A technician had two bottles containing solid salts - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Question 2
A technician had two bottles containing solid salts.
One bottle contained a potassium salt and the other contained a sodium salt.
Unfortunately the labels had fallen... show full transcript
Worked Solution & Example Answer:A technician had two bottles containing solid salts - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Step 1
Complete the sentence by putting a cross (✗) in the box next to your answer.
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Answer
The test shows the anion in the salt is C iodide, I⁻. This is because the formation of a yellow precipitate indicates the presence of iodide when tested with silver nitrate.
Step 2
Explain how the technician should do this.
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Answer
To differentiate between the sodium and potassium salts, the technician can carry out a flame test. When heated over a flame, sodium ions produce a bright yellow flame, while potassium ions produce a lilac flame. This way, the technician can identify which bottle contains which salt.
Step 3
Describe what you would see when these solutions are mixed.
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Answer
When sodium hydroxide solution is mixed with copper ions, a blue precipitate of copper(II) hydroxide, Cu(OH)₂, is observed. The solution changes from clear to cloudy blue.
Step 4
Write the ionic equation for this reaction.
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Answer
The ionic equation for this reaction is:
Cu2++2OH−→Cu(OH)2
