[Co(NH₃)₆]^{3+} + 3HNCH₂CH₂NH₂ → [Co(HNCH₂CH₂NH₂)₃]^{3+} + 6NH₃
Which statement is correct about this reaction?
A - AQA - A-Level Chemistry - Question 26 - 2018 - Paper 3
Question 26
[Co(NH₃)₆]^{3+} + 3HNCH₂CH₂NH₂ → [Co(HNCH₂CH₂NH₂)₃]^{3+} + 6NH₃
Which statement is correct about this reaction?
A. The co-ordination number of cobalt decreases.
B... show full transcript
Worked Solution & Example Answer:[Co(NH₃)₆]^{3+} + 3HNCH₂CH₂NH₂ → [Co(HNCH₂CH₂NH₂)₃]^{3+} + 6NH₃
Which statement is correct about this reaction?
A - AQA - A-Level Chemistry - Question 26 - 2018 - Paper 3
Step 1
A. The co-ordination number of cobalt decreases.
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Answer
This statement is incorrect because the coordination number of cobalt remains the same as the original complex, which is 6.
Step 2
B. The enthalpy change is large and positive.
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Answer
This statement is also incorrect. The enthalpy change for this reaction is not necessarily large and positive as it involves the formation of a more stable complex.
Step 3
C. The entropy change is large and positive.
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Answer
This statement is correct. The reaction produces a smaller number of moles of gaseous products (NH₃) and causes an increase in disorder because the three ligands replace six NH₃ molecules. Hence, there is a significant increase in entropy.
Step 4
D. The shape of the complex changes from octahedral.
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Answer
This statement is incorrect. The shape of the cobalt complex remains octahedral following the substitution reaction.
![[Co(NH₃)₆]^{3+}-+-3HNCH₂CH₂NH₂-→-[Co(HNCH₂CH₂NH₂)₃]^{3+}-+-6NH₃--Which-statement-is-correct-about-this-reaction?--A-AQA-A-Level Chemistry-Question 26-2018-Paper 3.png](https://cdn.simplestudy.io/assets/backend/uploads/question/Question_26_2018_Chemistry_P3.jpg)
