C.8 Identification of Ions and Gases Flashcards
Color seen in flame of lithium
crimson red
Color seen in flame of sodium
orange
Color seen in flame of potassium
lilac
Color seen in flame of calcium
orange - red
Color seen in flame of copper
Green
Formula of lithium ion
Li+
Formula of sodium ion
Na+
Formula of potassium ion
K+
Formula of copper ion
Cu+
Formula of calcium ion
Ca+
Result of calcium (Ca2+) ion in sodium hydroxide solution
- White precipitate of Ca(OH)2 formed
Result of copper (II) (Cu2+) ion in sodium hydroxide solution
- Light blue precipitate formed
Result of Iron (II) (Fe2+) ion in sodium hydroxide solution
- Green precipitate formed
- Starts to change to reddish brown in color after a few minutes
Result of Iron (III) (Fe3+) ion in sodium hydroxide solution
Reddish-brown precipitate formed
Result of zinc in sodium hydroxide solution
- White precipitate formed
- Dissolves in excess sodium hydroxide solution
Formula of sodium hydroxide solution
OH-
Ca2+ + 2OH- –> ?
Ca(OH)2
Cu2+ + 2OH- –> ?
Cu(OH)2
Fe3+ + 2OH- –> ?
Fe(OH)3
Test for halide ions
- Add a small amount of nitric acid – to remove impurities
- Add Silver (I) Nitrate Solution
All halide ions are soluble except for…
Silver halides
Describe the test for chloride ions
To a solution of the chloride ions add:
- Dilute nitric acid
- Silver nitrate solution
Describe the test for bromide ions
To a solution of the chloride ions add:
- Dilute nitric acid
- Silver nitrate solution
Describe the test for Iodide ions
To a solution of the chloride ions add:
- Dilute nitric acid
- Silver nitrate solution
Describe the test for sulfate ions
To a solution of sulfate
ions add:
1. Dilute hydrochloric acid
2. Barium chloride solution
Describe the test for nitrate ions
- Add sodium hydroxide solution and warm
- Add aluminum powder
- Test any gas produced with damp red litmus paper
Result of test for chloride ions
White precipitate (of AgCl)
Result of test for bromide ions
Cream precipitate (of AgBr)
Result of test for iodide ions
Yellow precipitate (of AgI)
Result of test for sulfate ions
White precipitate (of BaSO4)
Result of test for nitrate ions
Red litmus paper goes blue (ammonia gas produced)
Test for carbonates (CO32-)
- Add dilute HCl (hydrochloric acid)
2. Bubble gas through limewater
Result of test for carbonates (CO32-)
- effervescence (as CO2 is produced)
- Limewater turns cloudy
Most metal sulphates are soluble, except for ___
Barium Sulphate
Test for sulphates
Add small amount of HCl (hydrochloric acid)
Add Barium Chloride solution
Results of test for sulphates
- white precipitate of BaSO4 formed
Test for nitrate ions
- Add sodium hydroxide and warm it.
- Reduce it with aluminum powder to produce ammonium ions.
- The ammonium ions then react with the hydroxide to
produce ammonia gas. - Test the ammonia gas with damp red litmus paper. As
ammonia is basic it turns blue.
Test for hydrogen gas (H2)
Hydrogen ignites with oxygen and creates a ‘squeaky pop’ sound
Test for oxygen gas (O2)
Put in a glowing splint
Method of squeaky pop test
Lit splint placed in mouth of test tube, a pop is heard.
Result for test of oxygen gas (O2)
Splint relights if the test tube contains oxygen
gas.
Test for carbon dioxide
Limewater test
Method of limewater test
Pass carbon dioxide gas through limewater (calcium
hydroxide, Ca(OH)2)
Result of test for carbon dioxide (CO2)
Limewater goes cloudy
Test for chlorine gas (Cl2)
Litmus paper test
Result of test for chlorine gas (C2)
Blue litmus paper goes red then white (bleached)
Test for ammonia (NH3)
Dip in red litmus paper
Result of test for ammonia (NH3)
Red litmus paper turns blue and strong smell is produced
What is the cloudiness of limewater caused by?
Insoluble calcium carbonate
Test for ammonium (NH4+)
Sodium hydroxide
Test for copper (II) (Cu2+)
Sodium hydroxide
Test for iron (II) (Fe2+)
Sodium hydroxide
Test for iron (III) (Fe3+)
Sodium hydroxide
Test for zinc (Zn2+)
Sodium hydroxide
Test for Ammonia gas (NH3)
Red litmus paper test
Result of test for Ammonia gas (NH3)
Turns damp red litmus paper blue.
Why acid is added to test for sulfate ions and halide ions?
To remove impurities