7.3 Products of Reactions Involving Hydrocarbons

Question 1

reactivity of alkane vs alkene and why

Answer 1

alkene more reactive bc high electron density of double bond (unsaturated molecule)

Question 2

how to distinguish between alkane and corresponding alkene

Answer 2

reaction of bromine water

Question 3

bromine water equation

Answer 3

Br2 + H2O ⇌ H+ + Br- + HOBr

forms hypobromous acid

Question 4

colour of bromine water

Answer 4

deep brown or yellow-orange

Question 5

saturated compound (single bond) + HOBr colour

Answer 5

brown colour remains

decolourises in UV light

Question 6

unsaturated compound (double bond) + HOBr

Answer 6

brown –> colourless

Question 7

what happens to HOBr and halogen layer in saturated compound?

Answer 7

halogens are more soluble in the hydrocarbon and move to this top layer when shaken with a hydrocarbon solvent

Question 8

addition reaction of HOBr with C6H10 (cyclohexene)

Answer 8

HOBr + C6H10 –> C5H9BrCHOH

Question 9

what happens in addition reactions

Answer 9

double bond opens up

Question 10

what are substitution reactions

Answer 10

atom replaces another atom

Question 11

substitution reaction with HOBr with C6H12 (cyclohexane)

Answer 11

HOBr + C6H12 + UV light –> C6H11Br + H2O

Question 12

what is hydrogenation

Answer 12

addition reaction where H molecules add onto unsaturated molecules

Question 13

what is hydration/hydrolysis

Answer 13

water added to unsaturated molecules

Question 14

Markovnikov’s rule

Answer 14

(in hydrolysis) the H atom bonds to the Carbon with the most existing H bonds

Question 15

complete combustion with hydrocarbons equation

Answer 15

CnH(2n+2) + (3n+1)/2 O2 –> nCO2 + (n+1)H2O + heat

n = no. of C atoms