A student carried out a test to detect sulfate ions in an unknown solution. They added dilute hydrochloric acid to the sample, followed by a few drops of barium chloride solution. A white precipitate formed.
Why is it necessary to add dilute hydrochloric acid before adding the barium chloride solution?
To catalyze the reaction between barium and sulfate ions
To ensure that any carbonate ions present are removed
Chloride ions are required to form the white precipitate
The test only works effectively in alkaline conditions
Practise Edexcel GCSE Chemistry Qualitative analysis: tests for ions with exam-style questions for Foundation and Higher tier. 127 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
