Inorganic Reactions Flashcards
How many water molecules are able to bond to one transition metal?
Six!
What is a Lewis Base?
An electron acceptor.
Gie an example of a Lewis acid-base reaction.
NH3(aq) + BF3(aq)—-> NH3BF3(aq)
What do Lewis acids and bases react to form?
Coordinate bonds.
Why is it that solutions containing metal-aqua ions are slightly acidic?
Because aqua-metal ions react with the water to form H3O+ ions - the metal-aqua ions behave as a weak acid.
Why is it that solutions containing metal-aqua 3+ ions are more acidic than solutions containing metal-aqua 2+ ions?
3+ ions have a high charge density than 2+ ions - they polarize the oxygen in the water more strongly. This weakens the OH bond in water, making it easier for it to release a proton.
Give the dissociation reaction of [Al(H2O)6]3+ in water.
[Al(H2O)6]3+ + H2O —-> [Al(H2O)5(OH)]2+ + H3O+
Give the overal hydrolysis reaction of [M(H2O)6]3+ to its precipitate.
[M(H2O)6]3+(aq) + 3H2O(l) —-> M(H2O)3(OH)3(s) + 3H3O+(aq)
How can a metal hydroxide be dissolved?
By the addition of the acid - this will turn the hydroxide into the highest oxidation state of the metal-aqua ion.
Which metal hydroxides dissolve in bases? Why and how do they do this?
Al(H2O)3(OH)3 and Cr(H2O)3(OH)3 are amphoteric and are able to react with a base by donating a proton to form a negative ion and water.
i.e. Al(H2O)3(OH)3(s)+ OH-(aq) —-> [Al(H2O)2(OH)4]-(aq) + H2O(l)
Why is it that adding ammonia to a solution makes it basic?
The ammonia reacts with the water to form ammonium and hydroxide ions.
How is it possible to form a non-soluble precipitate from a metal-aqua 2+ ion? Give an example reaction with [M(H2O)6]2+
By reacting a carbonate (i.e. Na2CO3)
[M(H2O)6]2+(aq) + CO32-(aq) <—-> MCO3(s) + 6H2O(l)
How is it possible to form a precipitate from a metal-aqua 3+ ion? What occurs in the reaction process for this that prevents the precipitate dissociating in acid?
By reacting the 3+ ions with a carbonate - the carbonate ions react with the H3O+, removing them from the solution and keeping the pH neutral.
What is the reaction between Cu (II) metal-aqua ions and NH3?
NH3 + H2O <—-> OH- + NH4+
[Cu(H2O)6]2+ + 2OH- —-> Cu(H2O)4(OH) + 2H2O
What is the reaction between Cr (III) metal-aqua ions and excess hydroxide ions?
[Cr(H2O)6]3++ 6OH-—-> [Cr(OH)6]3- + 6H2O
What happens to cobalt, copper and chromium metal-aqua ions when they are reacted with excess NH3?
The NH3 replaces the water ligands; all of them, apart from copper, which only gains 4 and keeps 2 H2O ligands.
What is the reaction between Aluminium aqua-metal ions and excess OH-?
[Al(H2O)6]3+ + 4OH- —-> [Al(H2O)2(OH)4]- + 4H2O
What is the reaction between Fe (III) and excess hydroxide ions?
The same as without excessive hydroxide ions - Fe (III) does not behave amphoterically.
[Fe(H2O)6]3+ + 3OH- —-> Fe(H2O)3(OH)3 + 3H2O
What is the reaction between cobalt (II) metal-aqua ions and Na2CO3?
[Co(H2O)6]2+ + CO32- —-> CoCO3 + 6H2O
What is the reaction between Cr (III) metal-aqua ions and Na2CO3?
[Cr(H2O)6]3+(aq) + 3H2O(l) —-> Cr(H2O)3(OH)3(s)
The carbonate removes the H3O+ ions formed.
CO32- + H+ —-> HCO3-
HCO3- + H+ —-> H2O + CO2