Potash alum is a chemical compound - AQA - GCSE Chemistry - Question 7 - 2021 - Paper 2
Question 7
Potash alum is a chemical compound.
The formula of potash alum is KAl(SO₄)₂
07.1 Give a test to identify the Group 1 metal ion in potash alum.
You should include th... show full transcript
Worked Solution & Example Answer:Potash alum is a chemical compound - AQA - GCSE Chemistry - Question 7 - 2021 - Paper 2
Step 1
Give a test to identify the Group 1 metal ion in potash alum.
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Answer
To identify the Group 1 metal ion in potash alum, perform a flame test. A small amount of the sample can be introduced to a flame using a clean wire loop.
The result is that the flame will show a lilac color, which indicates the presence of potassium ion.
Step 2
Name one instrumental method that could identify the Group 1 metal ion and show the concentration of the ion in a solution of potash alum.
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Answer
One instrumental method to identify the Group 1 metal ion and show the concentration is flame emission spectroscopy.
Step 3
Give the result of this test.
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Answer
The result of adding sodium hydroxide solution to the potash alum will produce a white precipitate.
Step 4
What additional step is needed so that the other metal ion in potash alum can be identified?
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An additional step needed is to add excess sodium hydroxide solution, which will help in precipitating the other ions present.
Step 5
Give the result of this additional step.
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The result of this additional step is that the precipitate may dissolve, indicating the presence of the other ion.
Step 6
Describe a test to identify the presence of sulfate ions in a solution of potash alum.
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To test for sulfate ions, add barium chloride solution to the potash alum solution. A white precipitate will form if sulfate ions are present.
