Tests are used to identify ions in three salts X, Y and Z - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Question 2
Tests are used to identify ions in three salts X, Y and Z.
(a) (i) In a flame test salt X gives a yellow flame.
What is the metal ion in salt X?
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Worked Solution & Example Answer:Tests are used to identify ions in three salts X, Y and Z - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Step 1
What is the metal ion in salt X?
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Answer
The metal ion in salt X is sodium, Na⁺, as it produces a yellow flame during the flame test.
Step 2
Describe how a flame test is carried out on a solid.
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Answer
To carry out a flame test on a solid, first, a small amount of the solid sample is taken on the end of a clean platinum or metal wire. The wire is then heated in a Bunsen burner flame until no color is imparted to the flame. After this, the sample is introduced into the flame and the color of the flame is observed. The specific color produced by the metal ion can be matched to known standards.
Step 3
Describe what you would see when the barium chloride solution is added.
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Answer
When barium chloride solution is added to the mixture containing salt Y (sulfate), a white precipitate of barium sulfate (BaSO₄) is formed, which indicates the presence of sulfate ions.
Step 4
Describe what is seen when sodium hydroxide solution is added to a solution of Z.
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Answer
When sodium hydroxide solution is added to the solution of salt Z containing iron(III) ions, a reddish-brown precipitate of iron(III) hydroxide (Fe(OH)₃) is observed.
