(a) (i) What is hard water?
(ii) What type of water hardness can be removed by boiling?
(iii) Name, or give the formula, of a substance that causes this type of water hardness - Leaving Cert Chemistry - Question 7 - 2018
Question 7
(a) (i) What is hard water?
(ii) What type of water hardness can be removed by boiling?
(iii) Name, or give the formula, of a substance that causes this type of ... show full transcript
Worked Solution & Example Answer:(a) (i) What is hard water?
(ii) What type of water hardness can be removed by boiling?
(iii) Name, or give the formula, of a substance that causes this type of water hardness - Leaving Cert Chemistry - Question 7 - 2018
Step 1
What is hard water?
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Answer
Hard water is water that contains dissolved calcium (Ca²⁺) and magnesium (Mg²⁺) ions. It leads to the formation of scale and makes it difficult for soap to lather.
Step 2
What type of water hardness can be removed by boiling?
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Answer
Temporary hardness is the type of water hardness that can be removed by boiling. This form of hardness is primarily caused by bicarbonates of calcium and magnesium.
Step 3
Name, or give the formula, of a substance that causes this type of water hardness.
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Answer
The compound responsible for temporary hardness is calcium bicarbonate, which can be represented by the formula: Ca(HCO3)2.
Step 4
Identify a problem caused by hard water.
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One significant problem caused by hard water is the formation of scale in pipes and on appliances, which can reduce efficiency and increase energy consumption.
Step 5
What is flocculation?
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Flocculation refers to the process of agglomerating suspended particles in water to form larger particles (flocs) that can be removed through filtration.
Step 6
Give the purpose of sand and gravel in water purification.
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Sand and gravel are used in water purification to facilitate the mechanical filtration process. They provide a substrate for the settling of suspended materials, thus improving water clarity.
Step 7
What is the purpose of adding chlorine to the water supply?
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Chlorine is added to drinking water to kill microorganisms and pathogens that can cause illness, ensuring that the water is safe for consumption.
Step 8
Why is NaF added to the water?
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NaF is added to water to help prevent tooth decay as it strengthens the enamel of the teeth.
Step 9
Under what circumstance would lime (CaO) be added to the water supply?
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Lime (CaO) would be added to the water supply to increase the pH level and neutralize acidity, promoting a suitable environment for water treatment processes.
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