V Chemistry - Chemical Tests

Li+ (2 points)

• Flame Test

• Crimson-red flame

Na+ (2 points)

• Flame Test

• Yellow flame

K+ (2 points)

• Flame test

• Lilac flame

Ca2+ (2 points)

• Flame test

• Orange-red flame

Cu2+ (2 tests, 2 points each)

• Flame test

• Blue-green flame

OR

• Add sodium hydroxide

• Blue precipitate forms

NH4+ (3 points)

• Add sodium hydroxide

• Test with damp red litmus

• Litmus turns blue

Fe2+ (2 points)

• Add sodium hydroxide

• Green precipitate forms

Fe3+ (2 points)

• Add sodium hydroxide

• Brown precipitate forms

Cl- (3 points)

• Add nitric acid

• Add silver nitrate

• White precipitate forms

Br- (3 points)

• Add nitric acid

• Add silver nitrate

• Cream precipitate forms

I- (3 points)

• Add nitric acid

• Add silver nitrate

• Yellow precipitate forms

SO42- (3 points)

• Add hydrochloric acid

• Add barium chloride

• White precipitate forms

CO32- (3 points)

• Add hydrochloric acid

• Bubble through lime water

• Turns cloudy white

H2 (2 points)

• Test with lit splint

• Hear a ‘squeaky pop’ sound

O2¬ (2 points)

• Test with glowing splint

• Splint will relight

CO2 (2 points)

• Bubble through lime water

• Turns cloudy-white

NH3 (2 points)

• Test with damp red litmus

• Litmus turns blue

Describe the procedure involved when carrying out a flame test.

• Use nichrome wire (made of platinum)

• Dip in hydrochloric acid

• Dip in solid/solution being tested

• Place in non-luminous (blue) flame

Why is acid added before testing for halides?

• To remove carbonate (or hydroxide) ions

Why is hydrochloric acid not used for testing halides?

• Chloride ions in hydrochloric acid will cause a fake positive result

What is the name and formula of the solute in a solution of limewater?

• Calcium hydroxide

• Ca(OH)2

Water

• Add solution to anhydrous copper sulfate

• Anhydrous copper sulfate will turn blue

Pure Water

• Test boiling and freezing point

• Pure water will boil at 100 degrees C

• Pure water will freeze at 0 degrees C