Ammonia, NH3 / The test for ammonia gas
2 marks · NormalA student is given a sample of gas and uses a piece of damp red litmus paper to test it.
State the result if the gas is ammonia. Explain why this result is seen.
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The red litmus paper turns blue because ammonia is an alkaline gas.
Also accept: The paper turns blue as ammonia is an alkaline gas.; Turns blue because ammonia makes the litmus paper alkaline.; Red litmus paper goes blue because ammonia has alkaline properties.
Common mistakes: Turns red; No change; Turns white
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Marking points
B1 · 1 mark · Red litmus paper turns blue.
B2 · 1 mark · Ammonia is an alkaline/basic gas / because ammonia makes the environment alkaline.
Worked solution
Ammonia gas turns red litmus paper blue (1 mark) because ammonia is alkaline (1 mark).