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.
Ex... 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
The acid in Figure 17 can be used in the test for carbonate ions.
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Answer
The acid shown in Figure 17 is nitric acid (HNO₃). The hazard symbol typically associated with nitric acid is the corrosive symbol. When using this acid, it is essential to wear safety goggles, gloves, and a lab coat to prevent skin and eye contact, and to work in a well-ventilated area or fume hood to avoid inhalation of harmful fumes.
Step 2
Give the name of the acid shown in Figure 17.
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Answer
The acid shown in Figure 17 is nitric acid.
Step 3
State a property of glass that makes it a suitable material to make the container for an acid.
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Answer
One important property of glass is its chemical inertness, meaning it does not react with acids, making it a safe material for storing corrosive substances like acids.
Step 4
Explain an improvement that needs to be made to step 3 to enable a bright flame colour to be produced.
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Answer
To improve the flame test, the teacher should ensure that the flame test wire is thoroughly cleaned between tests to prevent contamination and ensure a clear, bright flame color.
Step 5
Use Figure 18 to identify the metal ions in compounds P, Q and R.
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Answer
Based on the results shown in Figure 18:
Compound P is identified as lithium, producing a red flame.
Compound Q corresponds to potassium, which gives a lilac flame.
Compound R indicates the presence of copper, resulting in a blue-green flame.
Step 6
Calculate the mass of hydrogen chloride in the acid used to test 20 samples.
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Answer
To find the mass of hydrogen chloride in the acid used for testing, first calculate the total volume of acid used:
5.00 cm³ × 20 = 100.00 cm³ = 0.100 dm³.
Now, using the concentration given (1.00 dm³ contains 2199 g of HCl), we can use the formula:
extmass=extvolumeimesextdensity
Thus,
extmass=0.100extdm3imes2199extg/1extdm3=219.9extg
So, the mass of hydrogen chloride in the acid used to test 20 samples is approximately 220 g.
