Testing for gases
HYDROGEN
A lighted wooden splint makes a popping sound in a test tube of hydrogen.
OXYGEN
A glowing wooden splint relights in a test tube of oxygen.
CARBON DIOXIDE
Carbon dioxide turns limewater milky. A lighted wooden splint goes out in a test tube of carbon
dioxide but this happens with other gases, too. So the limewater test is a better choice.
AMMONIA
Ammonia has a characteristic sharp, choking smell. It also makes damp red litmus paper turn
blue. Ammonia forms a white smoke of ammonium chloride when hydrogen chloride gas, from
concentrated hydrochloric acid, is held near it.
Summary questions
1) Explain why hydrogen gas ‘pops’ when a lighted splint is applied?
Because hydrogen is highly ammable
2)
a. Write a word equation for the reaction of magnesium carbonate plus dilute sulphuric acid
which produces carbon dioxide gas
Magnesium carbonate + sulphuric acid → Carbon dioxide+ Magnesium sul te + water
b. -
3) during electrolysis of a chloride solution, a student predicted that a mixture of chloride and
oxygen would be given o from the anode. Describe how you can test this prediction
By inserting a glowing wooden splint and see whether it lights or not
4)
a.
I - magnesium and dilute hydrochloric acid to produce hydrogen gas.
Magnesium + sulphuric acid → Magnesium sulphite + hydrogen
II - write an ionic equation
b. —
5) —-
ff fl fi
HYDROGEN
A lighted wooden splint makes a popping sound in a test tube of hydrogen.
OXYGEN
A glowing wooden splint relights in a test tube of oxygen.
CARBON DIOXIDE
Carbon dioxide turns limewater milky. A lighted wooden splint goes out in a test tube of carbon
dioxide but this happens with other gases, too. So the limewater test is a better choice.
AMMONIA
Ammonia has a characteristic sharp, choking smell. It also makes damp red litmus paper turn
blue. Ammonia forms a white smoke of ammonium chloride when hydrogen chloride gas, from
concentrated hydrochloric acid, is held near it.
Summary questions
1) Explain why hydrogen gas ‘pops’ when a lighted splint is applied?
Because hydrogen is highly ammable
2)
a. Write a word equation for the reaction of magnesium carbonate plus dilute sulphuric acid
which produces carbon dioxide gas
Magnesium carbonate + sulphuric acid → Carbon dioxide+ Magnesium sul te + water
b. -
3) during electrolysis of a chloride solution, a student predicted that a mixture of chloride and
oxygen would be given o from the anode. Describe how you can test this prediction
By inserting a glowing wooden splint and see whether it lights or not
4)
a.
I - magnesium and dilute hydrochloric acid to produce hydrogen gas.
Magnesium + sulphuric acid → Magnesium sulphite + hydrogen
II - write an ionic equation
b. —
5) —-
ff fl fi
