Testing for chlorides (Cl^-), bromides (Br^-) and iodides (I^-)
2 marks · EasyA student adds silver nitrate solution to acidified solutions of three unknown salts. She observes the following: - Salt A: forms a white precipitate - Salt B: forms a cream precipitate - Salt C: forms a yellow precipitate Calculate the number of different halide ions identified and state the expected observation for each positive test.
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.
Show answer
Three different halide ions (chloride, bromide, iodide); white for chloride, cream for bromide, yellow for iodide.
Also accept: 3; white (chloride), cream (bromide), yellow (iodide)
Common mistakes: Mixing up the colours; Stating a wrong number of halides
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Gives the number of different halide ions: 3
B2 · 1 mark · States the correct observation for each: white for chloride, cream for bromide, yellow for iodide (all or nothing for colour/ion match)
Worked solution
There are 3 different halide ions: - Chloride gives a white precipitate - Bromide gives a cream precipitate - Iodide gives a yellow precipitate