Download AQA Chemistry A-Level Exam Study Guide: Transition Metals, Catalysis, and Redox Reactions and more Exams Chemistry in PDF only on Docsity!
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
What makes transition metal characteristics - ansincomplete d sub-level in atoms or ions 4 main characteristics of Transition metals - anscomplex formation, formation of coloured ions, variable oxidation state, catalytic activity what is a complex - ansa central metal ion surrounded by ligands what is a ligand - ansAn atom, ion or molecule which can donate a lone electron pair what is a coordinate bond - ansCo-ordinate bonding is when the shared pair of electrons in the covalent bond come from only one of the bonding atoms what is coordination number - ansThe number of co-ordinate bonds formed to a central metal ion why is carbon monoxide toxic - ansCO is toxic to humans as CO can from a strong coordinate bond with haemoglobin. This is a stronger bond than that made with oxygen and so it replaces the oxygen attaching to the haemoglobin what is the chelate effect - ansThe substitution of monodentate ligand with a bidentate or a multidentate ligand leads to a more stable complex. This chelate effect can be explained in terms of a positive entropy change in these reactions as more molecules of products than reactants type of isomerism shown in square planar/octahedral complexes - ansE-Z isomerism shown only in octahedral complexes - ansComplexes with 3 bidentate ligands can form two optical isomers (non-superimposable mirror images) how do transition metals show colour - ansColour arises from electronic transitions from the ground state to excited states: between different d orbitals. A portion of visible light is absorbed to promote d electrons to higher energy levels. The light that is not absorbed is transmitted to give the substance colour. what is the equation which links the colour and frequency of the light absorbed with the energy difference between the split d orbitals - ansE = hv. v = frequency of light absorbed (unit s-1 or Hz) h= Planck's constant 6.63 × 10-34 (J s) E = energy difference between split orbitals (J) how can you change colour of transition metals - ansChanging a ligand or changing the coordination number will alter the energy split between the d- orbitals, changing E and hence change the frequency of light absorbed describe the method of spectroscopy - ans•Add an appropriate ligand to intensify colour •Make up solutions of known concentration (dilution series) •Measure absorption or transmission •Plot graph of absorption vs concentration •Measure absorption of unknown and compare general trend of variable oxidation states - ans- Relative stability of +2 state with respect to +3 state increases across the period
- Compounds with high oxidation states tend to be oxidising agents e.g MnO4--Compounds with low oxidation states are often reducing agents e.g V2+ & Fe2+ four colour and symbol stages of Vanadium - ansVO2+ Oxidation state +5 ( a yellow solution) VO2+ Oxidation state + 4 (a blue solution) V3+ Oxidation state + 3 (a green solution) V2+ Oxidation state + 2 (a violet solution)
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
YOU BETTER GET VANADIUM
what is used to reduce vanadium - ansAddition of zinc to the vanadium (V) in acidic solution will reduce the vanadium down through each successive oxidation state, and the colour would successively change from yellow to blue to green to violet what is used in testing for aldehydes - ans[Ag(NH3)2]+ is used in Tollen's reagent to distinguish between aldehydes and ketones. Aldehydes reduce the silver in the Tollen's reagent to silver why are dark colours of solutions difficult to measure - ansThe purple colour of manganate can make it difficult to see the bottom of meniscus in the burette. what acid is used for manganate titrations - ansOnly use dilute sulphuric acid for manganate titrations. Insufficient volumes of sulphuric acid will mean the solution is not acidic enough and MnO will be produced instead of Mn2+. Using a weak acid like ethanoic acid would have the same effect as it cannot supply the large amount of hydrogen ions needed (8H+). It cannot be conc HCl as the Cl- ions would be oxidised to Cl what is a heterogenous catalyst - ansin a different phase from the reactants what is a homogenous catalyst - ansin the same phase as the reactants what are standard conditions for heterogenous catalysts - ansHeterogeneous catalysts are usually solids whereas the reactants are gaseous or in solution. The reaction occurs at the surface of the catalyst. how do heterogenous catalysts work - ansAdsorption of reactants at active sites on the surface may lead to catalytic action. The active site is the place where the reactants adsorb on to the surface of the catalyst. This can result in the bonds within the reactant moleculesbecomingweaker,or themoleculesbeingheldin a more reactive configuration. There will also be a higher concentration of reactants at the solid surface so leading to a higher collision frequency. how does the strength of adsorption help to determine the effectiveness of the catalytic activity. - ansSome metals e.g. W have too strong adsorption and so the products cannot be released. Some metals e.g. Ag have too weak adsorption, and the reactants do not adsorb in high enough concentration. what is the effect of increasing surface area - ansIncreasing the surface area of a solid catalyst will improve its effectiveness. A support medium is often used to maximise the surface area and minimise the cost (e.g. Rh on a ceramic support in catalytic converters). contact process equation (manufacture of sulphuric acid) - ansV2O5 is used as a catalyst in the Contact Process. Overall equation : 2SO2 + O2 --> 2SO3 step1 SO2 +V2O5 --> SO3 + V2O step 2 2V2O4 + O2 --> 2V2O what are the effects of catalytic poisoning - ansPoisoning has a cost implication e.g. poisoning by sulphur in the Haber Process and by lead in catalytic converters in cars means that catalysts lose their efficiency and may need to be replaced.
