1 (a) Rainwater is soft water - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 3
Question 1
1 (a) Rainwater is soft water.
How is hard water formed from rainwater?
1 (b) A sample of hard water contains magnesium sulfate.
Figure 1 shows the solubility of ma... show full transcript
Worked Solution & Example Answer:1 (a) Rainwater is soft water - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 3
Step 1
How is hard water formed from rainwater?
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Answer
Hard water is formed when rainwater absorbs minerals, particularly calcium and magnesium ions, as it flows over geological formations such as limestone, allowing these ions to dissolve into the water.
Step 2
What conclusions can be made from Figure 1?
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Answer
From Figure 1, we can conclude that the solubility of magnesium sulfate increases with temperature up to approximately 68°C, where it reaches a maximum solubility of 59 grams per 100 grams of water. Beyond this temperature, the solubility begins to decrease, indicating a temperature-sensitive behavior of magnesium sulfate in water.
Step 3
Give one advantage and one disadvantage of hard water.
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Advantage: Hard water is beneficial for bones and teeth due to its mineral content.
Disadvantage: Hard water can lead to the formation of scale in heating systems and kettles, reducing their efficiency.
Step 4
Describe and explain how hard water is softened using an ion exchange column.
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An ion exchange column contains resin that is charged with sodium or hydrogen ions. When hard water passes through the column, magnesium and calcium ions in the water are exchanged for sodium or hydrogen ions in the resin. This process effectively removes the hardness from the water, resulting in softened water that no longer contains calcium or magnesium ions.
