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3 (a) Give the name or the formula of an ion that causes hardness in water - Edexcel - GCSE Chemistry - Question 3 - 2017 - Paper 1
Question 3
3 (a) Give the name or the formula of an ion that causes hardness in water. (b) A, B and C are samples of hard water from three different sources. A 10 cm³ sample ... show full transcript
Worked Solution & Example Answer:3 (a) Give the name or the formula of an ion that causes hardness in water - Edexcel - GCSE Chemistry - Question 3 - 2017 - Paper 1
Step 1
Step 2
3 (b) Explain, using the information in the table, the types of hardness in each of the hard waters A, B and C.
Answer
From the table provided:
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Water Sample A: Before boiling, it required 10.2 cm³ of soap solution, indicating high temporary hardness due to the presence of bicarbonate ions. After boiling, it required only 0.1 cm³, suggesting that the bicarbonates were removed by boiling, converting it to permanent hardness.
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Water Sample B: It required the same amount of soap solution both before and after boiling (20.0 cm³). This indicates that it possesses permanent hardness due to the presence of ions such as sulfates or chlorides that do not get removed by boiling.
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Water Sample C: It initially required the most soap solution (35.3 cm³) before boiling, indicating it has high temporary hardness. After boiling, it still required 12.2 cm³ of soap solution, which suggests that it also contains permanent hardness, making it a combination of both types.