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
what happens with M3+ ions with carbonates - ansThe 3+ ions with carbonate solution form a M(OH)3 ppt and CO2 gas is evolved why is a carbonate salt not formed with metal 3+ ions - ansMCO3 is formed with 2+ ions but M2(CO3)3 is not formed with 3+ ions. The difference is explained by the greater polarising power of the 3+ ion due to its higher charge density. precipitates formed in the carbonate (acidity reactions) - ansAl forms white ppt of Al(OH) (H2O)3 + CO2 Fe(III) forms brown ppt of Fe(OH)3 (H2O)3 + CO What is the relative mass and charge on a proton? - ansMass 1 charge + What is the relative mass and charge on a neutron? - ansMass 1 Charge 0 What is the relative mass and charge on an electron? - ansMass 1/ Charge - 1 What is the mass number? - ansThe total number of protons and neutrons in the nucleus of an atom What is the Atomic (proton) number? - ansThis is the number of protons in the nucleus of an atom and is used to identify an element What are Ions? - ansIon have different numbers of protons and electrons. Negative ions have more electrons than protons and positive ions have fewer electrons than protons. What are isotopes? - ansIsotopes of an element are atoms with the same number of protons but different numbers of neutrons describe Thomson's model of the atom. - ansThomson's model of the atom was like a 'plum pudding' with a positively charged pudding (solid sphere) that contained negatively charged particles (electrons). What was found in Rutherford's gold foil experiment? - ansWhen alpha particles were fired at a thin gold sheet, most of them passed straight through with a very small number deflected straight back. What was Rutherford's new nuclear model for the atom? - ansA tiny positively charged nucleus at the centre, surrounded by a cloud of negative electrons. Most of the atom is empty space. What did Bohr's atom model show? - ansElectrons only exist in fixed orbits and not anywhere in between. Each Shell has a fixed energy. When an electron moves between shells, electromagnetic radiation is emitted or absorbed. Because the energy of the shells is fixed, the radiation will have a fixed energy. What difference is found between the original Bohr atom model and the refined Bohr model?
- ansScientists discovered that not all electrons in a shell have the same energy, so it was refined to include sub shell's. What is relative atomic mass? - ansThe average mass of an atom of an element compared to one twelfth of the mass of an atom of carbon 12. What is relative isotopic mass? - ansRelative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of Carbon-12 is exactly 12.
