Introduction to organic chemistry

Question 1

what is a petroleum fraction?

Answer 1

mixture of hydrocarbons with a similar chain length and boiling point range

Question 2

How are hydrocarbons separated in fractional column

Answer 2

• Oil is pre-heated
• then passed into column
• The fractions condense at different heights
• The temperature of column decreases upwards
• The separation depends on boiling point
• Boiling point depends on size of molecules
• The larger the molecule the larger the Van Der Waal’s forces
• Similar molecules (size, bp, mass) condense together
• Small molecules condense at the top at lower temperatures
• and big molecules condense at the bottom at higher temperatures.