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3 marksFirst Row Transition Elements

CAPE Chemistry Unit 1 · 2021 · Paper 2 · Question 3(c)(i)

When concentrated HCl is added to a pink solution of cobalt(II) chloride, the solution turns blue.

Explain the observation in terms of the stability constant of the complex ion formed.

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Other parts of this question

  1. 3(a)(i)Complete Table 2 by inserting the missing electronic structure (ES) and the oxidation state (OS) for EACH element listed.[5 marks]
  2. 3(a)(ii)Explain the difference between the trend of the first ionization energy for the Group II elements and the first row transition elements.[4 marks]
  3. 3(b)(i)Account for the difference in oxidation state between vanadium and calcium.[4 marks]
  4. 3(b)(ii)Comment on the observation that calcium carbonate is more thermally stable than magnesium carbonate.[2 marks]
  5. 3(c)(ii)Write a balanced equation for the reaction occurring when concentrated HCl is added to a pink solution of cobalt(II) chloride.[2 marks]
  6. 3(d)(i)Complete Table 3 to show the observations expected for EACH of the tests on ammonium vanadate.[5 marks]
  7. 3(d)(ii)Write the formula of the species formed which is responsible for EACH colour observed in (d)(i) in Table 3.[5 marks]

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