Which of the following is true about the bonding in metal-aqua ions?
Water molecules act as Brønsted-Lowry acids
Metal ions act as Brønsted-Lowry bases
Water molecules act as Lewis bases
Metal ions act as proton acceptors
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Which of the following is true about the bonding in metal-aqua ions?
Water molecules act as Brønsted-Lowry acids
Metal ions act as Brønsted-Lowry bases
Water molecules act as Lewis bases
Metal ions act as proton acceptors
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Which of the following is true about metal-aqua ions?
All aqueous transition metal ions are neutral
Transition metal ions with a +2 charge are acidic
Deprotonation occurs in all transition metal ions
Transition metal ions with a +3 charge are acidic
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A white precipitate with some bubbles could be the observations in which of the following reactions?
CuCl2 + NH3
Al2(SO4)3 + Na2CO3
H2SO4 + Na2CO3
BaCl2 + Na2SO4
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Aqueous iron(II) ions react with ammonia according to the following equation:
[Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)
In this reaction, what is the role of the ammonia?
|
Base |
Nucleophile |
Ligand |
A |
✓ |
✓ |
✓ |
B |
✓ |
✓ |
⨯ |
C |
⨯ |
✓ |
✓ |
D |
✓ |
⨯ |
⨯ |
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Copper(II) nitrate can undergo the following sequence of reactions:
The reagents needed to carry out steps 1, 2 and 3 could be
|
Step 1 |
Step 2 |
Step 3 |
A |
Excess H2O |
Drops of NaOH (aq) |
Drops of conc. HCl (aq) |
B |
Excess H2O |
Excess NH3 (aq) |
Drops of conc. HCl (aq) |
C |
Excess H2O |
Drops of NH3 (aq) |
Excess NH3 (aq) |
D |
Excess H2O |
Drops of NH3 (aq) |
Excess H2O |
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Iron(III) forms a complex ion [Fe(H2O)6]3+.
What is the role of the water molecule in this species?
Brønsted-Lowry acid and Lewis base
Brønsted-Lowry base and Lewis base
Brønsted-Lowry base only
Lewis base only
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Transition metal ions with the general formula, M3+, will often undergo hydrolysis reactions in water. One such ion is Fe(III) and the reactant side of the hydrolysis equation is:
[Fe(H2O)6]3+ + H2O ⇌ ------------------- + -------------------
Which of the following correctly completes the equation?
[Fe(H2O)5(OH)]2+ + H+
[Fe(H2O)5(OH)]3+ + H3O+
[Fe(H2O)5(OH)]2+ + H3O+
Fe(H2O)3(OH)3 + 3H+
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Which of the following ions produces identical observations when sodium hydroxide or ammonia solutions are added until in excess?
[Fe(H2O)6]2+
[Al(H2O)6]3+
[Cu(H2O)6]2+
[Co(H2O)6]2+
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Chelation is the formation of complexes with multidentate ligands.
Which of the following is true about chelation?
Stronger bonds are formed between the multidentate ligands and the central metal ions
The chelated complexes are more stable due to positive entropy changes
The number of entities decreases in chelation which favours the reaction
Negative enthalpy changes during chelation favour the reactions
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Aqueous iron(III) ions react with sodium carbonate solution.
What happens in the reaction?
|
Observations |
Products |
||
A |
Brown precipitate |
Bubbles of gas |
Fe(H2O)3(OH)3 |
CO2 |
B |
Brown precipitate |
- |
Fe2(CO3)3 |
- |
C |
Orange solution |
- |
[Fe(H2O)5(OH)]2+ |
- |
D |
Brown precipitate |
Bubbles of gas |
Fe2(CO3)3 |
CO2 |
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Two possible reactions of hydrated chromium(III) hydroxide are shown below.
Which statement about these reactions is correct?
Reaction 1 shows the hydrated chromium(III) hydroxide acting as a Brønsted–Lowry acid
Reactions 1 and 2 are examples of ligand substitution reactions
Reactions 1 and 2 display the amphoteric nature of hydrated chromium(III) hydroxide
Reaction 2 shows the hydrated chromium(III) hydroxide behaving as a Brønsted–Lowry base
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Hexa-aqua solutions of transition metals in the +2 oxidation state, [M(H2O)6]2+ (aq), can react with excess aqueous ammonia to form various complexes.
Which of the following statements about these reactions with excess aqueous ammonia is correct?
[M(H2O)6]2+ (aq) can form products that exist as stereoisomers
[M(H2O)6]2+ (aq) undergo full ligand substitution to form [M(NH3)6]2+ (aq)
[M(H2O)6]2+ (aq) forms products with the transition metal in the +3 oxidation state
[M(H2O)6]2+ (aq) can form precipitates of [M(H2O)4(NH3)2] (s)
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The reactions of three different metal complexes with aqueous sodium hydroxide are shown in the table.
Formula of complex ion |
Addition of small amount of NaOH (aq) |
Addition of excess NaOH (aq) |
[M(H2O)6]2+ |
Coloured precipitate forms |
No further change |
[X(H2O)6]3+ |
Coloured precipitate forms |
Precipitate dissolves |
[Q(H2O)6]3+ |
White precipitate forms |
Precipitate dissolves |
Which statement about the metals is most likely to be true?
Q is not a transition metal
The [M(H2O)6]2+ complex will react with carbonate ions to produce carbon dioxide
[X(H2O)6]3+ forms a precipitate with carbonate ions with the formula XCO3
[Q(H2O)6]3+ forms a coloured solution when excess aqueous ammonia is added
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The pH of a 1.0 mol dm-3 solution of aluminium chloride is approximately 3, whereas the pH of a 1.0 mol dm-3 solution of iron(II) chloride is approximately 5.
What is the best explanation for this?
The Al3+ has a greater charge density than the Fe2+ ion
The aluminium chloride solution contains more ions
The Al3+ ion has a greater nuclear charge than the Fe2+ ion
The aqueous Al3+ ion has a greater coordination number than the Fe2+ ion
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Which of the options below shows the correct observation and chemical explanation for the reactions of a solution of iron(II) chloride?
|
Substance added (in excess) |
Observation |
Explanation |
A |
Na2CO3 (aq) |
Green precipitate which redissolves to form a green solution |
Carbonate ions act as a base, removing H+ from the water molecules in the complex |
B |
NH3 (aq) |
Green precipitate which redissolves to form a green solution |
A ligand exchange reaction occurs - ammonia displaces |
C |
Na2CO3 (aq) |
Green precipitate which does not redissolve; fizzing |
Carbonate ions act as a base, removing H+ from the water molecules in the complex. CO2 gas is also formed. |
D |
NH3 (aq) |
Green precipitate which does not redissolve |
Ammonia acts as a base, removing H+ from the water molecules in the complex |
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