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
Calculating relative atomic mass - ansrelative atomic mass = isotopic masses x percentages/total percentage What is relative molecular mass? - ansThe average mass of an entity compared to one twelfth of the mass of an atom of carbon 12. What is the equation used to calculate the number of moles of any substance? - ansNumber of moles = mass(g)/ mass of one mole (mol) What are the 5 stages in mass spectrometery? - ansvaporisation, ionisation, acceleration, deflection, and detection What happens during the vaporisation stage of mass spectrometry? - ansThe sample is turned into a gas using an electrical heater in a vacuum. What happens during the ionisation stage of mass spectrometry? - ansAn electron gun fires a beam of high energy electrons which bombards the gaseous particles, knocking off electrons leaving a positive ion What happens during the acceleration stage of mass spectrometry? - ansThe positive ions are attracted by negatively charged plates in an electric field which accelerates the ions and focuses the beam. What happens during the deflection stage of mass spectrometry? - ansThe fast moving ions pas into a string magnetic field, deflecting the ions into a curved path. The degree of deflection depends on the Mass/charge ratio (m/z). Ions with with a high m/z ratio are deflected the least (they're heavier). The strength of the magnet is gradually increased so that ions with different m/z ratios are deflected towards the detector. What happens during the detection stage of mass spectrometry? - ansThe positive ions hit an electrically charged plate/ the current produced is then amplified and recorded as a 'peak'. Each peak is a measure of the relative abundance of each ion. What is the general ionisation equation? - ansX(g) => X+ = e- What does a mass spectrum chart show? - ansEach line represents a different isotope of an element. the height of each peak gives the relative isotopic abundance (the amount of it). For a molecular substance the peak with the greatest m/z ratio corresponds to the Mr. What are the steps in calculating relative atomic mass? - ansStep 1: For each peak multiply the relative isotopic abundance by the relative isotopic mass. Step 2: Add up these totals. Step 3: Divide by 100 How many orbitals do each-sub shell contain? - anss - 1 p - 3 d - 5 f - 7 What are four rules for electronic arrangement notation? - ans1: Each principle and subsidiary level fills up before the next one 2: When the 3p energy level is full, the 4s level fills before the 3d 3: When an atom or ion has 3d electrons, the 4s is written after the 3d 4: Atoms that have 3d electrons always lose the 4s electrons first while forming ions
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
What is percentage yield and what is its formula? - ansFor any reaction the actual mass of the product (actual yield) will be less than the theoretical yield. percentage yield = actual yield / theoretical yield x 100 What is Atom economy? - ansAtom economy is a measure of the proportion of reactant atoms that become part of the desired product (rather than by-products) in the balanced chemical equation. What is the formula for Atom economy? - ans% atom economy = mass of desired product / total mass of reactants x 100 What is electrostatic attraction? - ansElectrostatic attraction holds positive and negative ions together - it is very strong. What is ionic bonding? - ansIonic bonding is bonds that have electrostatic attraction. When oppositely charged ions form an ionic bond you get an ionic compound. What are giant ionic lattices? - ansA lattice is just a regular structure. Ionic crystals are giant lattices of ions. Different ionic compounds have different shaped structures but they're all still giant lattices. What is the electrical conductivity of an ionic compound? - ansIonic compounds conduct electricity when they're molten or dissolved - but not when they're solid. The ions in a liquid are free to move and carry a charge. In a solid they're in a fixed position by the strong ionic bonds. What is the melting point for ionic compounds? - ansIonic compounds have high melting points. The giant ionic lattices are held together by strong electrostatic forces. It takes lots of energy to overcome these forces, so melting points are very high. What is the solubility of ionic compounds? - ansIonic compounds tend to dissolve in water. Water molecules are polar - part of the molecule has a small negative charge and the other bits have small positive charges. The water molecules pull the ions away from the lattice and cause it to dissolve. What is a covalent bond? - ansIn covalent bonding, two atoms share electrons, so they've both got full outer shells of electrons. Both the positive nuclei are attracted electrostatically to the shared electrons. What is the electrical conductivity like in a covalent bond? - ansSimple covalent compounds don't conduct electricity because there are no free ions to carry the charge. What is the melting point of a covalent bond? - ansSimple covalent bonds have low melting points because the weak forces between molecules are easily broken. What is the solubility of the covalent bonds like? - ansSome simple covalent compounds dissolve in water depending on how polarised the molecules are What are giant covalent structures - ansGiant covalent structures have huge networks of covalently bonded atoms. Carbon often forms this type of structure because they can each form four strong covalent bonds. What are the properties in Graphite? - ansGraphite has carbon atoms arranged in sheets of flat hexagons bonded with three bonds each. The fourth outer electron of each carbon is delocalised. The sheets of hexagons are bonded together by Van der Waals forces. Graphites weak bonds means that the layers can easily slide over one another, used in pencils and lubricants.
