1
Q
what are d block elements
A
- across the periodic table from scandium to zinxc
- 3d sub shell has the highest energy and electrons are added to 3d orbitals
2
Q
what are properties of d block elements
A
- metallic
- display the typical physical properties of metals
- high melting and boiling points
- shiny in appearance
- conduct both electricity and heat
3
Q
what are copper, silve , nickel and zinc used in
A
coinage
4
Q
what are the uses of iron
A
- construction
- production of tools
5
Q
what are the uses of copper
A
- electrical cables
- water pipes
6
Q
what are the functions of titanium and why
A
- known for it great strength
- used in aerospace industry as well as medical applications such as join replacement
- cosmetic dentistry
7
Q
what is the electron configuation of chromium
A
1s2 2s2 2p6 3s2 3p6 3d5 4s1
8
Q
what is the electron configuation of copper
A
1s2 2s2 2p6 3s2 3p6 3d10 4s1
9
Q
why are chromium and copper do not have the expected principle of placing electrons singly in orbitals before pairing
A
- stability
- half filled d5 sub shell and fully filled d10 sub shell give additional stability to atoms of chomium and copper
10
Q
describe how d block element for positive ons from their atoms
A
- lose their 4s electrons before losing there 3d electrons
- when forming an atom the 4s orbital fills before the 3d orbitals
- when forming an ion the 4s orbital empties before the 3d orbitals
11
Q
what is the definition of a transition element
A
defined as d block elements that form at least one ion with a partially filled d orbital
12
Q
why are scandium and zinc not classified as transition elements
A
- Sc3+ ions have empty d orbitals
- Zn2+ ions have full d orbitals
- so scandium and zinc do not form ions with partially filled d orbitals and are not therfore classfied as transition elements
13
Q
what are the characteristic properties of transition elements that make them different from other metals
A
- they form compounds in which the transition element has different oxidation states
- they form coloured compounds
- element and their compounds can act as catalysts
14
Q
describe the trend in oixidation states through transition elements
A
- the number of oxidation states increases across the transition elements series to managneses and then decreases
- all of the transition elements form compounds with an oxidation number of +2 resulting from the loss of two electrons
- each oxidation state often has a characteristic colour
15
Q
what are the oxidation states formed from Sc and what are the respective colour compounds formed
A
- +3 - white
16
Q
what are the oxidation states formed from Ti and what are the respective colour compounds formed
A
- +2 - white
- +3 - lilac
- +4- white
- +5- white
17
Q
what are the oxidation states formed from V and what are the respective colour compounds formed
A
- +2 - lilac
- +3 - green
- +4 - blue
- +5 - yellow
18
Q
what are the oxidation states formed from Cr and what are the respective colour compounds formed
A
- +2- blue
- +3 - green
- +4 - white
- +5 - white
- +6 - orange
19
Q
what are the oxidation states formed from Mn and what are the respective colour compounds formed
A
- +2 - light pink
- +3 - white
- +4 - maroon
- +5 - white
- +^- green
- +7 - lilac
20
Q
what are the oxidation states formed from Fe and what are the respective colour compounds formed
A
- +2 - light green
- +3 - cream
- +4 - white
- +5 - white
- +6 - white
21
Q
what are the oxidation states formed from Co and what are the respective colour compounds formed
A
- +2 - pink
- +3- green
- +4 - white
- +5 - white
22
Q
what are the oxidation states formed from Ni and what are the respective colour compounds formed
A
- +2 - green
- +3 - white
- +4 - white
23
Q
what are the oxidation states formed from Cu and what are the respective colour compounds formed
A
- +1 - white
- +2 - blue
- +3 - white
24
Q
what are the oxidation states formed from Zn and what are the respective colour compounds formed
A
- +2 - white
25
describe how oxidation state relates to oxidising agent
a species containing a transition element in its highest oxidation state is often a strong oxidising agent
