4. Inorganic chemistry Flashcards
1
Q
What is the trend in atomic radius down group 2?
A
atomic radius increases down the group
2
Q
Why does the atomic radius increase down group 2?
A
atoms have more shells of electrons making the atom bigger
3
Q
What is the trend in melting point down group 2?
A
melting point decreases
4
Q
Why does the melting point decrease down group 2?
A
the metallic bonding weakens as the atomic size increases.
The distance between positive ion and delocalised electrons increases.
therefore the electrostatic forces between the positive ions and delocalised electrons weaken.
5
Q
What is the trend in 1st ionisation energy down group 2?
A
.The outermost electrons are held more weakly because they are successively further from the nucleus in additional shells
.the outer shell electrons become more shielded from the attraction of the nucleus by the repulsive force of inner shell electrons
6
Q
What is the trend in reactivity down group 2?
why?
A
.reactivity increases
. atomic radii increase = more shielding
. the nuclear attraction decreases = easier to remove outer electrons and so cations form more easily
7
Q
How does Mg react with oxygen?
A
with a bright white flame
8
Q
What is the equation of Mg burning in oxygen?
A
2Mg + O2 —–> 2MgO
9
Q
What is MgO?
A
a white solid with a high melting point due to its ionic bonding
10
Q
Write an equation of a group 2 metal reacting with chlorine
A
Mg + Cl2 ——> MgCl2
11
Q
Write an equation for group 2 metals reacting with (cold) water with state symbols
A
Ca + 2 H2O (l) ——-> Ca(OH)2 (aq) + H2 (g)
12
Q
What would you observe when reacting group 2 metals with cold water?
A
.fizzing
.metal dissolving
.solution heating up
. Ca ONLY, a white ppt appearing (less ppt forms down the group)
13
Q
What group 2 metal wont react with cold water (l)?
What will it react with instead?
A
. magnesium
. reacts with water (g)
14
Q
Write the equation for Mg reacting with H20 (g) including state symbols.
A
Mg (s) + H2O (g) ——-> MgO (s) + H2 (g)
15
Q
What group 2 metal can react with (warm) water?
A
Magnesium
16
Q
Write the equation of magnesium with warm water
A
Mg + 2 H2O ——-> Mg(OH)2 + H2
17
Q
What do the group 2 oxides react with water to form?
A
hydroxides
18
Q
What do ionic oxides react as? why?
A
.Bronsted lowry bases
.as the oxide ions accept protons to become hydroxide ions
19
Q
Write an equation of a group 2 metal oxide with water. include symbols.
A
MgO (s) + H2O (l) ———> Mg(OH)2 (s)
20
Q
What does it mean if magnesium hydroxide is only slightly soluble in water? ( OH- and pH)
A
.fewer free OH- ions are produced
. so lower pH
21
Q
Write an equation of a group 2 oxide reacting with an acid. include state symbols.
A
SrO (s) + 2HCl (aq) ——-> SrCl2 (aq) + H2O (l)
CaO (s) + H2SO4 (aq) ——-> CaSo4 (aq) + H20(l)
22
Q
Write an equation of the group 2 hydroxides reacting with acids. include state symbols.
A
2HNO3 (aq) + Mg(OH)2 (aq) —-> Mg(NO3)2 (aq) + 2H2O (l)
23
Q
What is the trend in solubility of group 2 hydroxides down the group?
A
more soluble
24
Q
what do group 2 hydroxides appear as when not soluble?
A
white ppt
25
What group 2 hydroxides are classed as insoluble in water?
Beryllium and magnesium
26
A suspension of magnesium hydroxide in water will appear as what? therefore what has been produced?
.slightly alkaline pH 9
.so some hydroxide ions must therefore have been produced by a very slight dissolving
27
What is Magnesium hydroxide used as?
. as medicine to neutralise excess acid in the stomach and to treat constipation
28
Why is Magnesium hydroxide safe to use?
.because its so weakly alkaline
.it wont produce carbon dioxide gas (unlike calcium carbonate)
29
How soluble is calcium hydroxide in water?
reasonably soluble
30
What is calcium hydroxide used as?
. used in agriculture to neutralise acidic soils
31
What is an aqueous solution of calcium hydroxide classed as? and what can it be used to test?
. lime water
. used to test CO2, turns limewater cloudy as white calcium carbonate is produced.
32
How soluble in Barium hydroxide? What do the hydroxide ions make it?