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
It can also conduct electricity due to its delocalised electrons that are free to move along the sheets. It has a very high melting point due to the strong covalent bonds in the hexagon sheets. It is also insoluble. What are the properties of Diamond? - ansDiamonds carbon atoms are boned to four other carbon atoms. These are arranged in a tetrahedral shape. Diamond has a very high melting point and is very hard, it cannot conduct electricity due to all of its electrons being held in localised bonds. it can also not dissolve in a solvent. What is a dative covalent bond? - ansIn dative covalent, also known as co-ordinate bonding, one atom proved both of the shared electron in the bond. What is a lone pair? - ansAn unshared electron pair in a covalent bond. What is a charge cloud? - ansBonding pairs and lone pairs of electrons exist as charge clouds. A charge cloud is an area where you have a really big chance of finding an electron pair. What is electron pair repulsion theory? - ansElectrons are all negatively charged, so the charge clouds will repel each other as much as they can. The shape of the cloud charge affects how much it repels other charges. Lone pair charge clouds repel more than bonding- pair charge clouds. What is electronegativity? - ansThe ability to attract the bonding electrons in a covalent bond. It is meausred on the Pauling scale. The higher the number the better the ability to attract the bonding electrons. What is a dipole? - ansWhen there is a large difference in electronegativity in a polar bond so there is a large difference in charge between the two atoms caused by a shift in electron density in the bond. What are Van der Waals forces? - ansVan der Waals forces cause all atoms and molecules to be attracted to one another. They're caused by temporary dipoles which occur when the moving electrons within a charge cloud are more to one side than the other. Larger molecules or molecules with a greater surface area have more Van der Waals forces. What are permanent dipole-dipole forces? - ansthese are the weak electrostatic forces that occur between polar molecules. What is hydrogen bonding? - ansHydrogen bonding is the strongest intermolecular force. it only happens when hydrogen is covalently bonded to fluorine, nitrogen or oxygen because they're very electronegative and can pull the bonding electrons away from the hydrogen. Substances with hydrogen bonding have higher melting and boiling points because of the extra energy needed to break the hydrogen bonds. What is metallic bonding? - ansMetal elements exist as giant metallic lattice structures. The outermost shell of electrons of a metal atom is delocalised, leaving a positive metal ion. The positive metal ions are attracted to the delocalised negative electrons. How does metallic bonding explain the melting points of metals? - ansThe number of delocalised electrons per atom affects the melting point. The more there are, the stronger the bonding will be and the higher the melting point. The size of the metal ion and the lattice structure also affect the melting point. How does metallic bonding explain metals ability to be shaped? - ansAs there are no bonds holding specific ions together, the metal ions can slide over one another when the structure is pulled, so metals are malleable and ductile (can be pulled into a wire)
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
What is thermal cracking? - ansThermal cracking takes place as a high temperature of up to 1000'C and high pressures of up to 70 atm. It produces a lot of alkenes which are used to make valuable products like polymers. What is catalytic cracking? - ansCatalytic cracking makes mostly motor fuels and aromatic hydrocarbons. It uses a zeolite catalyst at a slight pressure and a high temperature of 450'C. Using a catalyst cuts costs because a lower temperature and pressure can be used. It also speeds up the rate of reaction. What is complete combustion? - ansIf you burn (oxidise) alkanes with plenty of oxygen, you get carbon dioxide and water What is incomplete combustion? - ansIf there's not enough oxygen, hydrocarbons cannot combust incompletely and you get a particulate carbon soot and carbon monoxide gas as well as carbon dioxide. This is bad because carbon monoxide gas is poisonous. What are unburnt hydrocarbons. - ansThese are emitted when engines don't burn all of the fuel molecules. These hydrocarbons react