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 that gives a yellow flame during a flame test is sodium, Na⁺, as sodium salts are known for producing a characteristic bright yellow color.
Step 2
Describe how a flame test is carried out on a solid.
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Answer
To perform a flame test on a solid, first, you need to clean the platinum wire loop by dipping it in hydrochloric acid and then holding it in the flame until it burns without any color. Next, you take a small amount of the solid sample using the cleaned wire loop and place it into the flame. Observe the color of the flame produced—this indicates the presence of specific metal ions.
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 of salt Y (a sulfate) and dilute hydrochloric acid, a white precipitate of barium sulfate, BaSO₄, will form, indicating 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 a solution of salt Z containing iron(III) ions, a reddish-brown precipitate of iron(III) hydroxide, Fe(OH)₃, is formed, indicating the presence of iron(III) ions.
