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GCSE Chemistry · key term
Paper containing a coloured indicator that responds to acidic or alkaline conditions.
Used by AQA and Edexcel
Specification 4.8.2.4 · Paper 2
Revise: Test for ChlorineTo test whether a gas is chlorine, dampen a piece of litmus paper with a few drops of water and place the damp end in the gas. A positive result is that the litmus paper is bleached and turns white. Either red or blue litmus paper can be used.
Specification 6.8 · Paper 2
A coloured indicator on paper that changes colour in acidic or alkaline conditions.
Revise: Chemical Test for ChlorineTo test whether a gas is chlorine, moisten a piece of blue litmus paper with a few drops of water so that it is damp, not soaking wet. Hold the damp end in the gas, for example at the opening of a test tube containing the gas. If chlorine is present, the paper is bleached white.
State that the litmus paper must be damp; writing only “litmus paper” gives an incomplete test.
Give both the test and the positive result: place damp litmus paper in the gas, and it is bleached white.
Do not confuse chlorine with ammonia: ammonia turns damp red litmus paper blue, whereas chlorine bleaches damp litmus paper white.
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