Chemical Tests Flashcards
How do you test for halides in a solution
Add silver nitrate + nitric acid
Why add nitric acid when testing for halides within a solution
Remove any carbonates which could react with the halide solutions
Sodium nitrate + nitric acid -> halide precipitates
Cl- -> white
Br- -> cream
I- -> yellow
Halide in solution precipitates + dilute NH3
AgCl —> soluble (dissolves)
AgBr + AgI —> insoluble
Halide in solution precipitates + conc NH3
AgBr —> soluble (dissolves)
AgI —> insoluble
How to test for sulphates
Aqueous barium chloride + dilute HCl
Why add dilute HCl in test for sulfates
So only the sulfate anion will form as the precipitate
Test for sulphates precipitates
SO4^2- —> white
SO3^2- —> white
CO3^2- —> White
Test for sulfates precipitates + HCl
BaSO4 —> insoluble
BaSO3 —> dissolves
BaCO3 —> dissolves
How to test for solid halide
Add a few drops of conc HCl to the halide
Test for solid halide: chloride (observation + inference)
- steamy fumes
- HCl (g)
Test for solid halide: Bromide (observation + inference)
- Steamy fumes - HBr
- brown vapour - Br2
- SO2 (colourless)
Test for solid halide: iodide (observation + inference)
- steamy fumes - HI
- purple vapour - I2
- black solid - S
- yellow solid
- H2S (colourless)
Halide displacement observations - Cl- (+)
Cl2 - no reaction, pale green solution
Br2- no reaction, pale red-brown solution
I2 - no reaction, brown solution
Halide displacement observations - Br- (+)
Cl2- red-brown solution, yellow-orange organic layer
Br2- no reaction, pale red-brown solution
I2- no reaction, brown solution