rate 2

Then, if total rate = rate 1 + rate 2 =  1.4142 * rate 2 + rate 2

fraction = rate 2 / (1.4142 * rate 2 + rate 2)

frac. = 1/(1.4142 +1)

frac. 0.4142= will be D2 and 1-0.4142 = 0.5858 will be normal

D2 = 41.4%

c)

Similarly:

rate O2 / rate O3 = sqrt(MW O3/MW O2)

rate O2 / rate O3 = sqrt( 48/32)

rate O2 / rate O3 = 1.224

rate O2 = 1.224*rate O3

assume total rate:

rate total = rate O2 + rate O3 = 1.224*rate O3 + rate O3

frac. rate O3 / 1.224*rate O3 + rate O3)

1/(1.224+1) = 0.4496 is O3 = 44%