How can you test for alcohol using phosphorus(V) chloride? ( 2 marks)
Reacting your alcohol with PCl5 will result in the formation of steamy fumes of HCl forming, which turn moist blue litmus paper red ( because the HCl dissovles to form a strong acid)
HCl also dissolves in water to form chloride ions which presence can be tested using silver nitrate
What the balanced equation for phosphorus(III) halide (iodide) and alcohol and what condition are need for it to be made
PI3 + 3CH3CH2OH → 3CH3CH2I + H3PO3 In situ by refluxing the 'red phosphorus' in either bromine or iodine
What happens when primary alcohols when they reacts with a limited amount of potassium dichromate?
The alcohol turns into an aldehyde and water
What happens when primary alcohols when they reacts with a excess amount of potassium dichromate?
the alcohol turns into a aldehyde then a carboxylic acid.
What the name of the apparatus used to prepare carboxylic acid from primary alcohols and what is it made up from? ( 4 marks)
circle instead of pear
round bottom flask
How do you conduct an experiment to get carboxylic acid from primary alcohol, what the advantage of using this technique and what observation is seen ? (4 marks)
Using a reflux apparatus
Excess Potassium dichromate (VI) and dilute sulfuric acid is added with alcohol along with anti bumping granules to make the boiling smoother and is heated.
This allows violtile solvents to boil without being lost as any vapourised compounds are condensed and put back into the mixture
Orange dichromate solution changes to green colour
What is the suffix used to describe a aldehyde
What is the word equation required to form a carboxylic acid and what is the suffix for carboxylic acids?
Aldehyde + water → Carboxylic acid
What happen when a secondary alcohol and potassium dichromate( VI) react and what the observation seen?
A ketone is made with water
the orange dichromate ion (Cr2O7 2-) reduces to the green Cr 3+ ion
What happen when a tertiary alcohol reacts with potassium dichromate (VI) and why?
This is because there is no hydrogen atom bonded to the carbon with the OH group
What the name of the technique that can be used to prepare a ketone from a secondary alcohol and how does it work? ( 2 marks)
Secondary alcohol is heated with acidified potassium dichromate (VI) at a temperture above the boiling temperture of the ketone but below the boiling temperture of the secondary alcohol ensuring only the ketone reaches the receiving flask
What the name of the technique that can be used to prepare a aldehyde from a from a primary alcohol and how does it work? (3 marks)
Using a limited amount of potassium dichromate (VI) solution and dilute
sulphuric acid, you gently heat the flask until an apple smell is produced indicating an aldehyde has formed.
How do you distinguish between a aldehyde and ketone alcohol and what is observed
React both with Fehlings/ Benedict solution.
Aldehydes :Blue Cu2+ ions in solution change to a brick red precipitate of Cu2O.