26
what is the colour of potassium dichormate (VI)
bright orange
27
what i the colour of Cobalt (II) chloride
pink purple
28
what is the colour of nickel (II) sufate
green
29
what is the colour of hydrated coppe (II) sulfate
blue
30
how do transition elements produce coloured solution
solid compounds can be dissolved in water
31
what is the colour of the solution linked to
* partially filled d orbitals of the transition metal ion
* colour of solution can vary with differnet oxidation states
32
what are the two common oxidation states iron forms and it colour
* +2 - pale green
* +3 - yellow
33
what are the two common oxidation states formed from chromium
* +3 - green
* +6 - yellow or orange
34
what is a catalyst
* substance that increases the rate of a chemical reaction without itself changing
* works by providing an alternative reaction pathway with a lower activation energy
35
where are transition metals important catalysts
* industrial processes in the labrotary
36
haber process
* manufacture of ammonia from reaction between nitrogen and hydrogen
* catalysed by finely divided iron catalyst
* N2(g) + 3 H2 (g) -> 2NH3(g)
* reversible
37
contact process
* production of sulfur trioxide from the oxidation of suldur dioxide
* reaction catalysed by vanadium (v) oxide v2O5
* 2SO2(g) + O2(g) -> 2SO3 (g)
* reversible
38
hydrogenation of vegetable fats
* manufacture of margarine
* nickel as a catalyst
* C2H4 + H2 ->C2H6
39
catalytic decomposition of hydrogen peroxide
* form oxygen
* uses manganese (IV) oxide MnO2 (s) as the catalyst
* 2H2O2(aq) ->2H2O(l) + O2 (g)
40
what are hetergenous catalysts
as catalyst is a different state to the reactants
41
homogenous catalysts
catalyst same physical state as reactants
42
describe the reaction between idodie ions and peroxodisulffate ions S2O8 2-
* catalysed by fe 2+ wth reactans and catalsyt all in aqueous solution
* S2O82-9aq) +2I-(aq) -> 2So42-(aq) + I2 (aq)
* when reaction carried out with a trace of starch a blue black colour forms showing the formation off iodine
* if experiment is repeated with a small amount of Fe 2+(aq) added the blue black solution forms much more quickly demonstrating the catalytic action of the transition metal ion
* Fe 2+ (aq) reacts S2O82-(aq) + Fe2+ (aq) ->2So42-(aq) + Fe3+ (aq)
* Fe2+(aq) regenerated Fe3+ (aq) + 2I-(aq) ->I2 (aq) + Fe2+ (aq)
* so although Fe2+ is used up in the first step it is regenerated in the second step
* overall they are not consumer
43
what is zinc metal with acids catalysed by
* Cu2+ (aq) ions
* Zn(s) + H2SO4 9aq) -> ZnSO4 (aq) + H2 (g)
44
what is one of the most important properties of d block elements
to form complex ions
45
what complex ion is formed when solid hydrated copper (II) sulfate, CUSO4.5H2O is dissolved in water and the colour form
a blue solution forms containing the complex ion [Cu(H2O)6]2+
46
are complex ions restricted to d block elements
no other elements such as aluminium can form complex ions
47
what are ligands
* a complex ion is formed when one or more molecules or negativley charged ions bond to a central metal ion
* these molecules of ions are known as ligands
48
what is the definition of a ligand
defined as a molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond or dative covalent bond
49
what is a dative covalent bond or a coordinate bond
special kind of covalent bond formed when one of the bonded atoms proveds both of the electrons for the shared pair
50
what is the coordination number
indicates the number of coordinate bond attatched to the central metal ion
51
what is a ligand
* any molecule or ion that can donate a pair of electrons to a central metal ion
52
describe charges on a ligand
* some ligands like water are neutral and have no charge whereas other ligans like hydroxide ions are negativley charged
53
what is a monodentate ligand
* a ligand that is able to donate one pair of elecrons to a central metal ion
54
name some common ligands and the charge on the ligand
* water - H2O: -> neutral
* ammonia -:Nh3 -> neutral
* chloride :Cl- -> -1
* cyanide -:Cn- -> -1
* hydroxide - :OH- ->-1
55
