Question

One way of separating oxygen isotopes is by gaseous diffusion of carbon monoxide. The gaseous diffusion process behavles like an iffusion process. Calculate the relative rates of effusion of ¹²C¹⁶O, ¹²C¹⁷O, and ¹²C¹⁸O.

List some advantages and disadvantages of separating oxygen isotopes by gaseous diffusion of carbon dioxide instead of carbon monoxide.

Answer 1

for O16 mass number = no of protons+no of neutrons=8+8=16

for O17 mass number = no of protons+no of neutrons=8+9=17

for O18 mass number = no of protons+no of neutrons=8+10=18

atomic mass is almost same to mass number.

Molecular mass of CO(16)(8 neutrons+8 protons) =12+16=28g

Molecular mass of CO(17) =12+17=29g

Molecular mass of CO(1) =12+18=30g

According to Graham's Law effusion rate of a gas is inversely proportional to the square root of the mass of its particles.

effusion rate for CO(16) is

effusion rate for CO(16) is

effusion rate for CO(16) is

So relative rate of effusion are:

:   :

29.4958:28.9827:28.4956

1.035 : 1.017 : 1

Hence order of effusion is

CO(16)>CO(17)>CO(18)

If we take CO₂ instead of CO then diffusion rate are in ratio

46.98936:45.9565:44.98888

Advantage of CO2 over CO

effusion ratio for CO2 are

1.0445:1.0215:1

which has more difference as compared to effusion ratio of CO

which is 1.035 : 1.017 : 1

Hence for CO2 gas oxygen can be easily separated.

Moreover,CO bond is much stronger in Carbon Monoxide than CO bond in CO2 so it is diffcult to separate Oxygen from CO

CO is toxic

Disadvantage of CO2 :CO diffuses faster than CO2 because of less molecular weight so in case of CO2 time required for separation of isotope of oxygen is more than that in case of CO.