A Level Inorganic Chemistry Flashcards

Question

What shape are 4 coordinate bonds and what’s their bond is their bond angles?

Answer 1

Tetrahedral shape Bond angle = 109.5 degrees E.g: [CuCl4]2- = yellow [CoCl4]2- = blue Square planar Bond angle = 90 degrees E.g: Cisplatin

Answer 2

Linear shape Bond angle = 180 degrees E.g: [Ag(NH3)2]+ AKA Tollens reagent

Answer 3

Oxidation state of the metal ion = total oxidation state - the sum of the oxidation states of the ligands

Answer 4

Mono-dentate ligands = can only form one coordinate bonds e.g. NH3, Cl-, CN-, OH-, H2O Multi-dentate ligands = more than one coordinate bond e.g. EDTA4- binds to metal ions and is known as a chelating agent Bidentate ligands = can only form two co-ordinate bonds e.g. 1,2-diaminoethane, NH2CH2CH2NH2, ethandioate

Answer 5

Haemoglobin is a protein found in blood that helps to transport oxygen around the body It contains Fe2+ ions, which are hexa-coordinated - six lone pairs are donated to them to form six co-ordinate bonds in an octahedral structure Four of the co-ordinate bonds come from a single multi-dentate ligand, four nitrogen atoms from the same molecule co-ordinate around Fe2+ to form a circle, this is the haem The other two co-ordinate bonds come from the protien, globin and either an oxygen or a water molecule - so the complex can transport oxygen to where it’s needed.

Answer 6

- in the lungs, where the oxygen concentration is high, an oxygen molecule substitutes the water ligands and bonds coordinately to the Fe(II) ion to form oxyhaemoglobin, which is carried around the body in the blood - when the oxyhaemoglobin gets to a place where oxygen is needed, the oxygen molecule is exchanged for a water molecule, and the haemoglobin returns to the lungs etc

Answer 7

The haemoglobin swaps the water ligands for a carbon monoxide ligand, forming carboxyhaemoglobin, the carbon monoxide is a very strong ligand and doesn’t readily exchange with oxygen or water, meaning the haemoglobin can’t transport oxygen any more Carbon monoxide poisioing starves the organs of oxygen - it causes headaches, dizziness, unconsciousness and death if not treated

Answer 8

Optical isomerism is a type or stereoisomerism - complex ions can show optical isomerism - where an ion can exist in two forms that’s are non-superimposable mirror images - this happens with octahedral complexes when three bidentate ligands, coodinatley bond with a central metal ion

Answer 9

Octahedral complexes with four monodentate ligands of one type and two monodentate ligands of another type can show cis-tans isomerism, if the two odd ligands are opposite each other, you have got a trans isomer, if they are next to each other it is the cis isomer Square planar complexes ions that have two pairs of ligands also show cis-trans isomerism, when two paired ligands are opposite each other its the trans isomerism and when they are next to each other its is the cis isomer

Answer 10

Usually = 3d orbitals ion all have the same energy With ligands = some of the orbitals gain energy Which splits the energy levels into two different levels - electrons tend to occupy the lower orbital, to jump to the higher levels they need energy equal to the energy gap, which they get form visible light

Answer 11

Planck’s constant (J s) x the speed of light (3.00x10power of 8 m s-1) DeltaE = Planck’s constant x frequency of light absorbed(Hz) = ———————————————————- Wavelength of light absorbed (m) Planck’s constant = 6.63 x10 power of -34

Answer 12

The colours of the compound are the complement of the colours absorbed - some frequencies are absorbed when electrons jump up to the higher orbitals, the rest a tansmitted or reflected, which combine to make the complement of the colours absorbed which is the colour you can see

Answer 13

- white light is shone through a filter, which is chosen to only let through the colour of the light that is absorbed by the sample - the light passes through the sample to a colorimeter, which calculates how much light was absorbed - the more concentrated a coloured solution is, the more light it will absorb, so you can use this measurement to work out the concentration of a solution of transition metal ions

Answer 14

[Cu(H2O)6]2+(aq) + 4NH3(aq) —> [Cu(NH3)4(H2O)2]2+(aq) + 4H2O(l) Light blue solution. Deep blue solution [Cu(H2O)6]2+(aq) + 4Cl-(aq) —> [CuCl4]2-(aq) + 6H2O(l) Light blue solution. Yellow solution

Answer 15

[Co(H2O)6]2+(aq) + 6NH3(aq) —> [Co(NH3)6]2+(aq) + 6H2O(l) Pink Orange [Co(H2O)6]2+(aq) + 4Cl-(aq) —> [CoCl4]2-(aq) + 6H2O(l) Pink. Blue

Answer 16

[Fe(H2O)6]3+(aq) + 4Cl-(aq) —> [FeCl4]-(aq) + 6H2O(l)

