CHEMICAL TESTS Flashcards
Sulphate ions (SO4 2-)
1) acidify with HCl
2) add BaCl
Positive - white precipitate (BaSO4)
Test for Carbonate ions (CO3 2-)
Add dilute HCl
Effervescence - gas produced
Turns lime water cloudy
Hydroxide ions (OH-)
1) damp RED litmus paper
Positive turns red to blue
Halide Cl-
1) acidify with HNO3 (not HCl due to Cl- ion present in acid!)
2) add AgNO3 - silver nitrate solution
3) add dilute NH3 then conc. NH3 (to double check)
Positive = white ppt
Also dissolves in the dilute ammonia!
Halide Br-
1) acidify with HNO3 (not HCl due to Cl- ion present in acid!)
2) add AgNO3 - silver nitrate solution
3) add dilute NH3 then conc. NH3 (to double check)
Positive = cream ppt
Only dissolves in CONC NH3
Halide I-
1) acidify with HNO3 (not HCl due to Cl- ion present in acid!)
2) add AgNO3 - silver nitrate solution
3) add dilute NH3 then conc. NH3 (to double check)
Positive = yellow ppt and insolvable in ammonia
Mg2+
Add NaOH - white ppt
Ass H2SO4 - no change
Ca2+
Brick red flame test
with dilute NaOH - white ppt
With dilute H2SO4 - slight white ppt
Sr2+
Red flame test
with dilute NaOH - no change
With dilute H2SO4 - white ppt
Ba2+
Green flame test
- add dilute NaOH - no change
- dilute H2SO4 - white ppt
NH4+
1) add NaOH
2) heat
3) hold damp red litmus paper at test tube mouth - litmus paper turns from red to blue
Cl2 test
Bleaches damp litmus paper
H2O + Cl2 —> HCl + HOCl
H2 (gas)
- pops with lit splint
Oxygen
Relights glowing splint
Al3+ test
Add aqueous NaOH
White Ppt dissolves in XS