what is a bidentate ligand
* some ligands can donate two lone pairs of electrons to the central metal ion forming two coordinate bonds
56
what are two most common bidentate ligands
* 1,2-diaminoethane
* ethanedioate (oxylate ion)
57
describe how 1,2-diaminoethane acts as a bidendate ligand
* each nitrogen atom donates a pair of electrons to the central metal ion forming a coordinate bond
58
how does ethandioate ion act as a bidendate ligand
* each negativley charged oxygen atom donates a lone pair of electrons to the central metal ion
59
give an example of a complex ion containing a bidendate ligand with cobalt and a 1,2 - diaminoethane ligand
* [Co(NH2CH2CH2NH2)3]3+
* oxidation number of Co is +3
* coordination number is 6 because there are three 1 ,2 - diamino ligands and each ligand forms two coordinate bonds
60
what are six coordinate complexes what shapes do they form
* many complex ions have a coordination number of six giving arize to an octahedral shape
61
give an example of a complex ion formed with a six coordinate complex from MnSO4
* when dissolved in water the complex [Mn(H2O)6]2+ is formed
* has an octahedral shape with bond angles around manganese of 90 degrees
62
what are the two shapes that can form from four coordinate complexes
* tetrahedral
* square planar
63
what is the tetrahedral complex
* bond angles of 109.5 degrees around the central metal ions
64
what are examples of tetrahedral complexess
* [CoCl4]2-
* [CuCl4]2-
65
what are square planar complexes
* occurs in complex ions of transition metals with eight d electrons in the highest energy d sub shell
* platinum (II), palladium (II) and gold (III) fall into this category and tend to form square planar complexes
* bond angle 90 degrees
66
give an examples of a sqare planar complex with platinum (II)
[Pt(NH3)2]2+
67
what are stereoisomers
* have the same structural formula but a different arrangement of atoms in space
68
what type of stereoisomeriam can transition metals show
* cis-trans isomerism
* optical isomerism
69
describe how different complexes show different types of steroisomerism
* some four coordinate and six coordinate complex ions containing two different mondentate ligands show cis - trans isomerism
* some six coordinate complex ions containing monodentate and bidentate ligands can show both cis trans and optical isomerism
70
what are the requirements for cis trans isomerism in complex ions
* no double bond is involved the shape of the complex holds groups in different orientations around the central metal ion
* cis trans isomerism occurs in some square planar and octahedral complex ions
71
describe cis trans isomerism in square plana complexes
* no ore than two identical ligand attatched to the central metal ion
* complex [Pd(NH3)2Cl2] formed from the Pd2+ ion, two NH3 ligands and two CL- ligands show cis trans isomerism
72
describe the arrangement of ligands in sqare planar complexes and how this helps to show cis trans isomerism
* ligands are arranged in the same plane at the corners of a square with 90 degrees bond angles
* in cis isomer the two identical groups are adjacent to each other
* whereas in trans isomer the two identical groups are opposite each other
* in cis isomer the coordinate bonds between the identical ligands are 90 degrees apart
* in the trans isomer the coordinate bonds between the identical ligands are 180 apart
73
describe how cis trans isomerism is show in octahedral complexes with monodentate ligands show how this is shown in [Co(NH3)4Cl2]2+
* contain four of one type of ligand and two of another type of ligand
* can exist as cis and trans isomers
* in cis isomer the two chloride ligands are adjacent to each other with their coordinate bonds seperate by 90 degrees
* whereas in the trans isomer the two chloride ligands are at opposite corners of the octahedrom with their coordiate bonds 180 dgrees apart
74
describe optical isomerism in octahedral complexes give an example
* only occurs in octahedral complexes containing two or more bidentate ligands
* the cis isomer with formula {Co(NH2CH2CH2NH2)2Cl2]+ can form optical isomerism
