Inorganic Flashcards
What is the trend in atomic radius across a period?
Atomic radius decreases because they have similar shielding but more protons so there is a stronger attraction between outer electrons and the nucleus causing the atomic radius to be reduced
What is the trend in atomic radius down a group?
Atomic radius increases because an electron shell is added with every element which increases the distance and shielding between the outer electrons and nucleus, reducing the nuclear attraction
What is the general trend in ionisation energies across the period?
Increases as atomic radius is decreasing and nuclear charge is increasing meaning the outer electrons are held more strongly so more energy required
Why does the ionisation energy drop a bit between Mg (3s2) and Al (3s2 3p1)?
There is an increase in shielding and 3p orbital has a slightly higher energy level so the electron is on average further from the nucleus meaning electron motor easily lost
Why does the ionisation energy drop a bit between P (3s2 3p3) and S (3s2 3p4)?
Have same shielding but in Sulphur electron is being removed from an orbital containing two electrons so the repulsion between the electrons makes it easier to remove
What are the different types of bonding in period 3?
Na, Mg, Al, Si, P, S, Cl, Ar
Na, Mg, Al - metallic
Si - macromolecular (covalent)
P, S, Cl - simple molecular
Ar - monatomic
What is the trend in melting points from Na, Mg and Al?
Increases as you go across because the nuclear charge and no. of delocalised electrons per ion is increasing so there is greater attraction
What is the trend in melting points from P, S, Cl?
P4 S8 Cl2
S has highest melting point as has highest Mr so has the strongest VDW of the three where as Cl has the weakest
Why does Ar have the lowest melting point in period three?
Full outer shell of electrons so atom very stable and only has very VDW forces between them
What is the trend in melting points down group 2?
Decreases as they all have two delocalised electrons per ion but the size of the metallic ion increases down the group meaning the attraction becomes weaker as has to act over a greater distance
What type of reaction happens between water and group 2 metals?
redox
What is the reaction between group 2 metals and water?
M + 2H2O –> M(OH)2 + H2
Which group 2 metal reacts differently with steam?
magnesium
What is the reaction between magnesium and steam?
Mg + H2O (g) –> MgO (s) + H2 (g)
What is the trend in reactivity down group 2?
Reactivity increases as IE decreases meaning it becomes easier to oxidise atoms
What is the trend in solubility of group 2 metal hydroxides down the group? (what is the most soluble)
solubility increases - Ba(OH)2 is the most soluble
What is the trend in solubility of group 2 metal sulphates? (what is the most soluble)
solubility decreases - MgSO4 most soluble
How is Mg(OH)2 used and why?
Used as an antiacid (indigestion tablets) as its insoluble and neutralises acid
How is Ca(OH)2 used?
Used in agriculture to neutralise acidic soil
How is BaSO4 used and why?
Used as a barium meal (type of medical tracer). Toxic when enters the bloodstream but as its insoluble it can’t be absorbed
How do you test for sulfate ions? (SO4 2-)
Add acidified barium chloride (BaCl2 + HCl) and positive result is white ppt formed
Why is barium used to test for SO4 2- ions?
most insoluble group 2 sulphate
Why must barium chloride be acidified when testing for sulfate ions?
remove any sulphite or carbon impurities
What is the equation for the reaction between barium chloride and sulfate ions?
BaCl2 + XSO4 –> BaSO4 + 2XCl
How is titanium extracted from titanium chloride (TiCl4)?
magnesium
What type of reaction is the extraction of titanium from titanium chloride using magnesium?
displacement
What is the role of magnesium in the extraction of titanium from titanium chloride?
reducing agent (electron donor)
What is the equation for the extraction of titanium from titanium chloride using magnesium?
TiCl4 + 2Mg –> 2MgCl2 + Ti
What is flue gas?
gases emitted from industrial exhausts and chimneys (SO2 sulphur dioxide)
How do we prevent flue gases entering the atmosphere?
using CaO (lime) or CaCO3 (limestone)
What is the reaction when CaO is used to remove flue gases (SO2)? What is the product called
CaO (s) + 2H2O (l) + SO2 (g) –> CaSO3 (s) + 2H2O
CaSO3 = calcium sulfite
What is the reaction when CaCO3 is used to remove flue gases (SO2)?
