Alevel Revision

Question 1

• What is mass/ atomic number?
• What are isotopes ?
• Explain the The principles of a simple time of flight (TOF) mass spectrometer, limited to ionisation, acceleration to give all ions constant kinetic energy, ion drift, ion detection, data analysis?
• What is the purpose of mass spectrometry ?
• How do you interpret simple mass spectra of elements And calculate relative atomic mass from isotopic abundance, limited to mononuclear ions?

Question 2

Explain the electron configurations including all the sun shells
define first ionisation energy
write equations for first and successive ionisation energies
explain how first and successive ionisation energies in Period 3 (Na–Ar) and in Group 2 (Be–Ba) give evidence for electron configuration in sub-shells and in shells.

Question 3

What is ar and mr

Question 4

Explain the Avogadro constant
Equation for amount in moles
How to find concentration, volume and amount of substance in a solution.

Question 5

What is ideal gas equation

Question 6

What is empirical and molecular formulas what is the relation
How to calculate empirical formula from data giving composition by mass or percentage by mass
How to calculate molecular formula from the empirical formula and relative molecular mass.

Question 7

How to write a full or ionic equation
What is atom economy
What are the Economic, ethical and environmental advantages for society and for industry of developing chemical processes with a high atom economy. write balanced equations for reactions studied
How to balance equations for unfamiliar reactions
when reactants and products are specified.
Students should be able to use balanced equations to calculate:
masses
volumes of gases
percentage yields
percentage atom economies
concentrations and volumes for reactions in solutions.

Question 8

What is an ionic bond
How are compound ions formed give examples
How to predict the charge on a simple ion using the position of the element in the Periodic Table
How to construct formulas for ionic compound

Question 9

What is a covalent and vo ordinate bond
What is metallic bonding

Question 10

What are the four types of crystal structures give examples

relate the melting point and conductivity of materials to the type of structure and the bonding present
explain the energy changes associated with changes of state
draw diagrams to represent these structures involving specified numbers of particles.

Question 11

What are bonding pair and lone pair of electrons what causes repulsion
What are the The effect of electron pair repulsion on bond angles

explain the shapes of, and bond angles in, simple molecules and ions with up to six electron pairs (including lone pairs of electrons) surrounding the central atom.

Question 12

What is electronegative
What is a polar covalent bond and a permanent dipole

How do you use partial charges to show that a bond is polar
explain why some molecules with polar bonds do not have a permanent dipole.

Question 13

What are the 3 different intermolecular forces how does the melting an boiling point differ
What is the importance of hydrogen bonding in the low density of ice and the anomalous boiling points of compounds.

explain the existence of these forces between familiar and unfamiliar molecules
explain how melting and boiling points are influenced by these intermolecular forces.

Question 14

What is the definition for enthalpy?
* What is the unites for change in enthalpy?
* What happens during bond braking and forming and what type of reaction is it?
* What is the equation for enthalpy change?

Answer 14

• Enthalpy is the heat energy change measured under constant pressure
• kj mol -1

Question 15

• What is the definition for hess law
• Describe how to do hess law for enthalpy of formation
• Describe how to do hess law for enthalpy of combustion

Answer 15

• The enthalpy change is independent to the rout it takes
• In a question the enthalpy of formation for compounds are given, the second equation that you write at the bottom is the elements the product is formed from.
  write in the given enthalpies and reverse the pos or neg from the second equation to the products side as all the arrows will be pointing toward the smaller equation containing the constituent elements

Question 16

• Describe how to do hess law for enthalpy of formation
• Describe the Hess law for combustion

Answer 16

• In a question n enthalpy of formation for compounds are given, the second equation that you write at the bottom is the elements the product is formed from.
  write in the given enthalpies and reverse the pos or neg from the second equation to the products side as all the arrows will be pointing toward the smaller equation containing the constituent elements
• when doing combustion reaction the smaller equation at the bottom is going to be co2 and h2o you will have to see the number of carbon and hydrogen in the equation to find the number of co2 and h20 and all the arrows go to the small equation containing h2o and co2

Question 17

• Define mean bond enthalpy?
• What is the difference between mean bond enthalpy and enthalpy in hess law?

