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10 (a) Some acids are used in tests for ions - Edexcel - GCSE Chemistry - Question 10 - 2022 - Paper 1
Question 10
10 (a) Some acids are used in tests for ions. A bottle of one acid is shown in Figure 17. (i) The acid in Figure 17 can be used in the test for carbonate ions. Expl... show full transcript
Worked Solution & Example Answer:10 (a) Some acids are used in tests for ions - Edexcel - GCSE Chemistry - Question 10 - 2022 - Paper 1
Step 1
Explain, giving the name of the hazard symbol shown, what safety precautions should be taken when using this acid.
Answer
The hazard symbol shown on the acid in Figure 17 is likely a corrosive symbol. Safety precautions include wearing appropriate personal protective equipment (PPE) such as gloves and goggles to protect the skin and eyes. Additionally, it is important to work in a well-ventilated area or a fume hood to avoid inhaling any harmful fumes, and to have a neutralizing agent and emergency wash station available in case of spills.
Step 2
Step 3
Step 4
Explain an improvement that needs to be made to step 3 to enable a bright flame colour to be produced.
Answer
An improvement to step 3 would be to ensure that the flame test wire is not too far away from the Bunsen burner flame, as holding it too high can result in insufficient heat to produce a bright flame. Also, ensuring the wire is clean from previous samples will prevent contamination that can affect the brightness of the flame.
Step 5
Use Figure 18 to identify the metal ions in compounds P, Q and R.
Answer
From Figure 18:
- Compound P: This corresponded to a red flame, indicating the presence of lithium ions.
- Compound Q: This produced a lilac flame, indicating the presence of potassium ions.
- Compound R: A blue-green flame was observed, indicating the presence of copper ions.
Step 6
Calculate the mass of hydrogen chloride in the acid used to test 20 samples.
Answer
To find the mass of hydrogen chloride in the acid used, first calculate the mass per 5.00 cm³ of acid. The volume of 1.00 dm³ is 1000 cm³ and contains 2199 g of hydrogen chloride, so:
Mass of HCl in 1 cm³ = ( \frac{2199\ g}{1000\ cm³} = 2.199\ g/cm³ )
For 5.00 cm³:
Mass of HCl in 5.00 cm³ = ( 5.00\ cm³ \times 2.199\ g/cm³ = 10.995\ g )
Thus, the total mass for 20 samples is:
Total mass = ( 20 \times 10.995\ g = 219.90\ g )