3.1.4 Qualitative analysis Flashcards
1
Q
What are the negative ions we test for
A
Carbonate
Sulfate
Halide
2
Q
Carbonate ion
A
CO3 2-
3
Q
Sulfate ion
A
SO4 2-
4
Q
Halide ion
A
Cl-
Br-
I-
5
Q
What is the positive ion we test for
A
Ammonium
6
Q
Ammonium ion
A
NH4 +
7
Q
Testing for carbonates
A
Add dilute acid
Bubble gas through limewater, will turn cloudy if present
Will fizz
2HCl + Na2CO3 -> H2O + CO2
8
Q
Testing for sulfates
A
Add acidified BaCl2
White ppt will form
Ba2+ (aq) + SO4 2- -> BaSO4 (s)
9
Q
Testing for halides
A
Nitric acid then silver nitrate
Chlorine= white ppt dissolves in dilute and conc ammonia Bromine= cream ppt dissolves partially in dilute and fully in conc ammonia Iodine= yellow ppt doesn’t dissolve in ammonia
Ag+ (aq) + Cl- (aq) -> AgCl (s)
AgCl (s) + 2NH3 (aq) -> [Ag(NH3)2]+(aq) + Cl- (aq)
10
Q
Test for ammonium
A
React ammonium ion with warm NaOH (aq) to form NH3 gas
Turns damp litmus blue
11
Q
Order for testing
A
Carbonates
Sulfates
Halides
