Edexcel A-Level Chemistry A2 17.12 H2o Oh and Nh3 Act As Monodentate Ligands Questions

Practise Edexcel IAL Chemistry 17.12 by recognising H2O, OH- and NH3 as monodentate electron-pair donors that form one dative bond to a central metal ion.

Exam points

Explain monodentate as forming one dative bond through one donated lone pair.
Recognise H2O, OH- and NH3 as electron-pair donors in complex-ion formation.

[Maximum number: 2]

This question is about compounds and complex ions of iron.

In aqueous solution, iron(II) exists as the complex ion $\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ .

Explain how water acts as a monodentate ligand.

An explanation that makes reference to the following points:

- because it forms one dative (covalent) / co-ordinate bond (to $\mathrm{Fe}^{2+}$ )

(1)

- using a lone pair (of electrons) on oxygen

(1)

Allow 'a dative/co-ordinate bond'

Allow oxygen donates a pair of electrons Ignore water uses a lone pair of electrons COMMENT

Allow M2 for a diagram showing the oxygen lone pair forming the co-ordinate bond but annotation needed to score M1

(2)

Number

Admer

T

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Edexcel A-Level Chemistry A2 17.12 H2o Oh and Nh3 Act As Monodentate Ligands Questions question 1