Question

Fill in the blanks with appropriate words selected from those given below.

heights, condense, lower, bitumen, hydrocarbons, high, fractional distillation, cool, fractionating column, diesel oil, petrol, refinery, higher up, lower down

(a) Crude oil is made up of many different ___________. In an oil ___________, the hydrocarbons are separated into different products by a process called _____________ ___________. The crude oil is heated to a high temperature and passed into the____________ __________. As the vapours rise towards the top the different hydrocarbons ___________ at different ___________ and are withdrawn separately.
(b) Substances with _____________ boiling points condense first, in the column. Substances with ___________ boiling points condense ______________. Light products like ___________ are withdrawn from near the top of the column. Heavier products like ___________ and fuel oil are taken out lower down. The heaviest hydrocarbons, such as __________ are left at the bottom.

Answer 1

(a) Crude oil is made up of many different hydrocarbons. In an oil refinery, the hydrocarbons are separated into different products by a process called fractional distillation. The crude oil is heated to a high temperature and passed into the fractionating column. As the vapours rise towards the top, the different hydrocarbons condense at different heights and are withdrawn separately.
(b) Substances with lower boiling points condense first in the column. Substances with high boiling points condense lower down. Light products like petrol are withdrawn from near the top of the column. Heavier products like diesel oil and fuel oil are taken out lower down. The heaviest hydrocarbons, such as bitumen, are left at the bottom.