with nitrogen oxides in the presence of sunlight to form ground level ozone (O3) which is a major component of smog What is a catalytic converter? - ansCatalytic converters can help remove the three main pollutants from vehicle exhausts (nitrogen oxides, unburnt hydrocarbons and carbon monoxide) using transition metals such as rhodium and platinum which convert them into less harmful chemicals. Hess's Law - ansThe Enthalpy Change for a chemical reaction is independent of the route taken Bond Dissociation Enthalpy - ansThe Enthalpy Change needed to break 1 mole of a covalent bond with all species in the gaseous state The energy given out is the same as the amount taken in when the bond is formed always endothermic, ∆H is positive ∆H = ∑(Bonds Broken) - ∑(Bonds Formed) Mean Bond Enthalpy - ansThe Enthalpy Change needed to break a bond, averaged over different molecules Why aren't mean bond enthalpy values very accurate? - ansthey are averaged over a range of compounds How would a value for ∆Hc, differ if it was measured with a reactant in the gaseous state compared to a reactant in the liquid state - ansmore exothermic and negative, as heat is released when water vapour condenses, so less heat is needed to vapourise water. also molecules have more energy in the gaseous state. Standard Molar Enthalpy of Formation - ansThe Enthalpy Change when 1 mole of a substance is formed from it's constituent elements under standard conditions. With all reactants and products in their standard states ∆Hc = ∑∆Hf(Products) - ∑∆Hf(Reactants)
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
Standard Molar Enthalpy of Combustion - ansThe Enthalpy Change when 1 mole of a substance is completely burned in excess oxygen under standard conditions with all reactants and products in their standard states. ∆Hc = ∑∆Hc(Reactants) - ∑∆Hc(Products) Heat - ansThe total energy of all particles present in a given substance. Heat is dependent on the amount of substance Temperature - ansRelated to average Kinetic Energy of particles in a system, particles move faster and Kinetic Energy increases so temperature goes up. Temperature is independent of amount of substance. Equation for Measuring ∆H of a reaction - ansq = mc∆T ∆H = q/mol m = g or cm c = Jg-K-, is the specific heat capacity, the amount of heat needed to raise the temperature of 1g of a substance by 1 K q= J Calorimeter: Errors in method - ansHeat loss, Incomplete fuel combustion, incomplete heat transfer, evapouration of fuel after weighing, measurements are sometimes not under standard conditions, heat capacity of calorimeter isn't included Ways of minimising heat loss in a calorimeter - ansUsing a draught screen, mineral wool, lid, enclosing the flame, burning in pure oxygen not air. and using a bomb calorimeter, which is the most accurate piece of apparatus, so it is used to find data book values Why is it important to know how much energy is involved during a reaction? - ansCan measure fuel energy values, can calculate energy requirements for industry, can find theoretical energy amounts for bond making and bond breaking, can predict if a reaction will take place or not Exothermic Reactions - ansEnergy's transferred from the system to the surroundings. The energy needed to break bonds is less than the energy released when bonds are formed. Products have less energy than reactants ∆H = negative (as energy is lost from the system) Examples of exothermic reactions - ansNeutralisation, Fuel Combustion, Carbohydrate Oxidation (used in respiration) Endothermic Reactions - ansEnergy is taken up from the surroundings to the system, energy is needed to break bonds more than is released when the bonds are formed, so energy input is required to proceed. Products have more energy than reactants ∆H = positive (as energy is added to the system) Examples of Endothermic Reactions - ansThermal Decomposition e.g. CaCO3 → CaO + CO Rate of Reaction - ansThe change in concentration of either reactants or products per unit time
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
