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 (X) in the box next to your answer.
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Answer
The yellow precipitate formed when silver nitrate solution was added indicates the presence of chloride ions (Cl⁻) in the salt. Therefore, the correct answer is B, chloride, Cl⁻.
Step 2
Explain how the technician should do this.
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Answer
To identify which bottle contains the sodium salt and which contains the potassium salt, the technician can carry out a flame test. A small amount of each salt can be placed in a flame; sodium will produce a bright yellow flame while potassium will produce a lilac flame. This distinctive coloration will help in identifying which salt is present in each bottle.
Step 3
Describe what you would see when these solutions are mixed.
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Answer
When sodium hydroxide solution is mixed with a solution containing copper ions (Cu²⁺), a blue precipitate of copper(II) hydroxide (Cu(OH)₂) is formed. The formation of this precipitate can be observed as a cloudy blue solution.
Step 4
Write the ionic equation for this reaction.
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Answer
The ionic equation for the reaction between sodium hydroxide and copper(II) ions is:
Cu2++2OH−→Cu(OH)2