CaCO3 (s) + 2H2O (l) + SO2 (s) –> CaSO3 (s) + 2H2O + CO2 (g)
What do you observe when you react group 2 metal with excess water?
colourless solution and effervescence
What is the trend in solubility of group2 metals in water?
Solubility increases down group
Ba most soluble
Why do isotopes have same chemical properties?
same electron configuration
What is the trend in atomic radius down group 7?
increases down group due to additional electrons shells
What is the trend in reactivity down group 7?
Reactivity decreases down group as increased size and shielding makes it harder to gain electrons
What is the trend in ionisation energy down group 7?
decreases due to increased atomic radius and shielding
What is the trend in boiling points down group 7?
They’re simple covalent molecules which are held together by VDW so bp increases down group as Mr increases meaning VDW are stronger
What state are the halogens at room temperature?
F gas
Cl gas
Br liquid
I solid
What is the trend in electronegativity down group 7?
decreases down the group as atomic radius and shielding increases making them worse at attracting the shared pair of electrons
What is the trend in oxidising power (ability as an oxidising agent) of halogens down the group?
Oxidising power (ability to accept electrons) decreases down the group as their ability to attract electrons decreases due to the increase in atomic radius and shielding.
When will a halogen displace a halide?
If the halide is beneath it
So Cl2 will displace Br-
Are the halide ions good reducing agents or oxidising agents?
reducing agents because they are good at donating electrons
What is the trend in the reducing power of halides down the group?
reducing power increases as electrons are more easily lost from larger ions
What is the reaction between Fluoride ions and sulphuric acid and what’s the observations? Is it redox?
NaF + H2SO4 –> NaHSO4 + HF
misty white fumes of HF
not redox
What is the reaction between Chloride ions and sulphuric acid and what’s the observations? Is it redox?
NaCl + H2SO4 –> NaHSO4 + HCl
misty white fumes of HCl
not redox
What is the reaction between Bromide ions and sulphuric acid and what’s the observations? Is it redox?
NaBr + H2SO4 –> NaHSO4 + HBr
misty white fumes of HBr
not redox
2HBr + H2SO4 –> Br2 + SO2 + 2H2O
chocking fumes SO2
brown fumes Br2
redox
What is the reaction between Iodide ions and sulphuric acid and what’s the observations? Is it redox?
NaI + H2SO4 –> NaHSO4 + HI
misty white fumes of HI
not redox
2HI + H2SO4 –> I2 + SO2 + 2H2O
chocking fumes SO2
black solid I2
redox
6HI + SO2 –> H2S + 3I2 + 2H2O
bad egg smell H2S
redox
Why does the HCl and HF produced from reacting halides with sulphuric acid not react further?
Aren’t strong enough reducing agents
How do you test for halides?
add dilute HNO3
add few drops of AgNO3
double check by adding ammonia solution
Why do you add dilute nitric acid when testing for halides?
To remove any ions that might interfere with the test
Why do we use AgNO3 when testing for halides?
Reacts to form a different coloured ppt depending on what ion is present
What is the ionic equation the test for halides?
Ag+ + X- —> AgX (s)
Why do you use ammonia solution when testing for halides?
silver halides have different solubilities
What happens when you add NH3 (aq) to silver halides?
chloride - dissolves in dilute
bromide - dissolves in conc.
iodide - insoluble
What is the reaction of chlorine and cold water?
Cl2 (g) + H2O (l) –> HClO + HCl
HClO is chlorate ions
What type of reaction is the reaction of chlorine and water to make chlorate and chloride ion and why?
disproportionation as chlorine is both oxides and reduced
ClO- and Cl-
What is the reaction of chlorine and water in the presence of UV light?
2Cl2 + 2H2O –> 4HCl + O2
What do we do with chlorate ions and why?
Added to water to make it drinkable and to pools as kills bacteria
What are the benefits of chlorinated water?
Kills disease causing microorganisms
Can persist in the water and prevent infection further down the supply
Prevents growth of algae, eliminating bad tastes and smells
Removes discolouration caused by organic compounds
What are the risks of chlorinated water?
Chlorine gas is very harmful if breathed in, irritates respiratory system
Liquid chlorine can cause burns
Chlorine reacts with a variety of organic compounds and forms carcinogenic (cancer causing) chlorinated hydrocarbons
What do you react chlorine with to make bleach?
cold, aqueous NaOH
What is the reaction between sodium hydroxide and chlorine to make bleach?