* but trans isomers cannot form optical isomers as mirror image is exactly the same and cannot be superimposed
75
what is an optical isomer
* called enantiomers
* are non superimposable mirror images of each othe
76
give an example of an optical isomer with three bidendate ligands
[Ru(NH2CH2CH2NH2)3]2+
77
what is ligand substitution reation
is one in which pne ligand in a complex ion is replaced by another ligand
78
describe what happens when copper (II) sulfate is dissolved in water
* pale blue complex ion [Cu(H2O)6]2+ is formed in aqueous solution
79
describe the formation of the pale blue solution to the dark blue solution when ammonia is added to [Cu(H2O)6]2+
* add ammonia drop wise to the solution
* a pale blue precipitate of Cu(OH)2 is formed in the first stage of the reaction
* the Cu(OH)2 precipitate then dissolved in excess ammonia to form a dark blue solution
80
describe ligand substitution reaction with ammonia with [Cu(H2O)6]2+ give an equation
* when an excess of aqueous ammonia is added to the solution containing [Cu(H2O)6]2+ the pale blue solution changes colour to form a dark blue solution
* [Cu(H2O)6]2+(aq)+4NH3(aq) ->[Cu(NH3)4(H2O)2]2+(aq) + 4H2O(l)
* in reaction four ammonia ligands have replaced four of the water ligands
* both [Cu(H2O)6]2+(aq) and [Cu(NH3)4(H2O)2]2+(aq) are octahedral complex ions
81
describe the ligand substitution reaction with chloride ions with [Cu(H2O)6]2+
* concentrated HCl used as a source of chloride ions
* when excess concentrated hydrochloric acid is added to a solution containing [Cu(H2O)6]2+ the pale blue solution changes colour to form a yellow solution
* six water ligands have been replaced with four chloride ligands
82
describe what happens id water is added to the yellow solution of [CuCl4]2-
* pale blue solution will be formed
* more dilute and paled in colour than the original blue solution
83
give the equation for the ligand substitution reaction between [Cu(H2O)6]2+(aq) and HCL
* reversible
* [Cu(H2O)6]2+(aq)+4Cl-(aq) -> {CuCl4]2-(aq) + 6H2) (l)
84
what happens to the coordination number and oxidation state and hape when [Cu(H2O)6 is added to concentrated HCL
* coordination number changes from 6 to 4
* shape changes from octahedral to tetrahedral
* oxidation state of copper remins as +2
* chloride ligands are larger in size than the water ligands so fewer chloride ligands can fit round the central Cu2+ ion
* explains the change in coordination number
85
describe how [Cr(H2O)6]3+ complexes are formed
* chromium (III) potassium sulfate KCr(SO4)2.12(H2O)
* also known as chrome alum is dissolved in water [Cr(H2O)6]3+ is formed
* this is a pale purple solution
* when chromium (III) sulfate is dissolved in water a green solution containing chromium (III0 is formed
* however the complex ions of [Cr(H2O)5SO4] wher eone of the water ligands has been replaced by a sulfate ion SO42-
* both purple and green solutions containing chromium (III) ions in oxidation state is 3
86
describe the reaction of ammonia with [Cr(H2O6]3+
* [Cr(H2O)6]3+ takes part in a ligand substituion reaction with an exess of aqueous ammonia forming the complex ion [Cr(NH3)6]3+
* when ammonia added drop wise to the chromium (III) solution the reaction takes place in two distinct steps
* intially a grey green precipitate of Cr(OH)3 is formed
* the Cr(OH)3 precipitate dissolved in excess ammonia to form the complex ion [Cr(NH3)6]3+
87
what is the reaction for when [Cr(H2)]3+ (aq) when it reacts with ammonia and what is the colour change
* [Cr(H2O)6]3+(aq) + 6NH3(aq) -> [Cr(NH3)6]3+(aq) + 6H2O(l)
* changes from violet to purple
88
describe what the function of haemoglobin and wht it consist of
* blood carries oxygen around the body due to the prescence of haemoglobin
* iron containing protein present in all red blood cells
* contains four protein chains held by weak intemolecules forces
* each protein chain has a haem molecule within its structure
* the central metal ion in a haem group is Fe2+ which can bind to oxygen gas O2
89
describe the function of haemoglobin in the body
* a blood passes through the lungs the haemoglobin bond to the oxygen becase of the increased oxygen pressure in the capillaries of the lungs
