10.1.5

Required Practical: Analysing and Purifying Water

Test yourself

Method 1: Analysing Water Samples (PH and Dissolved Solids)

This experiment aims to test water samples from different sources for pH and dissolved solids.

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Apparatus

  • Water samples (A, B, C, D)
  • Universal indicator paper or pH meter
  • Evaporating basin
  • Mass balance
  • Measuring cylinder
  • Bunsen burner
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Method

  • Use a universal indicator or a pH meter to measure the pH of each water sample.
  • Weigh an empty evaporating basin accurately.
  • Add 25 cm3 of the water sample to the basin.
  • Heat gently over a Bunsen burner until most of the water evaporates.
  • Once cooled, reweigh the basin and calculate the mass of solid left behind.
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Reminders

  • Avoid overheating:
    • Some solids may decompose, giving false results.
  • The mass of residue shows how much dissolved solids the water contained.
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Analysis

  • Compare pH and solid content between samples.
  • High solid content or very low pH suggests poorer water quality.
  • Results can indicate where the water might have come from:
    • For example, the sea, river, rain
  • Compare results to safe drinking water standards.
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Hazards and precautions

  • Acidic or alkaline water samples:
    • Some samples may cause irritation to the eyes or skin.
    • Rinse immediately if contact occurs.
  • Heated apparatus:
    • Touching hot apparatus may cause burns.
    • Allow them to cool before holding.

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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