2NaOH + Cl2 –> NaClO + H2O + NaCl
What is the overall reaction between solid sodium bromine and conc. sulfuric acid?
2NaBr+2H2SO4 →Na2SO4 +Br2 +SO2 +2H2O
What is more reative sodium or magnesium?
Sodium as when it reacts it forms +1 ion so requires less energy to lose one electron as opposed to the two of magnesium
What are some observation when sodium reacts with cold water?
vigorous reaction, forms a molten ball on the surface of the water
fizzing, prodding H2 (g)
How alkaline is the solution after magnesium reacts with cold water?
Mg(OH)2 weakly alkaline as not vary soluble so few OH- ions
pH = 9-10
Observations when magnesium reacts with cold water?
reacts very slowly, thin coating of Mg(OH)2 forms on the surface of the metal
What is the oxide formed with Na and how does it react? and type of bonding?
Na2O
vigorous
ionic
What is the oxide formed with Mg and how does it react? and type of bonding?
MgO
vigorous
ionic
What is the oxide formed with Al and how does it react? and type of bonding?
Al2O3
slow (faster if powdered)
ionic (partially covalent)
What is the oxide formed with Silicon and how does it react? and type of bonding?
SiO2
slow
giant covalent structure (macromolecular)
What is the oxide formed with phosphorus (V) and how does it react? and type of bonding?
P4O10
spontaneously combusts
simple molecular
What is the oxide formed with sulphur and how does it react? and type of bonding?
SO2
burns steadily
simple molecular
(add vanadium catalyst and you get SO3)
Explain trend in melting points of period 3 metal oxides? Na, Mg, Al
All have high m.p as they form giant ionic lattices
Mg higher than Na as +2 ions from stronger bonds
Al lower than Mg as small electronegaitivty difference between Al and O so oxygen ions don’t attract the electrons as strongly making the bond partially ionic
Why does Al2O3 have a lower mp than expected?
Small electronegativity difference between Al and O means oxygen ions don’t attract electrons as strongly making the bonds partially covalent
Why are mp of P4O10 and SO2 significantly lower than that of other period 3 oxides?
simple molecular structures so only have weak VDW
Reaction of P4O10 and water?
P4O10 (s) + 6H2O –> 4H3PO4
(phosphoric acid)
Reaction of SO2 and water?
SO2 (g) + H2O –> H2SO3
(sulphurous acid)
Reaction of SO3 and water?
SO3 (l) + H2O –> H2SO4
(sulfuric acid)
Why is SiO2 insoluble in water?
giant covalent structure but it is still acidic as can neutralise a base
Why is Al2O3 insoluble in water?
as its partially covalent (needs to be polar)
What does amphoteric mean?
can act as an acid or a base
Does Al2O3 act as a base or an acid?
both its amphoteric
How does SiO2 neutralise sodium hydroxide?
SiO2 (s) + 2NaOH –> Na2SiO3 + H2O
How does P4O10 neutralise sodium hydroxide?
P4O10 (s) + 12 NaOH –> 4Na3PO4 + 6H2O
How does SO2 neutralise sodium hydroxide?
SO2 (g) + 2NaOH –> Na2SO3 + H2O
How does SO3 neutralise sodium hydroxide?
SO3 (g) + 2NaOH –> Na2SO4 + H2O
How does Al2O3 act as a base?
Al2O3 (s) + 3H2SO4 –> Al2 (SO4)3 + 3H2O
How does Al2O3 act as an acid?
Al2O3 (s) + 2NaOH + 3H2O –> 2Na Al (OH)4
What are transition metals?
Elements in the d block of the periodic table with a partially filled d orbital
What are the physical properties of transition metals?
high densities
high mp and bp
ionic radii are pretty much the same
(all have similar physical properties)
What are the chemical properties of transition metals?
Can from complex ions
Form coloured ions
Good catalysts
Exist in variable oxidation states
What is a complex?
Central metal atom or ion surrounded by co-ordinately bonded ligands
What is a ligand?
atom/ion/molecule that donates a pair of electrons to a central transition metal ion to form a co ordinate bond
What is a coordination number?
No. of coordinate bonds bonded to central metal atom/ion
What is the shape of a 6 coordinate bond complex and an example?
Octahedral
[Fe(H2O)6] 2+ (aq)
What is the shape of a 4 coordinate bond complex and an example?