* a compound called oxyhaemoglbin forms which releases this oxygen to body cells as and when required
* in addition the haemoglobin in red blood cells can bond to the carbon dioxide which is carried back to the lungs
* carbon dioxide is then released from the red blood cells and carbon dioxide is exhaled
90
describe the ligand substitution of carbon monoxide
* carbon monoxide can bind to the Fe2+ ion in haemoglobin
* complex forms is carboxyhaemoglibin
* if carbon monoxide is breathed in a ligand substitution reaction takes place where the oxygen in haemoglobin is replaced by carbon monoxide
91
why is a small concentration of oxyhaemoglboin toxic
* carbon monoxide binds more strongly than oxygen so a small concentration of carbon monoxide in the lungs can prevent a large propertion of the haemoglobin molecules from carrying oxygen
* the bond is so strong that this process is irreversible
* if concentration of carboxyhaemoglobin becomes too high oxygen transport is prevented leading to death
92
what is a precipitation reaction
occurs when two aqueous solutions containing ions react together to form an insoluble ionic solid called a precipitate
93
describe how transition metal ions in aquoeus solution form precipitates
* react with aqueous sodium hydroxide and aqueous ammonia to form precipitates
* however some precipitates will dissolved in an excess of sodium hydroxide or ammonia to form complex ions in solution
94
describe the observation of Cu2+ with NaOH (aq) and equations
* blue solution reacts to form a blue precipitate of copper (II) hydroxide
* precipitate is insoluble in excess sodium hydroxide
* Cu2+(aq) + 2OH- (aq) ->Cu(OH)2 (s)
95
describe observations of Fe 2+ reacting with NaOH (aq) and any equations
* pale green solution reacts to form a green precipitate of iron (II) hydroxide
* the precipitate is insoluble in exess sodium hydroxide but turns brown at its surface on standing in air as iron (II) is oxidised to iron (III)
* Fe2+9aq) + 2OH-(aq) ->Fe(OH)2(s)
* in air :
* Fe(OH)2(s) -> Fe(OH)3 (s)
96
describe the observations when Fe3+ reacts with NaOH(aq) and equations
* pale yellow solution reacts to form an orange brown precipitate of iron(III) hydroxide
* precipirate is insoluble in excess sodium hydroxide
* Fe3+ (aq) + 3OH- aq) ->Fe(OH)3 (s)
97
describe the observations when Mn2+ reactis with aqueous NaOH(aq) and equations
* pale pink solution reacts to form a light brown precipitate of managanese (II) hydroxide which darkens on stnading in air
* the precipitate is insoluble in excess sodium hydroxide
* Mn2+ (aq) +2OH-9aq) -> Mn(OH)2 (s)
98
describe observations when Cr3+ reacts with NaOH(aq) and equations
* violet solution reacts to form a grey green precipitate of chromium (III) hydroxide
* the precipitate is soluble in excess sodium hydroxide forming a dark green solution
* Cr3+(aq) ->Cr(OH3)(s) -> [Cr(OH)6]3- (aq)
* Cr3+(aq) + 3OH- (aq) -> Cr(OH)3 (s)
* Cr(OH)3(s) +3OH-(aq) -> [Cr(OH)6]3-(aq)
99
describe a precipitation reactions with [Cu(H2O)6]3+ (aq) with aqueous excess ammonia
* Cu2+(aq) +2OH-(aq)->Cu(OH)2 (s)
* Cu(OH)2 (s) is a blue precipitate which dissolved in excess ammonia to form a deep blue solution with formula [Cu(NH3)4(H2O)2]2+ (aq)
100
describe the chromiu precipitation reaction with [Cr(H2O)6]3+(aq) with aquous ammonia
* Cr3+ (aq) + 3OH-(aq)->Cr(OH)3 (s)
* Cr(OH)3 is a green precipitate which dissolves in excess ammonia to form [Cr(NH3)6]3+ which is a purple solution
101
describe the reactions of Fe2+,Fe3+ and mN2+ with excess aquoeous ammonia
* react in sht e same way as aquous sodium hydroxide forming precipitates of Fe(OH)2 (s) , Fe (OH03 (s) and Mn (OH)2
* no further reaction with aquous ammonia so there precipitates do not dissolve
102
describe how a redox titration is done with iron (II) ion and manganate (VII) ions give an equatio
* Fe 2+ is oxidised to Fe 3+
* MNO42- is reduced to MN2+
* solution containing MNO4- ion is purple and is decolouried by Fe2+ (aq) ions to form a colourless solution contianing Mn2+ (aq) ions
