Alkanes
4 marks · NormalDraw and name the displayed formulae for the following straight-chain alkanes.
An alkane with four carbon atoms.
An alkane with five carbon atoms.
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) Butane; displayed formula: CH3–CH2–CH2–CH3 · must show 4 carbon atoms in a straight line, all single bonds, correct hydrogens
(b) Pentane; displayed formula: CH3–CH2–CH2–CH2–CH3 · must show 5 carbon atoms in a straight line, all single bonds, correct hydrogens
Must show: Correct displayed structure for each, Correct name for each
Common mistakes: Missing hydrogens; Wrong alkane name
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Draws correct displayed formula for butane.
B2 (a) · 1 mark · Names: butane.
B3 (b) · 1 mark · Draws correct displayed formula for pentane.
B4 (b) · 1 mark · Names: pentane.
Worked solution
(a) The four-carbon alkane is butane.
(b) The five-carbon alkane is pentane.