Ammonia, NH3 / The test for ammonia gas
3 marks · EasyA student tested three samples of gas (A, B, and C) using damp red litmus paper. Their results are recorded in the table below.
| Sample | Observation |
|---|---|
| A | Red litmus paper turns blue |
| B | No change |
| C | Red litmus paper turns white |
Identify the sample that contains ammonia.
Give a reason for your answer to part (a).
Suggest the gas that could be present in sample C.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Sample A
(b) Because ammonia turns red litmus paper blue.
(c) Chlorine
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies Sample A as containing ammonia.
B1 (b) · 1 mark · Gives the correct reason (ammonia turns red litmus blue).
B1 (c) · 1 mark · Suggests chlorine as the gas that turns red litmus white.
Worked solution
(a) Sample A contains ammonia.
(b) Ammonia turns red litmus paper blue.
(c) Sample C could contain chlorine gas (which bleaches litmus paper).