A student carried out a flame test on a sample of solid potassium chloride - Edexcel - GCSE Chemistry - Question 10 - 2023 - Paper 2
Question 10
A student carried out a flame test on a sample of solid potassium chloride.
The student followed this method.
step 1 dip a dry wooden splint into water
step 2 then... show full transcript
Worked Solution & Example Answer:A student carried out a flame test on a sample of solid potassium chloride - Edexcel - GCSE Chemistry - Question 10 - 2023 - Paper 2
Step 1
Explain one improvement that the student could make to their method to obtain a valid conclusion.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One improvement that the student could make is to use a clean wooden splint for each test. This would prevent contamination from any previous tests, ensuring that the results are accurate and reflective of the sample being tested.
Step 2
What colour should the student have seen in the flame if the test had been carried out correctly?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The student should have seen a lilac colour (Option B) in the flame if the test had been carried out correctly, as potassium ions produce this distinctive colour during a flame test.
Step 3
Describe the test for chloride ions.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To test for chloride ions, a small amount of the sample is dissolved in water to create a solution. Then, a few drops of dilute nitric acid followed by a few drops of silver nitrate solution are added. If chloride ions are present, a white precipitate of silver chloride will form.
Step 4
Calculate the mass of barium chloride that must be dissolved in water to make 25 cm³ of solution of this concentration.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To find the mass of barium chloride needed, we can use the formula:
Mass = Concentration × Volume.
Firstly, convert the volume from cm³ to dm³:
25 cm³ = 0.025 dm³.
Now, using the concentration of 83 g dm⁻³:
Mass = 83 g dm⁻³ × 0.025 dm³ = 2.075 g.
Rounding to 2 significant figures, the mass of barium chloride required is approximately 2.1 g.
Step 5
Write the ionic equation for this reaction.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The ionic equation for the reaction between barium chloride and aluminium sulfate is:
