Figure 3 shows some reactions of aqueous iron ions - AQA - A-Level Chemistry - Question 4 - 2019 - Paper 1
Question 4
Figure 3 shows some reactions of aqueous iron ions.
Solution containing
Complex ion L
Reaction 1
Na2CO3(aq) → Precipitate J
Reaction 2
Concentrated HCl(aq)
[Fe(H... show full transcript
Worked Solution & Example Answer:Figure 3 shows some reactions of aqueous iron ions - AQA - A-Level Chemistry - Question 4 - 2019 - Paper 1
Step 1
Give the formula of Precipitate J and state its colour. Give an equation for Reaction 1.
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Answer
Formula of J: The formula for Precipitate J is Fe(OH)3.
Colour: The precipitate is typically brown.
Equation: The equation for Reaction 1 is:
ightarrow 2Fe(OH)_3 + 3Na^+$$
Step 2
Give the formula of L and an equation for Reaction 2.
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Answer
Formula of L: The formula for Complex ion L is [Fe(H2O)6]3+.
Equation: The equation for Reaction 2 is:
ightarrow [FeCl_6]^{3-} + 6H_2O$$
Step 3
Suggest a reagent for Reaction 3.
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A suitable reagent for Reaction 3 is concentrated hydrochloric acid (HCl) or potassium iodide.
Step 4
Give the formula of Precipitate M and state its colour.
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Answer
Formula of M: The formula for Precipitate M is Fe(OH)2.
Colour: The precipitate is generally green.
Step 5
Describe the different shapes of complexes and show how they lead to different types of isomerism.
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Shapes of Complexes:
Octahedral: The most common shape, involving six ligands surrounding a central metal ion. Examples include [Co(NH3)6]3+.
Tetrahedral: Four ligands arranged around a central metal ion. Examples include [CuCl4]2−. This shape typically leads to geometric isomerism.
Square Planar: Common with d8 metal ions, using four ligands in a square arrangement. An example is [PtCl4]2−.
Isomerism:
Geometric Isomerism: Occurs in square planar and octahedral complexes. For instance, in [Co(NH3)4Cl2]+, we can have cis and trans forms.
Optical Isomerism: This occurs in octahedral complexes where structures are non-superimposable mirror images, such as in [Co(en)3]3+, where 'en' stands for ethylenediamine.
Diagrams: Draw structures for the complexes, including those showing different isomeric forms.
