Organic Analysis Flashcards
(14 cards)
What do you use to test for alcohols?
Acidified Potassium Dichromate Solution
What is seen when potassium dichromate solution is reacted with a primary or secondary alcohol?
Solution turns from orange to green
What is seen when potassium dichromate solution is reacted with a tertiary alcohol?
No visible change as tertiary alcohols aren’t oxidised.
What can be used to distinguish between aldehydes and ketones?
Tollens’ Reagent
Fehling’s Solution
Describe the test with Tollens’ Reagent.
You add Tollens’ Reagent to the solution being tested. Warm it gently. If an aldehyde is present, a silver mirror will form. If not, the solution will remain colourless.
Describe the test with Fehling’s Solution.
Add Fehling’s Solution to the solution being tested and heat it. If an aldehyde is present, a brick red precipitate will form. If not the solution remains blue.
Describe the test for an alkene.
Add bromine water to the solution. It changes from orange/brown to colourless if a carbon-carbon double bond is present. If not, no change is observed.
Describe the test for a carboxylic acid.
React with sodium carbonate as acids producing CO2. This gas can be collected and tested using limewater. Solution will turn cloudy if the gas is CO2.
What is mass spectrometry used for?
To identify compounds and determine their molecular formula.
What is high resolution mass spectrometry?
A more sensitive form of mass spectrometry which allows the Mr of a substance to be determined to several decimal places.
What is Infrared Spectroscopy?
An analytical technique used to determine functional groups present in organic compounds by using infrared radiation.
How does infrared spectroscopy work?
The IR radiation is passed through a sample where the different types of bonds absorb the radiation in different amounts.
What is the fingerprint region?
The side of the graph lower than 1500. This contains tiny differences from species to species which act as a molecules fingerprint allowing it to be identified.
Describe how IR absorption occurs in the atmosphere.
It causes heat to be trapped within the Earth’s atmosphere. However when chemicals such as CFCs are released into the atmosphere from human activity, the heating effect is enhanced leading to global warming.