.Very soluble
. makes solution strongly alkaline
33
What is the trend in solubility of group 2 sulfates down the group?
less soluble
34
What group 2 sulfate is the least soluble? Why?
. BaSO4
. If the barium metal is reacted with sulfuric acid it will only react slowly because as the insoluble barium sulfate produced will cover the surface of the metal and act as a barrier to further attack
35
Write the equation for Ba metal reacting with sulfuric acid.
Ba + H2SO4 -------> BaSO4 +H2
36
What do group 2 carbonates decompose on heating to produce?
Group 2 oxides and carbon dioxide gas
37
Write an equation of group 2 carbonates decomposing. Include state symbols
MgCO3 (s) ————> MgO (s) + CO2 (g)
38
What is the definition of thermal decomposition ?
The use of heat to/beak down a reactant into more than one product
39
What is the trend in thermal decomposition in group 2?
Decreases down he group
40
What is the trend in Group 2 carbonates thermal stability down the group ? Why ?
.More thermally stable
. As cations get bigger they have less of a polarising effect and distort the carbonate ion less.
.the C—O bond is weakened less so it easily breaks down
41
Why do group 1 carbonates not decompose (with exception of lithium) ?
.they only have a +1 charge = charge density is not big enough to polarise the carbonate ion
42
Why is lithium the only group 1 metal to thermaly decompose ?
Each the ion is small enough to have a polarising effect
43
What is the equation for the thermal decomposition of lithium ?
Li2CO3 (s) ————> li2O (s) + CO2 (g)
44
Explain one way to investigate the ease of thermal decomposition .
. heat a known mass of carbonate in a side arm boiling tuba and pass the gas produced through lime water.
. Time for the first permanent cloudiness to appear in the limewater
. Repeat for different carbonates using same moles of carbonate, same volume of limewater, same Bunsen burner flame and height of tube above flame
45
What do group 2 nitrates decompose on heating to produce?
Group 2 oxides, oxygen and nitrogen dioxide gas
46
What observation would you see when group 2 nitrates decompose ?
. Brown gas (from NO2)
. White nitrate solid mets to a colourless solution and then re-solidifies
47
Explain the why thermal stability increases down group 2.
.Magnesium nitrate decomposes the easiest because the Mg2+ ion is the smallest
. and it has a greater charge density
. it causes more polarisation on the nitrates anion
. and weakens the N-O bond
48
* Explain why potassium nitrate and calcium nitrate decompose to form different products. (3 marks)
. calcium ions have a 2+ charge whilst potassium ions have a 1+ charge.
. therefore calcium ions are more polarising / cause greater distortion
. of the N-O bond
49
What do group 1 nitrates decompose to give?
nitrate (III) salt and oxygen
50
write an equation for a group 1 nitrate decomposing.
2NaNO3 -----> 2NaNo2 + O2
51
write the equation for lithium nitrate decomposing.
4LiNO3 ------> 2Li2O + 4NO2 + O2
52
write a method for a flame test (3 marks)
. use a nichrome wire
.dip into conc. HCl
.dip into the sample
.heat in blue bunsen burner flame
53
Why do we use a nichrome wire?
because nichrome is an unreactive metal and will not give out any flame colour
54
Why do we dip the wire into concentrated HCl before use?
to clean the wire
55
* Explain how flame colours arise in a flame test (3 marks)
. heating promotes electrons to higher energy levels
. electrons fall back down to lower levers
. emitting visible light
56
* Suggest why the observations of the flame tests for magnesium chloride and calcium chloride are different (2 marks)
. In magnesium the energy levels are further apart
. For magnesium, the energy released is outside the visible spectrum
OR
. different wavelengths emitted
57
What 4 metals (G1+G2) have a red flame colour?
.lithium (scarlet)
.rubidium
.calcium (brick)
.strontium
58
What flame colour does Barium have?
apple green
59
What colour flame is sodium?
Yellow
60
what metal has a lilac flame?
potassium
61
what metal has a blue flame?
caesium
62
Why does magnesium have no flame colour?
the energy emitted of a wavelength outside visible spectrum
63
what is the trend in melting and boiling points in group 7? why?
.increases down the group
. as molecules become larger, they have more electrons = larger London forces
. as intermolecular forces get larger, more energy is required to break them
. increasing the mpt. and bpt.
64
What is electronegativity?
The relative tendency of an atom in a molecule to attract electrons in a covalent bond to itself
65
What is the trend in electronegativity down group 7? why?