Tetrahedral
[CuCl4] 2-
What is the shape of a 2 coordinate bond complex and an example?
linear
[Ag(NH3)2] + (tollens reagent)
What is Tollens reagent and how is it used?
[Ag(NH3)2] +
test to distinguish between aldehydes and ketones
What is the oxidation state of the central metal ion of a complex ion?
(total ox. state of complex) - (ox. state of all ligands)
What must a ligand have in order to form a coordinate bond?
At least one lone pair
What are ligands that only from one coordinate bond called and give examples?
monodentate
NH3, H2O, Cl-
What are ligands that form two coordinate bonds called and give examples?
bidentate
ethane - 1,2 - diamine :NH2CH2CH2:NH2
ethanedioate ions O:OCCOO:
What are ligands that form more than two coordinate bonds called and give examples?
multi dentate
EDTA 4-
What is the central transition metal ion in haemoglobin?
Fe 2+
What its haemoglobin?
A protein found in blood that helps to transport oxygen around the body
What is the Haem part of Haemoglobin?
Four nitrogen’s coordinately bonded to a Fe 2+ which all come from same multidentate ligand
What is the globin part of haemoglobin?
The other two coodrinate bonds in haemoglobin come from either water or oxygen and then a protein called groin which has a lone pair on a nitrogen that can coordinately bond to the Fe 2+
How does haemoglobin carry oxygen round the body?
In the lungs (where oxygen conc. is high) an oxygen molecule is substituted for the water ligand and bonds coordinately to the Fe 2+ to from oxyhemoglobin which is then 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 then it returns to the lungs to repeat the process again
What happens to haemoglobin when CO is inhaled?
The haemoglobin swaps its water ligand for a carbon monoxide ligand forming carboxyhemoglobin. CO is a strong ligand so doesn’t swap with water or oxygen molecules meaning the haemoglobin can no longer transport oxygen so CO poisoning starves the organs of oxygen
What happens when a ligands substituted or exchanged?
usually a colour change
How do you form a more stable complex?
Multidentate ligand instead of mono dentate ones
When is a reaction not reversible (complex ions)?
If new ligand form stronger bonds
What is the Chelate effect?
Positive entropy change is favourable so monodenatate lingands are substituted with bidentate and multidentate ligands (more moles on RHS)
eg [Fe (H2O)6]3+ + EDTA 4- –> [Fe (EDTA)]- +6H2O) more moles formed so favourable
What types of isomerism can complex ions show and when do they occur?
optical isomerism - when octahedral complexes have three bidentate ligands co.ord bonded
cis-trans isomerism (special type of EZ) - octahedral and square planar complexes
both types of stereoisomerism
What is an example of square planar isomerism and what is it called?
transplatin and cisplatin
Pt central ion with two NH3 and two Cl-
EZ stereoisomerism
How is cisplatin used and what are the side effects?
Anti-cancer drug
hair loss
When oxidation sate of vanadium is +5 what is the ion formula and ion colour?
VO2 +
yellow
When oxidation sate of vanadium is +4 what is the ion formula and ion colour?
VO (2+)
blue
When oxidation sate of vanadium is +3 what is the ion formula and ion colour?
V 3+
green
When oxidation sate of vanadium is +2 what is the ion formula and ion colour?
V 2+
violet
What is the enthalpy change for ligand substitution reactions like?
enthalpy change is small as bonds being formed are very similar to the bonds that were broken
How are the different oxidation states of vanadium produced?
Oxidation of vanadium by zinc in acidic solution
What determines weather a transition metal is oxidised or reduced?
pH
What is required for ions to be reduced?
acidic conditions
How can you identify a transition metal ion?
its colour
What does the colour of a transition metal ion complex depend on?
coordination number
type of ligands
oxidation state of transition metal
How does colour arise in transition metals?
When some of the wavelengths of visible light are absorbed and the remaining wavelengths are reflected and transmitted to the human eye. The reflected wavelengths correspond to a specific colour
What happens to d electrons when light is absorbed?
move from the ground state to an excited state as they’ve gained energy
How do you calculate the energy change of electrons when they are excited?
E = hf
f is the frequency of light emitted
h is planck constant
What is colorimetry?
An analytical technique that uses absorption of visible light to determine the conc. of coloured ions by measuring absorbance
How do you find the conc. of a coloured solution using a colorimeter?
