CH.15 Hydrocarbons

Question 1

cracking conditions

Answer 1

high temperature
Al2O3 catalyst, aluminium oxide
no oxygen in cracking

Question 2

what reactions can alkenes be made from

Answer 2

cracking of alkanes
elimination of hydrogen halide ex.HCl from a halogenoalkane by heating with ethanolic sodium hydroxide
dehydration of alcohol by using a heated catalyst ex. Al2O3 or a concentrated acid

Question 3

(Hydrogenation) addition of hydrogen to an alkene conditions and product

Answer 3

heat
alkene passed over a finely divided platinum/ nickel catalyst
product- alkane

Question 4

addition of hydrogen halide conditions and product

Answer 4

bubbled through a concentrated solution of hydrogen halide at room temperature

with longer asymmetric alkenes two products possible (primary or secondary)

Question 5

addition of steam conditions and product

Answer 5

steam and gaseous alkene at high temperature and pressure
concentrated phosphoric acid, H3PO4 catalyst

Question 6

oxidation of alkenes to produce a diol

Answer 6

oxidising agent- cold dilute acidified potassium manganate (VII) KMnO4 (aq)
room temp
Pale purple turns colourless
alkene converted to diol
can be used to test if a compound is unsaturated (like the more commonly used bromine water test)

Question 7

oxidation of alkenes using hot concentrated acidified potassium manganate (VII) solution

Answer 7

pg.315 figure 15.19