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1 markWater

CAPE Chemistry Unit 2 · 2007 · Paper 2 · Question 3(a)(ii)

Phosphate levels above 0.5 - 1.0 mg dm^-3 in freshwater bodies indicate pollution.

What observable feature of a polluted lake could result from phosphate concentrations above 1.0 mg dm^-3?

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Other parts of this question

  1. 3(a)(i)Suggest ONE possible source of phosphate ions found in polluted rivers and lakes.[1 mark]
  2. 3(a)(iii)What process is responsible for the observed feature resulting from high phosphate levels?[1 mark]
  3. 3(b)(i)Using the calibration curve of absorbance versus concentration provided in Figure 1, estimate the concentration of phosphate ion in each sample and complete…[4 marks]
  4. 3(b)(ii)Calculate the average concentration of PO4^3- found in the three samples.[2 marks]
  5. 3(b)(iii)Based on the results of the analysis, determine whether the concentration of PO4^3- is within acceptable limits.[1 mark]

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