Organic Analysis Flashcards
Describe a test for alkenes.
Add bromine water, decolourises if bromine is present.
Describe a test for halogenoalkanes.
Warm the sample with aqueous NaOH, hydrolysing it to produce a halide ion. Add HNO3 (removes impurities) and finally add Tollen’s reagent. White precipitate shows a chloroalkane, cream preticipate shows a bromoalkane, yellow precipitate shows a idoalkane.
Describe a test for alcohols.
Add potassium dichromate. Colour change fro orange to green if a primary or secondary alcohol is present.
Describe a test for an aldehyde.
Add Tollen’s reagent. Silver mirror will form if an aldehyde is present.
Describe a test for a carboxylic acid.
Add aqueous solution of sodium hydrogencarbonate. Effervescence is carboxylic acid is present.
What does the mass spectrometer show and what is the information used to find?
Measures the relative abundance which can then be used to calculate the relative atomic mass.
What does the vertical axis of the mass spectrum show
The relative abundance
What does the horizontal axis of the mass spectrum show?
The mass/charge ratio of the ions reaching the detector.
What is high resolution mass spectrometry used for?
Determining the precise mass of a compound so the identity of the substance can be deduced.
How does infrared spectrometry allow identification of functional groups.
By seeing which wavelengths have been absorbed
What is the fingerprint region?
The area of an infrared spectrum between 400cm^-1 and 1500cm^-1 which is unique for each compound.
How does infrared specrometry work?
All bonds have their own unique frequency of vibration. A beam of infrared radiation is passed through a sample, the radiation emerges and is missing the frequencies that correspond to the types of bond found in the sample and plots a graph of transmittance against frequency of radiation.
