Organic Analysis Flashcards
What is the test for alkenes? What is a positive result?
Bromine water - Orange bromine water was decolorised
What is the test of halogenoalkanes? What is a positive result?
Add NaOH and warm
Acidify with HNO3, and add AgNO3
- Precipitate of AgX will form
What is the test for alcohols? What is a positive result?
Add acidified potassium dichromate - orange to green
What is the test for alcohols? What is a positive result?
Add acidified potassium dichromate and heat - orange to green
Test for aldehydes (2 Ways)
Warm with tollens reagent - Silver mirror (Ag ppt forms)
Warm with Fehlings solution - Brick red precipitate from blue
How do you test for carboxylic acid? What is a positive result?
Add sodium hydrogen carbonate - effervescence of CO2
What is Mass Spectrometry? How does it work?
Finds the relative molecular masses or organic compounds
Compound is dissolved in solution, ionised by a high voltage supply (to mostly 1+ ions), accelerated by a negatively charged plate, becomes a beam of ionised molecules, reach detector and cause a current to flow. Time of flight used to work out m/z value and plot graph.
What is on the x axis of a mass spectrum
Shows M/Z value (mass divided by ionic charge)
Why are there multiple peaks on a mass spectrometer
The compound may fragment into smaller molecules so these peaks are also shown. Also shows other isotopes of atoms.
What is high resolution mass spectrometry
Mass Spectrometers that give mr to 3d.p or 4d.p
Why do chemical bonds absorb infrared radiation
they are constantly vibrating so they absorb infrared at the same frequency of their vibration
How do strong bonds effect vibration
They vibrate faster
How does infrared spectroscopy work
Every bond has a unique vibration frequency in the infrared region of the EM spectrum
Bonds absorb radiation that has the same frequency as their frequency of vibration
Infrared radiation emerged from a sample is missing the frequencies that have been absorbed -> this information can be used to identify the compound’s functional group
What is the fingerprint region
Area of infrared spectrum below 1500cm-1
Many peaks caused by complex vibrations of the whole molecule. Unique to every compound
How is ion abundance determined in a mass spectrometer
At the detection plate, ions gain an electron
Abundance depends on current size