.electronegativity decreases
. down group, atomic radii increases due to the increasing number of shells
. the nucleus is therefore less able to attract the bonding pair of electrons
66
What is the trend in reactivity down the halogens group?
.reactivity decreases
. as atoms get bigger with more shielding, they less easily attract and accept electrons
. they therefore form 1- ions less easily down the group
67
What is the trend in oxidising strength down group 7?
oxidising strength decreases
68
what are oxidising agents in terms of electrons?
they are electron acceptors
69
A halogen that is a strong oxidising agent will displace a halogen that...
has a lower oxidising power form one of its compounds
70
Therefore what halogen ions can chlorine displace?
Both bromide and iodide ions
71
what halogen will ONLY displace iodide ions?
bromine
72
What does the colour in the test tube show in a halogen displacement reaction?
which free halogen is present in solution
73
What does a very pale green solution (often colourless) tell you about what halogen is present in the solution during a displacement reaction?
chlorine
74
If bromine was present in a displacement reaction solution, what colour would be present?
yellow
75
If iodine was present in a displacement reaction solution, what colour would be present?
brown (sometimes black solid present)
76
In all reactions where halogens are reacting with metals, what is being oxidised?
metals
77
What two halogens can oxidise Fe2+ to Fe3+?
chlorine and bromine
78
Why can't iodine oxidise Fe2+ to Fe3+
iodine is not a strong enough oxidising agent to do this reaction.
the reaction is reversed for iodine
79
What is a disproportionation reaction?
When during reaction, an element is reduced and oxidised simultaneously
80
Write the equation for the disproportionation reaction when chlorine reacts with water. include state symbols.
Cl2 (g) +H2O (l) -----> HClO (aq) + HCl (aq)
81
What would be observed if some universal indicator is added to the reaction of chlorine with water? why?
. firstly, turn red (due to acidity of both products)
. then turn colourless ( as the HClO bleaches the colour)
82
What is the colour of the solution of chlorine and water? why?
. pale greenish
. due to the Cl2
83
What can Cl2 be used in?
. water treatment to kill bacteria
. treats drinking water and water in swimming pools
. benefits outweigh toxicity
84
Write the equation of halogens with hot dilute NaOH solution. including state symbols.
3Cl2 (aq) + 6NaOH (aq) -----> 5NaCl (aq) + NaClO3 (aq) + 3H2O (l)
85
Write the equation of halogens with cold dilute NaOH solution. including state symbols.
Cl2 (aq) + 2NaOH (aq) ------> NaCl (aq) + NaClO (aq) + H2O (l)
86
What is the name of this compound, NaClO?
sodium chlorate (I)
87
What is the the name of this compound, NaClO3?
Sodium chlorate (V)
88
What is the the name of this compound, K2SO4?
potassium sulfate (VI)
89
What is the the name of this compound, K2SO3?
potassium sulfate (IV)
90
What is the trend in reducing agent power down group 7? why?
.increasing power
. they have a greater tendency to donate electrons
. because as the ion gets bigger, it's easier for the outer electrons to be given away as the pull from the nucleus on them becomes smaller.
91
What is a reducing agent in terms of electrons?
They donate electrons
92
What reactions occur when conc. H2SO4 reacts with F- and Cl- ions? Why
. acid- base reactions
. H2SO4 is not a strong enough oxidising reagent to oxidise the ions
93
In the acid-base reactions, what role does the conc. H2SO4 play (in terms of acid and base)? why?
. role of an acid
. proton donor
94
Write an equation for either fluoride or chloride with conc. H2SO4. include state symbols.
NaF (s) + H2SO4 (l) ----> NaHSO4 (s) + HF (g)
NaCl (s) + H2SO4 (l) ----> NaHSO4 (s) + HCl (g)
95
What observations would you see when fluoride and chloride react with conc. sulfuric acid?
white steamy fumes of HCl / HF are evolved
96
are Br- ions stronger or weaker reducing agents than F- and Cl- ions?
stronger
97
With Br- ions, after the initial acid-base reaction what does it do to sulfur in the conc. H2SO4?
reduces it from +6 to +4 in SO2
98
Write the equation for the Acid base step when bromide reacts with conc. H2SO4. include state symbols.
NaBr (s) + H2SO4 (l) -----> NaHSO4 (s) + HBr (g)
99
Write the equation for the redox step when HBr reacts with conc. H2SO4. include state symbols.