White light is shone through a filter (which has been chosen so that it only lets through the colour of light that is absorbed by the sample)
The light then passes through the sample to the colorimeter which calculates how much light was absorbed by the sample
The more concentrated the solution the more light it will absorb
You can then use a calibration curve (which is made by measuring the absorbance of known concentrations) and then read off the graph
Why are the energies of the d orbitals of the metal ion raised when ligands are bonded to it and what happens to the d orbitals?
Because of the repulsion between the electrons in the ligands and the electrons in the d orbitals of the metal ions.
However cause of how they’re arranged in space it doesn’t raise all their energies by the same amount. Instead it splits them into two groups
What is a heterogeneous catalyst and give an example?
A catalyst that is in a different phase or state to the species in the reaction
Iron catalyst in the Haber process
Why do transition metals make good catalysts?
Variable oxidation states
electrons are transferred to produce a reactive intermediate and speed up the reaction rate
What is the overall reaction for the Contact Process?
2SO2 + O2 –> 2SO3
V2 O5 catalyst
What are the intermediate reactions in the Contact Process?
V2O5 + SO2 –> V2O4 + SO3
V2O4 + 1/2 O2 –> V2O5
What is a homogenous catalyst?
A catalyst that is in the same phase/state as the species in the reaction
How does a heterogenous solid catalyst work?
adsorbs molecules onto an active site on the surface of the catalyst
How does adsorption work?
It adsorbs different species to the active site and increases the proximity of molecules and weakens the covalent bonds in the molecules so that reactions occur more easily and the rate is increased
What does the strength of adsorption depend on?
Type of catalyst
Why do iron, cobalt and nickel make the best catalysts?
relatively cheap and increase the rate of reaction the most out of period 4 metals
What type of catalysts can be poisoned by impurities?
heterogenous
What is catalyst poisoning?
When impurities block the adsorption site preventing adsorption
which means bonds of molecules remain strong and the catalyst has no effect on the rate of reaction
What is the problem with catalyst poisoning?
means an increase in chemical production costs as catalyst has to be replaced or cleaned regularly
What impurities poison the solid iron catalyst used in the Haber process?
sulfur impurities
What impurities poison the rhodinium in catalytic converters?
lead
What is a catalytic converter?
Turns toxic gases and pollutants into less harmful gases
Equation for catalytic converter and catalyst used? (CO and NO)
2CO (g) + 2NO (g) –> 2CO2 (g) + N2 (g)
solid rhodinium and platinum
How do catalytic converters get poisoned?
When leaded petrol is used, the lead sticks to the catalytic converters so theyre no longer effective
Why does S2O8 (2-) and I- need a catalyst to react?
Both anions so would naturally repel and never react
What catalyst is used when reacting S2O8 (2-) and I-?
Fe 2+ or Fe 3+
Overall reaction between S2O8 (2-) and I-?
2S2O8 (2-) + 2I- –> I2 + 2SO4 (2-)
Fe 2+ or Fe 3+ catalyst
What are the intermediate reactions of S2O8 (2-) with I -?
S2O8 (2-) + 2Fe 2+ –> 2SO4 (2-) + 2Fe 3+
2Fe 3+ + 2I- –> 2Fe 2+ + I2
can happen in any order hence why both Fe2+ and Fe3+ can be used
What is autocatalysis?
When something catalyses itself
How do homogenous catalysts work?
They work by combining with the reactants to produce a reactive intermediate. This changes the reaction path as the enthalpy change for the formation of the intermediate is much lower than the original reaction.
So activation energy is lower and the reaction is more feasible
What happens to the rate of reaction when something is an autocatalyst?
As the amount of product increases the rate of reaction increases as it becomes catalysed
What is the autocatalyst when MnO4 - and C2O4 (2-) react?
Mn 2+
What is the overall reaction between MnO4 - and C2O4 (2-)?
2MnO4- + 5C2O4 (2-) + 16H+ –> 2Mn2+ + 10CO2 + 8H2O
What are the intermediate reactions of the reaction between MnO4- and C2O4 (2-) where Mn2+ acts as an autocatalyst?
4Mn2+ + MnO4- + 8H+ –> 5Mn3+ + 4H2O
2Mn3+ + C2O4 (2-) –> 2CO2 + 2Mn2+
What increases efficiency of heterogenous catalysts?
larger surface area by using powder or coating mesh with the catalyst
