Transition metals tests for practical assessments edexcel A2

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Transition metals

They all form coloured ions and have multiple oxidation states which means that many of them are able to catalyse reactions , one example is the haber process from making ammonia where an Iron catayst is used. They all form complexed ions and this often occurs by ligand exchange after deprotonation.

A transition metal has one or more unpaired electrons in at least one of its stable ions. D block elements have their outer shell electrons in  a D orbital. ( you always lose the 4s electrons first )

Cu and Cr do not follow the pattern  Ar 3d5 4s1 is Cr and 3d10 4s1 is Cu.The way of working out the rest is a full 4s orbital so 4s2 and then from Sc with 1 3d electron , add a 3d electron.

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Reactions of Fe+3

With NaOH

you form a gelatenous brick/brownprecipitate, in excess NaOH you get no change

With NH3

you form a thick gelatenous brown  precipitate In excess NH3 no change

If you add NaCO3 to this mixture you get fizzing and a brown precipitate, and by adding HCl to this you get a dark green precipitate and fizzing bubbles

The ion in solution is a brick red colour like rust

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Reactions of Fe+2

In solution you form a pale green colour

With NaOH

You form  a dark green precipitate with darkened edges.With excess NaOH there is no change

With NH3

You form A green brown Precipitate which like the above after standing forms darkened egdes. With excess NH3 there is no change

It forms a dark green precipitate with NaCO3 but does not fizz like an acid would, when H2O2 hydrogen peroxide is added to this mixture you form a pale yellow coloured precipitate

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Reactions of Mn+2

the ion in solution is colourless

With NaOH

forms a flesh toned precipitate, no change in excess , this combined with hydrogen peroxide forms

 With NH3

Fleshed toned precipitate forms , with excess NH3 you get no change

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Reactions of Ni+2

The aqueous ion is a pale green

With NaOH

you get a pale green prcipitate with no change on addition of excess

With NH3

plae green precipitate which turns to  a blue solution in excess NH3

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Reactions of Cr+3

In solution it is a dark green colour

With NH3

Milky green precipitate which goes violet on standing with excess NH3

With NaOH

Dark Green precipitate, in excess there is a dark green solution formed

With NaOH in excess and H2O2

you get fizzing to form an olive coloured PPT which turns yellow on heating

FeSO4 can be oxidised with K2Cr2O7 and H2SO4 to form a yellow brown precipitate

The Cr(OH)3 is amphoteric

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Reactions of Cu+ and Cu+2

with Fehlings solution this forms a red brown precipitate like an aldehyde would this is because the solution acts as a reducing agent

CuSO4 ( yes Cu+2 i know) with KI and Sodiumthiosulphate will form a pinky cream precipitate.

Cu+2 in solutuion is a dark bright blue

With NaOH you form a blue gelatenous precipitate

With Ammonia you form a dark blue solutuion which will have a pale blue precipitate as the bottem of the test tube if you add conc HCl and water to this you form a pale green colour solution

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Reactions of Zn +2

remember that Zinc is not strictly a transition metal because ti does not have an unpaired electron in its outer shell of a stable ion ( in the case of the Zn+2 you have an electron arrangement of Ar 3d10)

in solution it forms a clear colourless solution

With NaOH it forms a white gelatenous precipitate which dissolves in excess

With NH3 you also get a white gelatenous Precipitate but it will go powdery and dissolve in excess NH3

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