* MnO4-(aq) +8H+ (aq) + Fe2+ (aq) -> Mn2+ (aq) + 5Fe3+ (aq) + 4H2O
103
describe the reduction of Fe 3+ to Fe 2+ inclue equations
* when a solution of Fe 3+ (aq) reacts with iodide ions I- (aq) the orange brown Fe 3+ (aq) ions are reduced to a pale green Fe 2+ 9aq) ions
* colour change is obscured by the oxidation of iodide ions to form iodine I2(aq) which has a brown colour
* 2Fe3+ (aq) + 2I-(aq) ->2Fe2+(aq) +I2(aq)
* Fe 3+ is reduced to Fe2+
* I- is oxidised to I2
104
describe how you can use standard electrod potentials to explain why the two redox reactions or iron ions above take place
* more positive E value
* equilibrium more likely to gain electrons shift to the right and undergo reduction
* for the reaction of Fe2+ and MnO4- in acid conditions:
* E for MnO4- / Mn2+ is more positive than for Fe3+/Fe2+
* so Fe 2+ is oxidised to Fe 3+ and MnO4- is reduced to Mn2+
* for the reaction of Fe3+ with I-:
* E for Fe3+/Fe2- is more positive than for I2/I-
* so I- is oxidised to I2 and Fe3+ is reduced to Fe 2+
105
describe the reduction reactions of dichromate (VI) to chromium (III) and write and equation and what happens if there is an excess of zinc
* aquoeus dichromate (VI) ion Cr2O72-(aq) have an orange colour and aquous chromium (III0 ions Cr3+ (aq) have a green colour
* acidified Cr2O72-(aq) ions can be reduced to Cr3+(aq) ions by the addition of zinc
* Cr2O72- (aq) +14 H+ (aq) = 3Zn (s) ->2Cr3+ (aq) + 7H2O (l) + 3Zn2+ (aq)
* with an excess of zinv chromium (III0 ions are reduced further to chromium (II) which is a pale blue colour
* Zn(s) + 2Cr3+ (aq) ->Zn2+ (aq) + 2Cr2+(aq)
106
describe why zinc is the most powerful reducing agent
* more positive e value going from Zn to Cr3+ to Cr2+
* equilibrium more likely to gain electrons shift to the right and undergo reduction
107
describe the oxidation of Cr3+ to CrO42- and how is it a redox reaction
* hot alkaline hydrogen peroxide H2O2 is a powerful oxidising agent and can be used to oxidise chromium (III0 in Cr 2+ to Chromium (VI) in CrO42-
* 3H2O2 + 2Cr3+ + 10OH- -> 2CrO4 2- + 8H2O
* chromium is oxidised from +3 in Cr 3+ to +6 in CrO4 2-
* oxygen is reduced from -1 in H2O2 to -2 in CrO42-
108
describe the reduction of Cu2+ to Cu+
* when aqueous copper (II) ions Cu2+ react with an excess of iodide ions I- (aq) a redox reaction occurs
* I- is oxidised to brown iodine I2
* Cu2+ is reduced to Cu+
* the Cu+ forms a white precipitate of copper (I) iodide
* 2Cu2+(aq) + 4I-(aq) ->2CUI (aq) +I2(s)
* pale blue solution forms a white precipitate of copper (I) iodide at the bottom of brown solution that forms
* white colour masked by brown iodine colour
109
describe a disproportionation reaction of Cu+ ions
* when solid copper (I) oxide Cu2O reacts with hot dilute sulfuric acid a brown precipitate of copper is formed together with a blue solution of copper (II) sulfate
* copper (I) ions Cu+ have veen simultaneously oxidised and reduced
* Cu2O(s) + H2SO4(aq) ->Cu(s) + CuSO2 (aq) + H2O(l)
110
what is disproporionation
same element has been reduced and oxidised
111
describe how transition metal ions can be identidies
adding sodium hydroxide producing precipitates with aquous transition metal ions
112
how was ammonium ions identified
* when heated with hydroxide ions NH4+ reacts to produce ammonia gas
* NH4+ (aq) + OH- (aq) -> NH39g) + H2O (l)
* to test for ammonium ion aqueous sodium hydroxide NaOH(aq) is heated gentl with solution being analysed
* if ammonia evolved damp red pH indicator paper will turn blue confirming the prescent of NH4+ ions
112
describe how carbonate ions are tested CO3 2-
* add dilute nitric acid HNO3(aq)
* effervesence as carbon dioxide is evolved
* Co32- (aq) + 2H+(aq) -> Co2(g) + H2O(l)
113
describe how sulfate ions are tested
* add Ba2+ (aq) ions
* white precipitate of BaSO4 is formed
* Ba2+(aq) + So42-(aq)->BaSO4(s)
114
describe how to test for halide ions
* add Ag+ (aq) ions
* white precipitate of AgCl if Cl- ions present soluble in dilute NH3 (aq)
* Ag+(aq)+Cl-(aq) ->AgCl (s)
* crea precipitateof AgBr if Br- ions present soluble in concentrate NH3(aq)
* yellow precipiate of AgI if I - ions present insoluble in NH3(aq)
