Question

Argon, oxygen and nitrogen are obtained from air by fractional distillation. Liquid air, at -250oC, is warmed up, and the gases are collected one by one .
(a) Is liquid air a mixture or pure substances?
(b) Explain why fractional distillation is used rather than simple distillation?
(c) During the distillation, nitrogen gas is obtained first, then argon followed by oxygen. What can you say about the boiling point of these gases?
Please answer fast i need it urgent.....Please answer all the 3 parts given above......Thank you

Answer 1

(a) Air is a mixture and not a pure substance as it contains many gases which can be separated by physical methods and it also shows the properties of its constituents.

(b) Simple distillation is used to separate components when the difference in temperature of their (constituents') boiling points is more than 25℃. Fractional distillation is used when the difference in temperature of their (constituents') is less than 25℃. As air contains various gases and the difference in temperature of their boiling points is less than 25℃, fractional distillation is used here.

(c) During the distillation, nitrogen gas is obtained first, then argon followed by oxygen, this is because in distillation process the gas which has lowest boiling temperature evaporates, condenses and gets collected in the beaker first. Nitrogen has the lower boiling point as compared to argon and oxygen that is why it is obtained first, then followed by the other two.