Metal Aqua Ions Flashcards
Explain why metal 3+ ions are more acidic than 2+ ions? [3]
(3+) ions are smaller / have higher charge density 1
are more polarising / attract electrons from oxygen more strongly 1
weakens O-H bond so more H+ is released / dissociated 1
State the formula of the the complex ion formed when Fe [3+] is dissolved in water, and deduce the shape and colour of the ion? [3]
[Fe(H2O)6] [3+] 1
(Octahedral )ONLY 1
brown / yellow (solution) 1
When small amounts of sodium hydroxide are added to [Cu(H20)6] [2+]
a metal hydroxide forms
State the formula of the complex formed and the colour of the ion?[2]
Explain why the reaction produces an insoluble solid?[2]
[Cu(H2O)4(OH)2] 1
Blue(gelatinous) ppt 1
hydroxide is neutral overall / has no charge 1
ion is not attracted to water molecules 1
What will happen to the position of the equilibrium when OH- is added to a metal aqua ion and explain why? [2]
Shifts to the right 1
H3O + / H+ ions are removed to form H2O 1
Aluminium hydroxide is described as being amphoteric
State the meaning of the term amphoteric? [1]
Deduce the formula of the complex formed when excess NaOH is added to aluminium hydroxide and explain why this happens? [2]
Can act as a acid or a base 1
[Al(OH)4]- / accept H2O in formula 1
it donates H+ / acts a Brønsted Lowry acid 1
A student added HCl to copper(II)hydroxide
Deduce the formula of the complex formed, and explain why it does this? [3]
[Cu(H2O)6] [2+] 1
Acts a Brønsted Lowry base 1
Accept H+ ions 1
Deduce the formula of the complex formed when small amounts of NH3 is added to a Fe(III)aqua ion? [1]
Explain why this occurs with the aid of an equation? [2]
[Fe(H2O)3(OH)3] 1
produces OH- ions / acts a base 1
NH3 + H3O+ ——> NH4 + + OH- 1
Write an equation for the reaction of copper(II) ions with an excess of NH3
Deduce a name for this type of reaction and suggest why the precipitate will dissolve? [3]
Cu(H2O)4(OH)2 + 4NH3 ———> [Cu(H2O)2(NH)4] [2+] + 2OH- + 2H2O 1
ligand substitution 1 it is (charged) so is soluble 1
Both copper(II) ions and cobalt(II) ions undergo ligand substitution with excess of NH3 Deduce a formula for the complexes formed and the colour changes that would be observed? [2]
[Cu(H2O)2(NH3)4] [2+]
blue ppt —> deep blue solution Both for 1 mark
[Co(NH3)6] [2+]
blue ppt —> pale yellow solution Both for 1 mark
State what would happen to the cobalt ions when exposed to oxygen, and the colour observed? [2]
Co(II) would be (oxidised) to form Co(III) 1
form a brown solution 1
Deduce an equation for the reaction that occurs when HCl is added to an aqueous solution containing Cu (II)
and identity the shape and colour of the complex ion formed? [3]
[Cu(H2O)6] [2+] + 4Cl- ——-> [Cu(Cl)4] [2-] + 6H2O
tetrahedral 1
yellow 1
Explain why the shape of [Cu(Cl)4] [2-] is different from that of [Cu(H20)6] [2+]? [2]
(Cl-) is a larger ligand than water 1
fewer ligands can fit around central metal ion 1
Write an equation for the reaction of Na2CO3 with a solution containing Fe( II ) ions? [1]
Identity would colour would be observed? [1]
[Fe(H2O)6] [2+] + CO3 [2-] —–> FeCO3 + 6H2O 1
green ppt 1
When Na2CO3 was added to a solution of Fe ( III ) ions bubbles were given off
Explain why this observation was made, and deduce the identity of the bubbles given off? [4]
(3+ ions) are more acidic so dissociate more H+
OR release more H3O+ into solution 1
CO3 [2-] reacts with H3O+ / removes H3O+ 1
equilibrium shifts to the right 1
CO2 (ONLY) 1
When CuCl is dissolved in an excess of hydrochloric acid, a colourless solution containing the complex ion, [CuCl2]–, is formed. When H2O2 is added to this acidified solution, a green solution containing a copper complex ion, X, and water are formed. On the addition of excess water, a blue solution containing the copper complex ion, Y is formed.
Give the formula and shape of the copper complex ion X? [2]
State the role of hydrogen peroxide in the formation of X? [1]
Write an equation for the formation of Y from X and identify the role of water in this reaction? [2]
(X) [CuCl4] [2-] 1
tetrahedral 1
oxidising agent 1
[CuCl4] [2-] + 6H2O —–> [Cu(H2O)6] [2+] + 4Cl– 1
Ligand OR electron pair donor 1