lower charge density First Ionisation Energy down Group 2 Alkali Metals - ansDecreases down the group, Outer electrons are held successively further from the nucleus outer electrons are more shielded from the positive nucleus Reactions of group 2 with oxygen - ansgroup 2 metals burn in oxygen Magnesium + Oxygen - ansburns with a white flame to produce a white solid with high melting point (ionic). Magnesium also reacts slowly with oxygen even without the flame, so a thin layer of MgO is always on Mg ribbon and needs to be cleaned off by emery paper Measuring the rate of reaction of magnesium - ansif not cleaned properly both Mg and MgO will react with acid at different rates. Mg + 2HCL →MgCL2 + H MgO + 2HCL → MgCl2 + H2O Group 2 Metals + Water - ansVigour increases down group 2 hydroxides are produced X + 2H2O (l) → X(OH)2(aq) + H2(g) fizzing and effervescence increases down the group solution heats up more down the group (move exothermic) metal dissolves faster down the group so the amount of white precipitate reduces down the group Magnesium + Water - ansMagnesium burns in steam to produce MgO and H white flame Mg(s) + H2O(g) → MgO(s) + H2(g) Magnesium reacts with warm water to produce Mg(OH)2 and H Mg(s) + 2H2O(l) → Mg(OH)2 + H slower, no flame Solubility of Mg(OH)2 - ansMg(OH)2 is insoluble in water Mg2+ + 2OH- → Mg(OH)2 (simplest ionic equation) Mg(OH)2 suspension in water, will be slightly alkaline, pH so some hydroxide ions have been produced by dissociation Use of Mg(OH)2 - ansTo treat constipation and neutralise excess stomach acid safe as it is weakly alkaline Solubility + Use of Ca(OH)2 - ansCa(OH)2 is quite soluble in water used to neutralise acidic salts Ca(OH)2 = limewater
- test for CO
- Ca(OH)2 + CO2 → CaCO3 + H2O
- limewater turns cloudy Solubility + Use of Ba(OH)2 - ansBa(OH)2 is very soluble in water hydroxide ions are produced so the solution is very alkaline as a result of Ba(OH)2 dissolving
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
Ba(OH)2 + aq → Ba2+ + 2OH- Group 2 Sulphates - ansSolubility decreases down the group ppt formation equations are: XCl2 + Na2SO4 → 2NaCl + XSO4(s) or X2+ + SO4 2- → XSO4(s) BaSO4 - ansleast soluble barium meal given to patients to absorb x rys reacts with sulphuric acid
- slow reaction BaSO4 covers metal and prevents further reduction Ba + H2SO4 →BaSO Sulphate Test
- unknown compound + BaCl2 + HCl
- white precipitate of BaSO4 ( Ba2+ + SO4 2- →BaSO4(s) ) whiy is HCl is used in the sulphate test - ansto remove carbonate ions impurities from sulphate ion salts as they would react with BaCl2 to give BaCO3 which is an incorrect result HCl + Na2CO3 →2NaCl + H2O + CO
- fizzing
- carbonate ions are removed Ore - ansRocks with a high enough percentage of a metal to be extracted commercially What are the main forms an ore takes - ansan oxide or a sulphide What metals can be extracted using Carbon - ansIron (Fe2O3), Manganese (MnO2) and Copper (CuCO3) Advantages of using Carbon for extraction - ansCheap and effective, Readily available Disadvantages of using Carbon for extraction - ansHigh temperatures, metal carbides formed sometimes What metal is exacted using hydrogen? - anstungsten: WO Temp > Advantages of using Hydrogen for extraction - ansNo pollution, readily available, better purity than C (no carbides are formed) Disadvantages of using Hydrogen for extraction - ansExplosive, difficult to store, expensivee What metal is exacted using an active metal? - ansTitanium (TiO2) Temperature: 1st Stage ~ 2nd stage ~ Why is TiO2 converted to TiCl4 before extraction? - ansTiCl4 is molecular (TiO2 is ionic), so it can be purified by fractional distillation (liquid at rt) Why is Titanium a useful metal? - ansAbundant, low density, corrosion resistant, strong, light alloys
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
I- → Brown solution, black solid Identification of halide ions - ansAgNO3 and HNO
- HNO3 removes any CO3 2- impurities which would precipitate and mask results
- observe colour of ppt
- dissolve in dil/conc. NH Reducing Strength of Halide ions - ansIncreases down the group - more easily oxidised, Identification of Halide + H2SO4 products - ansHX → white steamy fumes Br2 → red fumes SO2 → colourless acidic gas H2S → bad eggy smell S → yellow solid I2 → purple fumes/black solid Disproportionation of Chlorine + Water - ansHClO and HCl are produced, universal indicator is red then bleached white Disproportionation of Halogen + Sodium Hydroxide - ansNaX, NaXO, H2O are produced, mixture is used to bleach and kill bacteria (disinfectant) Chlorine + Water in Sunlight - ansH+, Cl- and O2 are produced, green Cl2 fades as it reacts to form O2 (colourless) Cl2 uses - ansto kill bacteria, health benefits outweigh toxicity Industrial Alkene Hydration to form alcohols - ansWater +conc. H3PO4 catalyst, 1 step reaction, no waste products (high atom economy), high temperatures and pressures 300 - 600 degrees and 70 atm Seperation of products is easier and cheaper Use of poly(ethene) - ansPlastic Bags, buckets, bottles, its flexible, easily moulded, low density, water and chemical proof Use of poly(propene) - ansUtensils, Containers, Rope, Carpet Fibre, Stiff Why are polyalkenes unreactive? - ansdue to strong C-C and C-H bonds Distillation - ansTechnique that separates organic product from reacting mixture