2HBr (g) + H2SO4 (l) -----> Br2 (g) + SO2 (g) + 2H2O (l)
100
Write the oxidation half equation when bromide reacts with conc. sulfuric acid.
2Br- ------> Br2 +2e-
101
Write the reduction half equation when bromide reacts with conc. sulfuric acid.
H2SO4 + 2H+ + 2e- -----> SO2 + 2H20
102
What is the reduction product when HBr reacts with conc. sulfuric acid?
sulfur dioxide, SO2
103
What role does conc. H2SO4 play in the first step when reacted with bromide, producing HBr?
role of an acid
104
What role does conc. H2SO4 play in the second redox step when reacted with HBr?
oxidising agent
105
What observations would you make when bromide reacts with conc. sulfuric acid?
. white steamy fumes of HBr are evolved
. red fumes of bromine are also evolved
. a colourless acidic gas SO2
106
What is the strongest halide reducing agent out of F-, Cl-, Br-, and I- ions?
I- ions (iodide)
107
How much does iodide reduce the conc. sulfur in H2SO4? (4 different oxidation no.)
. H2SO4 = +6
. to +4 in So2
. to 0 in S
. and -2 in H2S
108
Write an equation for the first step of iodide reacting with sulfuric acid. include state symbols.
NaI (s) + H2SO4 (l) -----> NaHSO4 (s) + HI (g)
109
Write an equation for the second step of iodide reacting with sulfuric acid. include state symbols.
2HI (g) + H2SO4 (l) -----> I2 (s) + SO2 (g) + 2H2O (l)
110
Write an equation for the third step of iodide reacting with sulfuric acid. include state symbols.
6HI (g) + H2SO4 -----> 3I2 (s) + S(s) + 4H2O (l)
111
Write an equation for the last step of iodide reacting with sulfuric acid. include state symbols.
8Hi (g) + H2SO4 (l) -----> 4I2 (s) + H2S (g) + 4H2O (l)
112
what is the oxidation half equation when bromide reacts with sulfuric acid?
2I- ------> I2 + 2e-
113
what are the 3 reduction half equations when bromide reacts with sulfuric acid?
. H2SO4 + 2H+ + 2e- -----> SO2 + 2H2O
. H2SO4 + 6H+ + 6e- -----> S + 4H2O
. H2SO4 + 8H+ + 8e- -----> H2S + 4H2O
114
What role does conc. H2SO4 play in the first step when reacted with iodide, producing HI?
role of an acid
115
What role does conc. H2SO4 play in the 3 redox steps when reacted with iodide?
acts as an oxidising agent
116
What are the reduction products when iodide reacts with conc. sulfuric acid?
sulfur dioxide, sulfur, and hydrogen sulfide
117
What observations are made when iodide reacts with conc. sulfuric acid?
. white steamy fumes of HI are evolved
. Black solid and purple fumes of iodine are evolved
. A colourless, acidic gas SO2
. A yellow solid of sulphur
. H2S (hydrogen sulphide), a gas with a bad egg smell
118
What test can be used to identify which halide ion is present?
halide ions with silver nitrate
119
What is the role of nitric acid when halide ions are reacted with silver nitrate?
. to react with any carbonates present to prevent formation of the precipitate Ag2CO3
120
What are the desired observations when halide ions are reacted with silver nitrate?
2HNO3 + Na2CO3 -----> 2NaNO3 + H2O + CO2
121
How is the test solution made when halide ions react with silver nitrate? (before adding the halide ions)
. 1st the solution is made acidic with nitric acid
. then silver nitrate solution is added dropwise
122
What observation would you make when fluorides react with silver nitrate?
no precipitate
123
What observation would you make when chlorides react with silver nitrate? include an equation with state symbols.
. white precipitate
. Ag+ (aq) + Cl- (aq) -----> AgCl (s)
124
What observation would you make when bromides react with silver nitrate? include an equation with state symbols.
.cream ppt
. Ag+ (aq) + Br- (aq) -----> AgBr (s)
125
What observation would you make when iodides react with silver nitrate? include an equation with state symbols.
. pale yellow ppt
. Ag+ (aq) + I- (aq) -----> AgI (s)
126
What is the effect of light on silver halides? Which is the exception? What is this reaction used for?
. the ppts darken in sunlight forming silver
. AgI is the exception
. used in photography to form the dark bits on photographic film
127
What is used to differentiate between the silver halide precipitates?
ammonia solution
128
What does silver chloride dissolve in? what does it form?
