Alkanes
4 marks · NormalThe alkane with six carbon atoms is called hexane.
Write the molecular formula for hexane.
Draw the displayed (structural) formula of hexane.
Give the name of the alkane with three carbon atoms in a straight chain.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) C6H14
(b) CH3-CH2-CH2-CH2-CH2-CH3 · must show Six carbon atoms in a straight chain, each with correct hydrogens
(c) Propane
Must show: Correct number of carbon and hydrogen atoms in formulas and structures
Common mistakes: Forgetting two hydrogens at the end of chains
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Gives the correct molecular formula for hexane: C6H14.
B2 (b) · 1 mark · Attempts a straight-chain structure for 6-carbon alkane.
B3 (b) · 1 mark · Each carbon is bonded to the correct number of hydrogens in the full displayed formula.
B4 (c) · 1 mark · Gives the correct name: propane.
Worked solution
(a) The molecular formula for hexane is C6H14.
(b) The displayed formula of hexane is:
or drawn in full with all bonds shown.
(c) The name of the three-carbon straight chain alkane is propane.