Alkanes

Question 1

straight-chain alkanes

Answer 1

eg butane CnH2n+2

Question 2

branch chain alkanes

Answer 2

eg methyl butane CnH2n+2

Question 3

cycloalkanes

Answer 3

eg cyclohexane CnH2n

Question 4

naming alkanes

Answer 4

C atoms are numbered to give the smallest number to the branch chains and in alphabetical order.

Question 5

melting point and boiling point of straight-chain alkanes

Answer 5

increase as the length of the carbon chain increases because the longer (larger) the molecule, the stronger the forces of attraction are between those molecules.

Question 6

solubility of alkanes in water and other polar solvents

Answer 6

insoluble because alkane molecules are all non-polar (float on water because they have a lower density)

Question 7

solubility of alkanes in other alkanes (or other hydrocarbons)

Answer 7

soluble because these molecules are also non-polar and will dissolve non-polar molecules.

Question 8

substitution reaction

Answer 8

one atom (or group of atoms) is replaced by another atom (or group of atoms)

Question 9

substitution equation

Answer 9

alkane + halogen arrow (UV light) haloalkane + hydrogen halide
C2H6 + Br2 arrow (UV light) bromoethane + HBr (hydrogen bromide)

Question 10

substitution reaction example

Answer 10

ethane + bromine arrow (UV light) bromoethane + hydrogen bromide