Answer 17

[Cu(H2O)6]2+(aq) + 3NH2CH2CH2NH2(aq) —> [Cu(NH2CH2CH2NH2)3]2+(aq) + 6H2O(l)

Answer 18

Is the extra stability of complexes with bidentate or multidentate ligands due to the entropically favoured reaction forming more moles The bonds broken and formed are largely the same and so similar strength, therefore deltaH is likely to be close to 0, so deltaS is the important factor regardless of T AG = AH - TAS

Answer 19

Like and exchange reactions occur when coordinate bonds are broken and formed - The strength of the bonds being broken is often very similar to the strength of the bonds being made, so the entropy change for a ligand exchange reaction is usually very small This is clear through an example: - The reaction substituting ammonia with ethane-1,2-diamine in a nickel complex has a very small entropy change - It is a reversible reaction but the equilibrium lies so far to the right where it is much more stable - When the hexadentate ligand EDTA4+ replace a monodentate or bidentate ligands the complex is much more stable

Answer 20

V02 + aq) yellow

Answer 21

VO 2+ blue

Answer 22

V 3+ (aq) green

Answer 23

V 2+ (aq) violet

Answer 24

Yellow —> blue 2VO2 +(aq) + Zn(s) + 4H+ —> 2VO 2+(aq) + Zn 2+(aq) + 2H2O(l) Blue —> green 2VO 2+(aq) + Zn(s) + 4H+ —> 2V 3+(aq) + Zn 2+(aq) + 2H2O(l) Green —> violet 2V 3+(aq) + Zn(s) —> 2V 2+(aq) + Zn 2+(aq)

Answer 25

The redox potential of an ion or atom tells you how easily it is reduced to a lower oxidation state The larger the redox potential the less stable the iron will be and so the more likely it is to be reduced

Answer 26

Within a ligand = standard electrode potentials are measured in aqueous solutions to any aqueous irons will be surrounded by water ligands, different ligands may make the redux potential larger or smaller depending on how well they buy into the metal ion in a particular oxidation state Ph = some ions need H plus ions to be present in order to be reduced others release OH minus ions when they are reduced, for reactions like these the pH of the solution affects the size of the redox potential but in general redox potential will be larger and more acidic solutions making the ion what easily reduced

Answer 27

Ag+(aq) + e- —> Ag SEP = +0.80V

Answer 28

When added to aledehydes Tollen reagent reacted to give a silver mirror, the aldehyde is oxidised to a carboxylic acid and the Ag+ ions are reduced to silver metal When added to ketones, they can’t be oxidised by tollens reagent so it won’t react with them and no silver mirror form

Answer 29

Transition metals and their compounds make good catalyst because they can change oxidation states by gaining or losing electrons within the d orbitals, this means they can transfer electrons to speed up reactions for example, the contact process uses vanadium(V) oxide which oxidises sulphur dioxide to sulphur trioxide because it can be reduced to vanadium(IV) oxide, it is then oxidised back to vanadium(V) oxide by oxygen ready to start again

Answer 30

Heterogeneous catalysts are one are in a different phase from the reactants The reaction happens on the active sites located on the surface of the heterogeneous catalyst, so increasing the surface area of the catalyst increases the number of molecules that can react at the same time therefore increasing the rate of reaction - Support mediums are often used to make the area of the catalyst as large as possible and they help to minimise the cost because only a small coating of catalyst is needed to provide a large surface area E.G. Iron in the Haber process. E.G. Vanadium(V) in the contact process

Answer 31

Heterogeneous catalysts work by absorbing reactants onto active sites located on their surface impurities in the reaction mixture may also buy into the catalyst surface and block the reactant active sites, this is catalytic poisoning - Reduces the surface area - Increases the cost because less product can be made and the catalyst may need replacing or regenerating - E.G.sulphur poisons the iron in the Haber process

Answer 32

Homogeneous catalysts are in the same physical phase as the reactant They work by combining with the reactants to form an intermediate species which then reacts to form the products and reform the catalyst The enthalpy profile for a homogeneously catalysed reaction has two humps in it corresponding for the two steps in the reaction The activation energy needed to form the intermediate is lower than that to make the products directly

Answer 33

The redox reaction between iodide ions and peroxodisulfate ions takes place annoyingly slowly because both ions are negatively charged the islands repel each other so it is unlikely that they will collide and react S2O8 2-(aq) + 2I-(aq) —I2(aq) + 2SO4 2-(aq) But if Fe2+ ions are added, it speed it up because each stage of the reaction involves a positive and negative ion S2O8 2-(aq) + 2Fe2+(aq) —> 2Fe3+(aq) + 2SO4 2-(aq) 2Fe3+(aq) + 2I-(aq) —> I2(aq) + 2Fe2+(aq)