Answer 17

• average energy needed to break a bond in a compound
• Mean bond enthalpies are mean values calculated across a range of compounds containing that bond where as Hess’s law find the actual values of the bond enthalpies in that reaction

Question 18

define the term activation energy
explain why most collisions do not lead to a reaction.

Question 19

Explain Maxwell–Boltzmann distribution of molecular energies in gases.

draw and interpret distribution curves for different temperatures.

Question 20

What is rate of reaction.

What are the qualitative effect of temperature changes on the rate of reaction.

use the Maxwell–Boltzmann distribution to explain why a small temperature increase can lead to a large increase in rate. Required practical 3
Investigation of how the rate of a reaction changes with temperature.

Question 21

What arrr we the qualitative effect of changes in concentration on collision frequency.

What is the The qualitative effect of a change in the pressure of a gas on collision frequency.
explain how a change in concentration or a change in pressure influences the rate of a reaction.

Question 22

What is a catalyst

use a Maxwell–Boltzmann distribution to help explain how a catalyst increases the rate of a reaction involving a gas.

Question 23

What happens to the concentration and rate In a reversible reaction at equilibrium
What is le chatalias principle what is used for
Does catalysts affect position of equilibrium

use Le Chatelier’s principle to predict qualitatively the effect of changes in temperature, pressure and concentration on the position of equilibrium
explain why, for a reversible reaction used in an industrial process, a compromise temperature and pressure may be used.

Question 24

What is an equilibrium constant equation deduced from and for
Dose concentration of catalyst affectequlibrij
Constant

construct an expression for Kc for a homogeneous system in equilibrium
calculate a value for Kc from the equilibrium concentrations for a homogeneous system at constant temperature
perform calculations involving Kc
predict the qualitative effects of changes of temperature on the value of Kc

Question 25

What is oxidation and reduction What are the rules of assigning oxidation states work out the oxidation state of an element in a compound or ion from the formula write half-equations identifying the oxidation and reduction processes in redox reactions combine half-equations to give an overall redox equation.

Question 26

Define lattice enthalpy formation and dissociation?

Answer 26

* Formation is the enthalpy change when one mole of solid ionic compound is formed from its gasious ions * dissociation it is dissociated insead of formed

Question 27

What in a born hanger cycle is used to find lattice enthalpy?

Answer 27

* enthalpy of formation * ionisation enegry * enthalpy of atomisation * bond enthalpy * electron affinity

Question 28

Define enthalpy of formation Define ionisation energy? Define enthalpy of atomisation? Define bond enthalpy? Define electron affinity?

Answer 28

* Enthalpy change when one mole of compound is formed from its elements in their standeard state under standard conditions * Enthalpy change when one mole of gaseous ions 1+ ions is formed from 1 mole of gaseous atoms * Enthalpy change when 1 mole of compound is converted to gaseous ions atoms * Enthalpy change when all bonds of the same type in one mole of gaseous molucles are broken * Enthalpy cahnge when 1 mole of gaseous 1- ions is formed from 1 mole of geaseous atoms

Question 29

How do you construct a born barber cycle to find lattice enthalpy?

Answer 29

Llattice enthalpy=first electron affinity - first ionisation energy-atomistion enthalpy + enthalpy of formation take eveythin away exept formation as the arrow on the cycle gose the other way

Question 30

How can we use lattice enthalpy from experimental values and theoretical value to see if their more ionic or if they have covalent character?

Answer 30

If experemntal value is further away from the theoretical vale, it will have more covalent charcteristics as it is more polorised, this means that it will be stronger than the predicted ionic model

Question 31

* Define enthalpy change of hydration? * Define enthalpy change of solution?

