Topic 6 Flashcards
What type of reaction is where alcohols react with concentrated phosphoric acid to form alkenes?
ELIMINATION
What is meant by stereoisomers?
- compounds with same structural formula
Where the atoms have a different displayed formula
CH3CH2CH2CH2OH reacts with the oxidising agent potassium dichromate(VI) in dilute sulfuric acid.
Two organic products can be formed, depending on the conditions.
Write a balanced equation for the formation of one of these products, giving its name and the condition required to achieve this product in high yield.
Use [O] in the equation to represent each oxygen atom from the oxidising agent.
Equation
Name ……………………………………………………………………………………………………………………………
Condition ………………………………………………………………………………………………………………………
CH3CH2CH2CH2OH + 2[O] -> CH3CH2CH2COOH+ H2O
BUTANOIC ACID
HEAT UNDER REFLUX
One reason why the yield calculated is less than 100%
- side reactions
- incomplete
- transfer losses
Deduce a chemical test for a C=C bond
Bromine water
Orange/ brown goes colourless
Devise a procedure to obtain a pure dry sample of cyclohexane from the distillate
- separate cyclohexane from water using SEPARATING FUNNEL
- remove AQUEOUS layer as it has a higher density
- use a drying agent (metal Sulfates)
- separate cyclohexene from drying agent
- redistil product (by FILTRATION OR DECANTATION)
-collect after boiling at temp between 80-86
Using apparatus for distillation instead of reflux is not an efficient way to produce ethanoic acid from ethanol. Explain why.
Ethanol would be OXIDISED to ethanal
Ethanal has a LOW BP
Give a reason for the addition of ethanol to each test tube (1)
Increases solubility or dissolves the halogenoalkane
Give a reason why the test tubes were left in the water bath for 5 mins before adding the halogenoalkanes (1)
Allow solutions to equillbrate and reach required temperature
Explain why halide ions are present in the mixture containing a halogenoalkane which only has covalent bonds (2)
(Halogenoalkane) hydrolysed by water
C-Hal bond breaks (heterolytically producing ions)
Write the ionic equation with state symbols for the reaction involving silver nitrate in test tube X (1-chlorobutane)
Ag+ (aq) + Cl- (aq) -> AgCl (s)
Which of the following DOES NOT act as a nucleophile
- HBr
- H2O
- NH3
- CN-
HBr
what type of reaction occurs when propene reacts with HCl?
electrophilic addition
Q: NAME the reagents used in reaction 1
chloropropane can react to form organic products as shown in the reaction scheme:
CH3 CH CH2 Reaction 1
CH3 CH2 CH2 C N
Reaction 2
CH3CH2 CH2 Cl Reaction 3
concentrated ammonia solution heated in a sealed tube
CH3 CH2 CH2 NH2
Reagent: NaOH/ KOH
condition: ethanol and heat
ii) Identify a suitable reagent for Reaction 2 and include a reason why this is a particularly useful type of reaction in organic chemistry. (2)
chloropropane can react to form organic products as shown in the reaction scheme:
CH3 CH CH2 Reaction 1
CH3 CH2 CH2 C N Reaction 2
CH3 CH2 CH2 Cl Reaction 3
concentrated ammonia solution heated in a sealed tube=
CH3 CH2 CH2 NH2
KCN/NaCN /potassium cyanide / sodium cyanide (1)
Reason:
increases the number of carbon atoms in the carbon chain/ length of carbon chain
Explain why, in reaction 3, the reagents are HEATED in a sealed container
chloropropane can react to form organic products as shown in the reaction scheme:
CH3 CH CH2 Reaction 1
CH3 CH2 CH2 CN Reaction 2
CH3 CH2 CH2 Cl Reaction 3
concentrated ammonia solution heated in a sealed tube
CH3 CH2 CH2 NH2
heating increases rate (of reaction) (1)
no sealed tube would result in loss of ammonia (gas)/ reactants / gas
Write the structural formula of the product that will be formed if 1-chloropropane is refluxed with aqueous potassium hydroxide solution
CH3 CH2 CH2 OH
explain why isomers of hexane have lower boiling temps and so are found in the petrol fraction (3)
isomers have branched chains
branched chains have lower SA
Intermolecular forces are weaker
explain the 2 major reasons for cracking hydrocarbons (3)
SHORTER chain alkanes AND alkenes formed
alkenes used to make polymers/plastics
shorter chain alkanes are more in demand
describe 2 charactersitics of the homologous series
same general formula
same functional group
what is meant by structural isomer?
same molecular formula
different displayed formula
state the purpose of adding ethanol to test tubes
to dissolve BOTH the laogenoalkane and water
give one reason why the test tubes are placed in the same beaker of hot water
same temperature
give one reason why the test tubes were shaken after the addition of aq silver nitrate
ensure reactants are mixed thoroughly
state how the halogen atom present in each halogenoalkane can be identified from observations in the experiment
CL- white
Br - cream
I - yellow
identify further reagents that can be added to confirm the identity of the halogen atom present in each halogenoalkane (2)
dilute AND conc ammonia solution
silver chloride, silver bromide and silver iodide