- used for the oxidation of primary alcohols to aldehydes Reflux - ansHeatly reaction mixture for long periods, organic vapours are condensed to liquids so they don't escape, condenser isn't sealed to prevent pressure build up and explosion
- used for oxidation of aldehydes and secondary alcohols Alcohol + dehydrating agent - ansAlkenes are produced, conc. H2SO4/ H3PO4 is used, warm under reflux, acid catalysed elimination Using Ethene to produce ethanol - ansHigh temperatures and pressures are required, conc. H3PO4 catalyst is needed, Advantages of using Ethene to produce ethanol - ansfaster, purer, continuous (cheaper) Disadvantages of using Ethene to produce ethanol - anshigh tech equipment needed, non- renewable, high energy costs to high pressure Fermentation of Glucose to produce ethanol - ansglucose 2 ethanol + 2 carbon dioxide Conditions for the fermentation of Glucose - ansyeast anaerobic conditions
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
- air would cause ethanol to be oxidised to produce ethanoic acid 30 - 40 degrees (optimum of 38)
- if too low slow reaction, if too high, enzyme denaturation Advantages of fermentation of Glucose to produce ethanol - ansSugar is renewable, low technology level = cheap equipment Disadvantages of fermentation of Glucose to produce ethanol - ansSlow batch process, stopping and starting high production costs ethanol needs to be purified using fractional distillation depletes land used for growing food crops Carbon Neutrality of Ethanol - ansNo net CO2 emissions into the atmosphere, due to photosynthesis of sugar crops which are used to produce glucose for fermentation Disdvantages of Recycling Metals - ansCollecting, Sorting and Transporting costs Give one reason why a reaction is very slow at room temperature - ansHigh Ea so few molecules have E>Ea, and low rate of successful collisions Explain why an increase in pressure at constant temperature increases the rate of reaction - ansMore particles in a given volume so increased frequency of collisions Give an example of a reagent which could be used to show that the reducing agility of bromide ions is different from that of chloride ions - ansconc. H2SO Write an equation for the reaction between chlorine and cold, dilute aqueous sodium hydroxide. Give two uses of the resulting solution - ansCl2 + NaOH → NaClO + NaCl + H2O, bleach, disinfectant State the source of the energy for the extraction of iron in a blast furnace - ansThe combustion of coke, air is blown in C + O2 → CO CO2 + C → 2CO Molecular Formula - ansThe actual number of atoms of each element in a molecule Transition Metal - ansAn Element that has an incomplete d sub-shell in either its atoms or one or more of its ions Why is Zn not a transition metal? - ansZn can only form a +2 ion. In this ion the Zn2+ has a complete d orbital and so does not meet the criteria of having an incomplete d orbital in one of its compounds. Properties of Transition Metals - ans1) Variable oxidation states
- Catalytic action
- Coloured compounds
- Formation of complexes Ligand - ansAtom/Ion with a lone pair that forms co-ordinate bonds to metal. Complex - ansMetal ion with ligands co-ordinately bonded to it. Co-Ordination Number - ansNumber of co-ordinate bonds from ligands to metal ions Lewis Base - ansLone pair donor Lewis Acid - ansLone Pair Acceptor
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
Substance made when [Cr(H2O)6]3+ reacts with XS NaOH (Formula, colour, state) - ans[Cr(OH)6]3- Green, Soln, Substance made when [Cr(H2O)6]3+ reacts with dil. NH (Formula, colour, state) - ans[Cr(H2O)3(OH)3] Grey-Green, Ppt, Substance made when [Cr(H2O)6]3+ reacts with XS NH (Formula, colour, state) - ans[Cr(NH3)6]3+ Purple, Soln, Substance made when [Cr(H2O)6]3+ reacts with sodium carbonate. (Formula, colour, state) - ans[Cr(H2O)3(OH)3] Grey Green Ppt CO2 - effervescence Possible main products when [Cr(H2O)6]3+ reacts with Zn or conc HCl. State the type of reaction and colours. - ans1) [Cr(H2O)6]2+ (aq) reduction, blue soln.
