Chapter 29 - Chromatography and Spectroscopy Flashcards
Test for Alkene?
Add bromine water. It should decolourise. Orange to colourless.
Test for haloalkane?
Add silver nitrate and ethanol and warm to 50 degrees in a water bath. Chlorine forms white precipitate. Bromine forms cream precipitate and iodine forms yellow precipitate.
Test for carbonyl group (aldehyde and ketone)?
Add Brady’s reagent. Forms an orange precipitate.
Test for aldehyde?
Heat with Tollen’s reagent. Forms silver mirror
Test for primary/secondary alcohol?
Reflux with acidified potassium dichromate. Colour change from orange to green
Test for carboxylic acid?
Add sodium carbonate (Na2CO3). Effervescence if acid is present.
Test for phenol?
They are not as acidic as carboxylic acids so do not react with sodium carbonate but can still show acidity with pH indicator paper. Add bromine to solution of phenol. Bromine decolourises and white precipitate forms.
What is the stationary phase for TLC?
Solid adsorbent substance - usually silica
What is the mobile phase for TLC?
Solvent for the solute.
What is adsorption?
The adhesion of modules to a solid surface. Seperation of substances is achieved by their relative adsorptions to the stationary phase.
What is the stationary phase in gas chromatography?
A high boiling liquid adsorbed onto an inert solid support
What is the mobile phase in gas chromatography?
An inert gas like neon or helium
How are compounds seperated in gas chromatography?
It depends on their relative solubility in the liquid stationary phase
What is retention time?
The time taken for each component to travel through the column.
What is a TMS peak?
A standard reference chemical against which all the chemical shifts are measured. It’s formula is (CH3)4Si.
What are deuterated solvents?
A solvent used in NMR spectroscopy. An example is CDCl3.
What is the purpose of D2O?
Involved in proton exchange. If passed through proton nmr spectrum, OH and NH peaks disappear.
