Define pH. In the treatment of water for drinking it may be necessary to adjust the pH. Name a substance that is added to the water (i) if the pH is too high, (ii) if the pH is too low. What harm could result if the pH of a drinking water supply was too low? Flocculation and fluoridation are the terms used for two other processes involved in the treatment of water for drinking. In the case of one of these processes, explain how and why it is carried out. The following words/phrases, which all relate to sewage treatment, are omitted from the passage below. biological oxidation eutrophication nitrates & phosphates solids Write in your answer book the omitted word/phrase corresponding to each number (1 to 4). The primary stage of sewage treatment involves the removal of ________ . The remaining liquid waste undergoes ________ during the secondary stage. The levels of ________ are lowered during the tertiary stage to help prevent ________.

Leaving Cert Chemistry Water & Water Analysis: Define pH. In the treatment of

Define pH. In the treatment of water for drinking it may be necessary to adjust the pH - Leaving Cert Chemistry - Question 9 - 2010

Question 9

Define pH. In the treatment of water for drinking it may be necessary to adjust the pH. Name a substance that is added to the water (i) if the pH is too high, (ii) ... show full transcript

Worked Solution & Example Answer:Define pH. In the treatment of water for drinking it may be necessary to adjust the pH - Leaving Cert Chemistry - Question 9 - 2010

Step 1

Define pH.

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Answer

The pH is defined as the negative logarithm of the hydrogen ion concentration:

$pH = - ext{log}_{10} [H^+]$

Step 2

Name a substance that is added to the water (i) if the pH is too high.

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If the pH is too high, sulfuric acid is added to lower the pH.

Step 3

Name a substance that is added to the water (ii) if the pH is too low.

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If the pH is too low, lime (calcium hydroxide) is added to raise the pH.

Step 4

What harm could result if the pH of a drinking water supply was too low?

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If the pH of a drinking water supply is too low, it can lead to corrosion of pipes, potentially resulting in the leaching of harmful metals, such as lead, into the water.

Step 5

Flocculation or Fluoridation

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Flocculation is used to remove impurities from water. A flocculating agent (e.g., aluminium sulfate) is added, which causes fine particles to clump together into larger aggregates or 'clumps'. This process helps remove suspended particles, leading to clearer water.

Step 6

1. The primary stage of sewage treatment involves the removal of ________.

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Solids.

Step 7

2. The remaining liquid waste undergoes ________ during the secondary stage.

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Biological oxidation.

Step 8

3. The levels of ________ are lowered during the tertiary stage.

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Nitrates & phosphates.

Step 9

4. To help prevent ________.

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Eutrophication.

Define pH. In the treatment of water for drinking it may be necessary to adjust the pH - Leaving Cert Chemistry - Question 9 - 2010

Worked Solution & Example Answer:Define pH. In the treatment of water for drinking it may be necessary to adjust the pH - Leaving Cert Chemistry - Question 9 - 2010

Define pH.

Name a substance that is added to the water (i) if the pH is too high.

Name a substance that is added to the water (ii) if the pH is too low.

What harm could result if the pH of a drinking water supply was too low?

Flocculation or Fluoridation

1. The primary stage of sewage treatment involves the removal of ________.

2. The remaining liquid waste undergoes ________ during the secondary stage.

3. The levels of ________ are lowered during the tertiary stage.

4. To help prevent ________.

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