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) → ... 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.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The formula for Precipitate J is [ Fe(OH)_{3} ]. Its colour is brown.
The equation for Reaction 1 is:
2Fe3++3CO32−→2Fe(OH)3+3H2O
Step 2
Give the formula of L and an equation for Reaction 2.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The formula for Complex ion L is [ [Fe(H_2O)_{6}]^{3+} ].
The equation for Reaction 2 is:
[Fe(H2O)6]3++6HCl→[FeCl6]3−+6H2O
Step 3
Suggest a reagent for Reaction 3.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
A suitable reagent for Reaction 3 is potassium iodide, [ KI ].
Step 4
Give the formula of Precipitate M and state its colour.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The formula for Precipitate M is [ Fe(OH)_{2} ]. Its colour is generally green.
Step 5
Describe the different shapes of complexes and show how they lead to different types of isomerism. Use examples of complexes of cobalt(II) and platinum(II).
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Transition metal complexes can adopt various geometries, primarily octahedral and tetrahedral shapes:
1. Octahedral Complexes:
Example: [ [Co(NH_3)_6]^{3+} ] has an octahedral shape.
Isomerism Type: Geometric isomerism can occur in complexes having different arrangements of ligands (cis and trans).
Structure:
2. Tetrahedral Complexes:
Example: [ [CoCl_4]^{2-} ] shows a tetrahedral shape.
Isomerism Type: Ligand exchange between different positions leads to structural isomerism.
Structure:
3. Square Planar Complexes:
Example: [ [PtCl_4]^{2-} ] has a square planar geometry.
Isomerism Type: This shape exhibits cis-trans isomerism with different arrangements of ligands.
Structure:
Each complex shape not only influences the properties of the complexes but also their reactivity and interaction with light, leading to the different colors seen in transition metal compounds.