. dilute ammonia
. a complex ion [Ag(NH3)2]+ (aq) and Cl- (aq)
129
What does silver bromide dissolve in? what does it form?
. conc. ammonia
. a complex ion [Ag(NH3)2]+ (aq) and Br- (aq)
130
What colour is the solution of [Ag(NH3)2]+ (aq)?
. it's a colourless solution
131
Why does silver iodide not react with ammonia?
it's too insoluble
132
How are hydrogen halides produced?
by the reaction of solid sodium halide salts with phosphoric acid
133
Write the equation to make hydrogen halides. include state symbols.
NaCl (s) + H3PO4 (l) -----> NaH2PO4 (s) + HCl (g)
134
What observations would be made when producing hydrogen halides?
. white steamy fumes of the hydrogen halides are evolved
135
Why are the steamy fumes of HCl produced when making hydrogen halides?
because when the HCl meets the air, it dissolves in the moisture in the air
136
What is the more suitable method for producing hydrogen halides, H3PO4 or conc. H2SO4? why?
. phosphoric acid
. because there are no extra redox reactions taking place and no other products formed
137
Why does phosphoric acid not oxidise the HBr and HI?
because H3PO4 is not an oxidising agent
138
hydrogen halides are more dense than what?
air
(therefore a downward delivery is used in the apparatus)
139
Are hydrogen halides soluble in water?
All hydrogen halides ARE SOLUBLE in water
140
What do hydrogen halides form with water? write an equation, including state symbols.
. dissolve to form acidic solutions
HCl (g) + H2O (l) -----> H3O+ (aq) + Cl- (aq)
141
What can be used to test for presence of hydrogen halides?
hydrogen halides reacting with AMMONIA
142
Write an equation of a hydrogen halide reacting with ammonia. include state symbols.
HCl (g) + NH3 (g) ------> NH4Cl (s)
143
How do you test for presence of carbonates and hydrocarbonates? Observations?
.add any dilute acid
. observe effervescence from CO2
144
How do you test for carbon dioxide? observations?
. bubble gas through limewater
. will turn limewater cloudy
145
Write an equation for the test of carbonates/ hyrdocarbonates.
. 2HCl + Na2CO3 -----> 2NaCl + H2O + CO2
. HCl + NaHCO3 -----> NaCl + H2O + CO2
146
How do you test for a presence of a sulfate? Observations?
. acidified BaCl2 solution is used as a reagent to test for sulfate ions
. if ions present, white ppt forms
147
Write the ionic equation for BaCl2 and a sulfate. include state symbols.
Ba2+ (aq) + SO4 2- (aq) ------> BaSO4 (s)
148
Why is the acid needed in acidified BaCl2?
. to react with any carbonate impurities that are often found in salts
. they would form a white barium carbonate ppt and so give a false result
149
Why can sulfuric acid not be used to acidify the mixture instead of acidified BaCl2? What would be observed?
.because it contains sulfate ions
.which would form a ppt
150
How do you test for ammonium ion, NH4+? what would form?
.by reaction with warm NaOH (aq)
. forming NH3
151
What is the ionic equation for test for ammonium ion?
NH4+ + OH- -----> NH3 + H2O
152
how can ammonia gas be identified?
its pungent smell or by turning damp red litmus paper blue
153
What is the appearance of iodine when solid?
shiny grey
154
What is the appearance of iodine when dissolved in aqueous potassium iodide?
brown
155
What is the appearance of iodine when dissolved in a liquid hydrocarbon?
purple
156
True or False, going down group 7, the polarity of the hydrogen halide bond increases?
FALSE, polarity decreases.
157
* Explain why the boiling temperatures increase from chlorine to iodine (2 marks)
. from chlorine to iodine the number of electrons increases from 17 to 53
. so the strength of the London forces increases AND more energy is needed to separate the molecules
158
* By referring to any changes in oxidation numbers when these halides react with concentrated sulfuric acid, explain which is the strongest reducing agent. (3 marks)
. Iodide ions are the strongest reducing agent because iodide ions reduces sulfur (in H2SO4) from +6 to 0 in sulfur/ -2 in H2S
. whereas bromide ions reduces sulfur (in H2SO4) from +6 to +4
. Chloride ions do not reduce sulfuric acid (as there is no change in oxidation number of Cl or S)
159
