Qualitative tests

Hydrogen

Hydrogen

Invisible blue flame

1. Insert lit splint into test tube with gas

2. Produces squeaky pop

Oxygen

1. Insert glowing split into test tube with gas

2. Splint will relight

Ammonia

1. Put a piece of damp red litmus paper into the flask

2. The paper goes blue in the presence of ammonia

Chlorine

1. Put a piece of damp blue litmus paper into the flask

2. The paper goes red then white in the presence of chlorine

Carbon Dioxide

1. Bubble the gas through limewater

2. The limewater goes from colorless to cloudy (white ppt) in the presence of CO2

Water

1. Add liquid to white anhydrous copper(II) sulphate

2. If the copper(II) sulphate turns blue, the liquid contains water

3. Test boiling and melting points

Flame test

1. Clean a nichrome wire by dipping it in HCl and heating it a roaring Bunsen flame repeatedly until the wire does not produce a color in the flame

2. moisten the wire with HCl and dip it in the sample to be tested

3. Heat the sample in a roaring Bunsen flame

Ca2+

Brick Red

Na+

Yellow-orange

K+

Lilac

Cu2+ (Flame)

Green

Li+

Crimson/bright red

Precipitate Reactions

Add NaOH solution to solution of sample

Cu2+ (Precipitate)

Blue precipitate

Fe2+

Green precipitate

Fe3+

Brown precipitate (Rust)

Ammonium

1. Heat gently with NaOH

2. Test for gas with damp red litmus paper

3. Litmus paper will turn blue

Silver Halides

Produce insoluble silver halide salts when adding acidified silver nitrate:

1. Add a few drops of dilute nitric acid (HNO3) to the sample (Removes carbonate impurities that would create white precipitate)

2. Add a few drops of silver nitrate solution

Cl-

White precipitate

Br-

Cream precipitate

I-

Yellow Precipitate

SO42-

1. Add dilute HCl

2. Add BaCl2

3. Forms white precipitate

CO32-

1. Add dilute acid

2. Test produced CO2 by bubbling through limewater

3. Turns cloudy