2.44: Describe the Tests for these Gases: Hydrogen, Oxygen, Carbon Dioxide, Ammonia and Chlorine

TEST FOR HYDROGEN:

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HYDROGEN TEST

Diagram showing the Test for Hydrogen

METHOD: Collect gas into a boiling tube Insert lit Splint inside the boiling tube

RESULT: If Hydrogen is present, the gas will burn with a ‘squeaky pop’

EQUATION: 2H2 (g)    +    O2 (g)     →     2H2O (l)

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TEST FOR OXYGEN:

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OXYGEN TEST

Diagram showing the Test for Oxygen

METHOD: Collect gas into a boiling tube Insert glowing splint

RESULT: If Oxygen is present, splint will relight

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TEST FOR CARBON DIOXIDE:

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CARBON DIOXIDE TEST

Diagram showing the Test for Oxygen

METHOD: Bubble gas through limewater Observe colour change

RESULT: If Carbon Dioxide is present, limewater will turn milky and cloudy

EQUATION: Ca(OH)2 (aq)    +    CO2 (g)     →     CaCO3 (s)     +    H2O (l) *White Solid - CaCO3, turns limewater Milky

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TEST FOR AMMONIA:

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AMMONIA TEST

Diagram showing the Test for Ammonia

METHOD: Lower damp red litmus paper or damp universal indicator paper into test solution

RESULT: If Ammonia is present, damp red litmus paper turns Blue If Ammonia is present, damp universal indicator paper turns Purple

EQUATION: NH3 (g)    +    H2O (l)     →     NH4+ (aq)     +    OH- (aq) *Hydroxide ions - OH-, turns litmus Blue

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TEST FOR CHLORINE:

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CHLORINE TEST

Diagram showing the Test for Chlorine

METHOD: Lower damp litmus paper or moist starch-iodide paper into test solution

RESULT: If Chlorine is present, damp litmus paper is bleached White If Chlorine is present, moist starch-iodide paper turns Blue

EQUATION FOR MOIST STARCH - IODIDE PAPER: Cl2 (g)    +    2l- (aq)     →     2Cl- (aq)     +    I2 (aq) *Iodine formed turns the starch Blue