Qualitative Analysis
This refers to the process used to determine the elements present in a compound and what form they are in
Ways to test for Hydrogen
Using colorless anhydrous Copper Sulfate (CuSO4)
Using Cobalt (II) Chloride (CoCl2)
Test for Hydrogen using Copper Sulfate (CuSO4)
The compound is heated with CuO (Copper (II) Oxide) and the gas produced is passed over anhydrous colorless CuSO4. A blue color change shows confirmation
Test for hydrogen using Cobalt (II) Chloride (CoCl2)
The compound is heated with CuO and the gas is passed over Cobalt (II) Chloride. A color change from blue to pink shows confirmation.
Test for carbon
The compound is heated with CuO and the gas produced is passed over lime water. When the lime water turns milky it shows confirmation
Halogens
Elements that need one electron for their outermost shell to be complete
Examples of Halogens
Fluorine, Chlorine, Bromine, Iodine
Preparing Sodium Extract
Compound is heated with a sodium metal until it is red hot. the compound is dissolved in water and filtered.
Why is the compound heated with Sodium?
To make the compound soluble in water.
Sodium Fusion/ Lassaigne Test
This is a test used for the qualitative determination of halogens (except fluorine), Sulphur and Nitrogen
What compounds can interrupt the test for halogens?
Sulfate (SO42- ) and Cyanide (C-)
How eliminate Sulfate (SO42- ) and Cyanide (CN-)
Add Nitric acid (HNO3 ) to the sodium extract and boil it
Confirmation of Chorine
After addition of AgNO3 to the sodium extract a white precipitate that is soluble in excess NH3 (Ammonia) is formed
Confirmation of iodine
After addition of AgNO3 to the sodium extract a yellow precipitate that is insoluble in excess NH3 (Ammonia) is formed
Confirmation of bromine
After addition of AgNO3 to the sodium extract a pale yellow precipitate that is insoluble in excessNH3 (Ammonia) is formed
Ways to Test for Sulphur
Using Lead acetate
using Sodium Nitroprusside
Test for Sulphur using Lead Acetate
10% of NaOH and this compound is added to the sodium extract. A black precipitate (PbS) is confirmation
Test for Sulphur using Sodium Nitroprusside
This compound is added to the sodium extract. A violet coloration shows confirmation
Test for Nitrogen
Iron (II) hydroxide (Fe(OH)2 ) is added to the sodium extract and on further addition of iron(III) chloride (4FeCl3 ). A prussian blue precipitate forming is confirmation
Test for Oxygen
No direct test for oxygen. Scientists add up other elements and any missing amount is oxygen.
Quantitative Analysis
The methods used to determine the amount of an element in an organic compound
Empirical Formula
This is the formula with the smallest whole number ratio of the elements in a compound
Molecular Formula
This formula shows the actual whole number ratio of elements in a compound
Formula for Molecular formula
Empirical formula*n
Spectrometry
The field of scientific study that measures and interprets electromagnetic spectra
Spectroscopic Methods
Infrared
Ultra Violet
Nuclear Magnetic Resonance
Mass Spectrometry
Infrared Spectroscopy
The spectrometry method used to determine the presence of functional groups
Ultra-violet
This spectrometry method is used to determine the presence or absence of conjugated pi-bonds
Nuclear Magnetic Resonance
This spectrometry is used to determine the structure of compounds at the atomic level
Mass Spectrometry
This is the spectrometry method used to measure the mass to charge ratio of ions. it is also used to determine the molecular mass and formula.