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4 (a) (i) Give the name of a carbonate in scale - AQA - GCSE Chemistry - Question 4 - 2014 - Paper 3
Question 4
4 (a) (i) Give the name of a carbonate in scale. 4 (a) (ii) When acids react with scale a gas is produced. What is the name of the gas? 4 (b) Ethanoic acid is us... show full transcript
Worked Solution & Example Answer:4 (a) (i) Give the name of a carbonate in scale - AQA - GCSE Chemistry - Question 4 - 2014 - Paper 3
Step 1
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Step 4
4 (c) (i) Explain why hydrochloric acid reacts faster than ethanoic acid.
Answer
Hydrochloric acid (HCl) is a strong acid, which means it ionizes completely in solution and produces a higher concentration of hydrogen ions (H⁺) compared to ethanoic acid, which is a weak acid. This higher concentration of ions allows hydrochloric acid to react more quickly with scale.
Step 5
4 (c) (ii) Suggest why hydrochloric acid should not be used to dissolve scale in kettles.
Answer
Hydrochloric acid is corrosive, and using it to dissolve scale in kettles can damage the kettle's material, especially if it is made of metal. It can lead to deterioration and leakage over time.
Step 6
4 (d) Calculate the concentration of the hydrochloric acid.
Answer
To calculate the concentration of the hydrochloric acid, we can use the information provided in the titration:
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Determine moles of NaOH used:
Moles = Concentration × Volume = 0.200 mol/dm³ × (28.60 cm³ × 1 dm³/1000 cm³) = 0.00572 moles
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The reaction between HCl and NaOH is a 1:1 ratio, hence moles of HCl = moles of NaOH = 0.00572 moles.
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Now, to find the concentration of HCl:
Concentration = Moles/Volume = 0.00572 moles / (25.00 cm³ × 1 dm³/1000 cm³) = 0.2288 mol/dm³.
Thus, the concentration of the hydrochloric acid is 0.2288 mol/dm³.