Answer 34

Is when a product catalyses the reaction - Mn2+ is an auto catalyst as it is the product of the reaction and act as a catalyst which means that the reaction progresses and the amount of the product increases and the reaction speeds up 2MnO4 -(aq) + 16H+(aq) + 5C2O4 2-(aq) —> 2Mn2+(aq) + 8H2O(l) + 10CO2 (g) MnO4 -(aq) + 4Mn2+(aq) + 8H+(aq) —> 5Mn3+(aq) + plus4H2O(l) 2Mn3+(aq) + C2O4 2-(aq) —> 2Mn 2+(aq) + 2CO2(g)

Answer 35

Transition metal compounds dissolve in water, the water molecules form co-ordinate bonds with the metal ions This forms metal-aqua complex ions, six water molecules coordinatley bonded with each metal ion - water molecules donated a non-bonding pair of electrons from their oxygen E.g. [Fe(H2O)6]2+ and [Al(H2O)6]3+

Answer 36

In a solution containing metal aqua 2+ ions there’s a reaction between the metal-aqua ion and the water - a hydrolysis reaction - the metal-aqua 2+ ions release H+ ions, so an acidic solution is formed, there is only slight dissociation through so the solution is only weakly acidic - metal-aqua 3+ ions dissociate more and so form more acidic solutions

Answer 37

Metal 3+ ions are small but have a big charge = high changer density This makes the 3+ ions much more polarising than the 2+ ions, more polarising power means that they attract electrons from the oxygen atoms of the coordinated water molecules more strongly, weakening the O-H bond - so it is more likely that a hydrogen ion will be released, and more hydrogen ions means a more acidic solution

Answer 38

In water, metal-aqua 3+ ions such as Fe3+ and Al3+ form an equilibrium, if you add OH- ions to the equilibrium, H3O+ ions are removed and the equilibrium shifts to the right: 3+ +H2O <=> 2+ + H3O+ Another equilibrium was set up: 2+ + H2O <=> + + H3O+ Again the OH- ions remove the H3O+ from the solution pulling the equilibrium right One last time and you are now left with an insoluble, uncharged metal hydroxide + + H2O <=> Solid + H3O+

Answer 39

All metal hydroxide precipitates with dissolve in acids, where they act as bronsted lowery bases and accept H+ ions, which reverses the hydrolysis reaction Some are amphoteric and will dissolve in an excess of base as well as in acids Aluminium hydroxide is amphoteric

Answer 40

NH3(aq) + H2O(l) <=> NH4+(aq) + OH-(aq) Because hydroxide ions are formed, adding a small amount of ammonia solution gives the same results as sodium hydroxide In some cases like Cu(OH)2(H2O)4 a further reaction happens if you add excess ammonia solution, the H2O and OH- ligands are displaced by NH3 ligands, forming a charged complex which is soluble in water so the precipitate dissolves

Answer 41

Metal 2+ ions react with sodium carbonate to form insoluble metal carbonates But metal 3+ ions are stronger acids so there is a higher concentration of H3O+ ions in solutions, rather then displacing eater from the metal ions, the carbonate ions react with H3O+, removing them from the solution and shifting the equilibrium of the reactant to the right

Answer 42

All four metal aqua ions will form precipitates with sodium hydroxide, but only ALUMINIUM HYDROXIDE will dissolve in an excess of sodium hydroxide as it is amphoteric

Answer 43

All for metal aqua ions will form precipitates with ammonia, but only the COPPER HYDROXIDE will dissolve in an excess of ammonia, as it undergoes a ligand exchange reaction with excess ammonia solution

Answer 44

All four metal aqua ions will form precipitates with sodium carbonate, solutions containing Al3+ or Fe3+ will also form bubbles as CO2 is formed, but Fe2+ will not form bubbles

Answer 45

[Cu(H2O)6] 2+ blue solution Cu(OH)2(H2O)4 blue precipitate NO CHANGE [Cu(NH3)4(H2O)2] 2+ deep blue solution CuCO3 green-blue precipitate

Answer 46

[Fe(H2O)6] 2+ green solution Fe(OH)2(H2O)4 green precipitate NO CHANGE NO CHANGE FeCO3 green precipitate

Answer 47

[Al(H2O)6] 3+ colourless solution Al(OH)3(H2O)3 white precipitate [Al(OH)4]- colourless solution NO CHANGE Al(OH)3(H2O)3 white precipitate

Answer 48

[Fe(H2O)6] 3+ yellow sol Fe(OH)3(H2O)3 brown ppt NO CHANGE NO CHANGE Fe(OH)3(H2O)3 brown ppt

A Level Inorganic Chemistry Flashcards

(72 cards)