Chemical Analysis Flashcards
What is formulation
formulation is a mixture that has been designed for a specific purpose to deliver a commercial product
Mobile phase
mobile phase is the solvent in which the sample molecules can move, which in paper chromatography is liquid e.g. water or ethanol
Stationary phase
stationary phase in paper chromatography is the actual chromatography paper itself
Rf calculated by :
Distance moved by substance
Divided by
Distance moved by the solvent
Squeaky pop test
The test for hydrogen consists of holding a burning splint held at the open end of a test tube of gas
- burns with a loud “squeaky pop” which is the result of the rapid
combustion of hydrogen with ovaen to produce water
• Be sure not to insert the splint right into the tube, just at the mouth, as the gas needs air to burn
Glowing splint test
The test for oxygen consists of placing a glowing splint inside a test tube of gas
• If the gas is oxygen the splint will relight
Limewater Test
The test for carbon dioxide involves bubbling the gas through an aqueous solution of calcium hydroxide (limewater)
• Itthe gas is carbon dioxide, the limewater turns milky or cloudy
Litmus paper test
If chlorine gas is present, damp blue litmus paper will be bleached white
• It may turn red briefly before bleaching, as acids are produced when chlorine comes into contact with water
Flame test
Metal ions produce colour if heated strongly in flame
Li = red
Na = yeallow
K = lilac
Ca = orange-red
Cu = blue-green
Metal hydroxides
Metal cations in aqueous solution can be identified by the colour of the precipitate they form on addition of sodium hydroxide
Al = colourless -white precipitate dissolves in excess NaOH
Mg = white precipitate - insoluble so remains
Ca =white precipitat
Cu = light blue precipitate
Iron 11 = green precipitate
Iron 111 = red brown precipitate
Test for carbonates
Limewater turns milky in the presence of CO2 caused by formation of insoluble calcium
carbonate
Silver nitrate test
Silver chloride is white. silver bromide is cream and silver iodide is vellow
Test for sulfates
Acidify the sample with dilute hydrochloric acid and then add a few drops of aqueous
Coarina chorde
• t a sultateis present then a white precipitate ot barium sultate is formed
Advantages of instrumental methods
Methods of analysis include X-ray, Infra-Red and Mass Spectroscopy, Gas Chromatography and Flame Photometry
advantage of using these instruments over more traditional methods include:
They provide greater accuracy
• They are faster and easier to use
They are automated and can perform multiple simultaneous sampling and testing
• Modern instruments are very sensitive and can work with verv small sample sizes