- Cr2O7 (aq) reduction, orange soln. Products when [Cr(OH)6]3- reacts with hydrogen peroxide. - ans2CrO4^2- +2OH- + 8H2O Products when [Cr(OH)6]3- reacts with sodium hydroxide. - ansCrO4^2- + 3e- + 4H2O Reagents required to form CrO4^2- - ansNaOH or H2O Colour of Fe3+ metal aqua ion in soln - ansBrown pH of Fe3+ metal aqua ion in soln - ans3/ Substance made when [Fe(H2O)6]3+ reacts with dil. sodium hydroxide - ans[Fe(H2O)3(OH)3] Brown ppt Substance made when [Fe(H2O)6]3+ reacts with sodium hydroxide in excess. - ansNo Change Substance made when [Fe(H2O)6]3+ reacts with dil ammonia - ans[Fe(H2O)3(OH)3] Brown ppt Colour of Fe2+ metal aqua ion in soln - ansGreen pH of Fe2+ metal aqua ion in soln - ans5/ Colour of Co2+ metal aqua ion in soln - ansPink Substance made when [Fe(H2O)6]2+ reacts with dil sodium hydroxide - ans[Fe(H20)4(OH)2] Green Ppt Substance made when [Fe(H2O)6]2+ reacts with dil ammonia - ans[Fe(H20)4(OH)2] Green
Comprehensive Exam Study Guide 2025
100% Certified by an Expert
Ppt Substance made when [Fe(H2O)6]2+ reacts with ammonia in excess - ans[Fe(H20)3(OH)3] brown ppt due to oxidation Substance made when [Fe(H2O)6]2+ reacts with sodium carbonate - ansFeCO Green Ppt Formula of Co2+ metal aqua ion - ans[Co(H2O)6]2+ Substance made when [Co(H2O)6]2+ reacts with dil. NaOH - ans[Co(H2O)4(OH)2] Blue Ppt Substance made when [Co(H2O)6]2+ reacts with XS NaOH - ansNo Change from dilute Substance made when [Co(H2O)6]2+ reacts with dil. NH3 - ans[Co(H2O)4(OH)2] Blue Ppt Substance made when [Co(H2O)6]2+ reacts with XS NH3 - ansPale Brown Sol [Co(NH3)6]2+ Substance made when [Co(H2O)6]2+ reacts with conc. HCl - ansBlue Soln [CoCl4]2- Substance made when [Co(H2O)6]2+ reacts with sodium carbonate - ansLilac ppt CoCO Product when [Co(NH3)6]2+ is left to stand in air. - ans[Co(NH3)6]3+ Dark Brown Soln Formula of Cu2+ metal aqua ion in solution - ans[Cu(H2O)6]2+ Colour of Cu2+ metal aqua ion in solution - ansBlue pH of Cu2+ metal aqua ion in soln - anspH 5/ Substance made when [Cu(H20)6]2+ reacts with dil. Sodium Hydroxide. - ans[Cu(H20)4(OH)2] blue ppt Substance made when [Cu(H20)6]2+ reacts with dil. Ammonia. - ans[Cu(H20)4(OH)2] blue ppt Substance made when [Cu(H20)6]2+ reacts with conc. Ammonia. - ansblue ppt redissolves [Cu(NH3)4(H20)2]2+ Substance made when [Cu(H20)6]2+ reacts with conc. HCl - ans[CuCl4]2- Green Soln
