Scheme of Analysis #5

Flame test:
- Clean wire loop
- Dip the tip of the wire loop into solution (If solid, dip the tip in DIW then dip the soaked wire loop in to the solid)
- Proceed to placing the tip into fire (from Bunsen burner)
- Observe
- Na+ = bright orange
-Cu2+ = green
- K+ = Violet (Can be masked by Na+)
- Ca+ = Brick Red
- H4N+ = no color
Cobaltnitrite test for K+:
-Heat NH4+ off
-In a small test tube/vial, or spot plate and place 10-15 drops of solution to test
-Then add a drop of 6M HAc and 2-3 drops of sodium cobaltnitrite reagent
-Observe
- ppt forms = K+ and/or H4N+
- no ppt = No K+ or H4N+
Blue Litmus test for H4N+:
-Mix the sample in DIW
-Add 6M NaOH
-Suspend damp red litmus
-Observe
- red litmus turns blue = H4N+ pH test:
-Test sample solution with Indicators
-2 HSO4 ; 3-5 Al(OH2)63+;4 Cu2+; 5-6 (NH4 , Mg(OH2)62+,Zn(OH2)62+ ; 7 neutral ions (Ag+, Na+, K+, Ca2+,) ; 13 OH- ;
Test for Cl-:
-add 1M HONO2 till solution is acidic test
-Add 1 drop of 0.02M AgNO3 to small amount of sample solution
-Stir and observe
- if solution turns cloudy = Cl-
Test for SO42-: ( same as Cl- test but with 0.025M Ba(NO3)2 instead of 0.02M AgNO3)
-white ppt = SO42-
Test for HOSO3-:
-pH test then “Test for SO42-“
- If “Test for SO42” is positive with pH ~2.0 = HOSO3-
- If “Test for SO42” is positive with pH ~7.0 = SO4-
Test for NO3-:
-Place a single crystal of Fe(OH2)6(H4N)2(SO4)2 in a spot plate
-Then add small amount of sample solution
-Then add two drops of 18M H2SO4 (running on the side)
- if brown solution forms = NO3-

Na+, K+, H4N+, Ca2+, Mg(OH2)6 2+, Al(OH2)6 3+
Na+, K+, H4N+, Ca2+, Mg(OH2)6 2+, Al(OH2)6 3+

Xs 3-6 MH3N
Xs 3-6 MH3N

negative negative positive positive negative negative positive positive Na+ present
Na+ present
K+ present
K+ present
Cobaltnitrite test

Cobaltnitrite test

Na+, K+
Na+, K+
Ca2+ present
Ca2+ present
Ppt formed
Ppt formed
No ppt formed
No ppt formed
K+? Na+?
K+? Na+?
Ca2+?