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This question is about water - AQA - GCSE Chemistry - Question 4 - 2016 - Paper 3
Question 4
This question is about water. Hard water contains dissolved compounds. Explain one benefit of drinking hard water. What is the name of the solid formed when hard w... show full transcript
Worked Solution & Example Answer:This question is about water - AQA - GCSE Chemistry - Question 4 - 2016 - Paper 3
Step 1
Explain one benefit of drinking hard water.
Answer
One benefit of drinking hard water is that it provides essential minerals, particularly calcium ions, which are important for the development and maintenance of strong bones and teeth. Additionally, consuming hard water may lower the risk of heart disease due to its calcium content.
Step 2
Step 3
Describe how this happens.
Answer
Temporary hard water contains dissolved calcium hydrogen carbonate (or hydrogen carbonate ions). When heated in an electric kettle, these compounds decompose, producing a precipitate. This process forms calcium carbonate, which can coat the heating element and reduce its efficiency by preventing proper heat transfer to the water.
Step 4
Explain how an ion exchange resin changes the dissolved compounds in tap water to improve the water.
Answer
Ion exchange resins typically contain sodium or hydrogen ions, which can replace or remove calcium and magnesium ions from tap water. This exchange helps to reduce the hardness of the water, producing what's known as soft water, which can be beneficial for various household applications, including preventing scale build-up in appliances.