Answer 31

* Enthalpy change when 1 mole of aqueous ions is formed from 1 mole of gaseous ions * Enthalpy change when 1 mole of solute is dissolved in enough solution that further enthalpy change would not happen

Question 32

How to draw a born harper cycle using enthalpy of solution, hydration and lattice dissociation enthalpy

Answer 32

lattice dissociation enthalpy add enthalpy of hydration, you will be asked to draw a born harber cycle (look up)

Question 33

Define entropy? What affects entropy? What is ment by feasible? How to find total entropy? how to entropy of vapourisation?

Answer 33

* The level of disorder * The state and number of particles * reactions tend towards disoreder so some reaction are just feasible (just happen) * total S= S of products -S of reactants * Rearranging the Gibbs equation allows us to find the entropy change using the enthalpy change: ΔGꝋ = ΔHꝋ – TΔSꝋ = 0 ΔHꝋ = TΔSꝋ ΔSꝋ = ΔHꝋ / T (google the rest)

Question 34

* Define gibs free energy change * What is the equation for gibs free energy give unites and what should it equal to for the reaction to be feasible

Answer 34

* it preicts if a reaction is feasible or not * if it it is less that or equall to 0 the reaction may happen, the equation is ∆G = ∆H – T∆S (enthalpy (j mol-1)- temperature(k) * entropy(J K-1 mol-1))

Question 35

* How gibs free energy is affected by a change in temperature * If a reaction is feasible how can you calculate temperature?

Answer 35

* exothermic (-∆H) and postive entropy(+∆S)= reaction is feasible at any temperatures * endothermic (+∆H) and negtive entropy(-∆S)= reaction is not feasible at any temperatures * endothermic (+∆H) and postive entropy(+∆S)= reaction will only be feasible at high temperatures * exothermic (-∆H) and negtive entropy(-∆S)= reaction is feasible at low temperatures * if a reaction is feasible rearrange to make T subject ΔGꝋ = ΔHꝋ – TΔSꝋ = 0 ΔHꝋ = TΔSꝋ ΔSꝋ = ΔHꝋ / T

Question 36

What is a rate equation describe and explain rate constants and orders What is the equation for rate constants and what may cause it to vary define the terms order of reaction and rate constant perform calculations using the rate equation explain the qualitative effect of changes in temperature on the rate constant k perform calculations using the equation k = Ae–Ea/RT understand that the equation k = Ae–Ea/RT can be rearranged into the form ln k = –Ea /RT + ln A and know how to use this rearranged equation with experimental data to plot a straight line graph with slope –Ea/R How can orders with respect to reactants can provide information about the mechanism of a reaction. use concentration–time graphs to deduce the rate of a reaction use initial concentration–time data to deduce the initial rate of a reaction use rate–concentration data or graphs to deduce the order (0, 1 or 2) with respect to a reactant derive the rate equation for a reaction from the orders with respect to each of the reactants use the orders with respect to reactants to provide information about the rate determining/limiting step of a reaction.

Question 37

What is the The equilibrium constant Kp how is it calculated derive partial pressure from mole fraction and total pressure construct an expression for Kp for a homogeneous system in equilibrium perform calculations involving Kp predict the qualitative effects of changes in temperature and pressure on the position of equilibrium predict the qualitative effects of changes in temperature on the value of Kp understand that, whilst a catalyst can affect the rate of attainment of an equilibrium, it does not affect the value of the equilibrium constant

Question 38

what is the relation of partal pressure to total pressure what is mole reaction equation for partial pressure equilibrium constant what affect kp

Answer 38

partial pressire a+B+C=total pressure no of moles of gas / total no of moles molfraction times total prssure product/raectants temperature -if equilibrum moves to the right kp incraeses ( increase temp means lachetalia principle moves to the endothermic side vise versa if equilibrim moves to the left kp reduces pressure unaffect by pressure catlysists sppeds up raection

Question 39

what is a half cell what is electrochemical cells what are the compounds what happens how to know what way a rection is going from emf vale what dose a more negative and positive emf value tell us about what's happened what is a standard hydrogen electrode and why pt is used what is the purpose of salt bridge give an example what is equation for emf how to formulate electrochemical cell what are the standard conditions what dose emf value tell us about feasibility of resections define oxidising and reducing agents steps in combining two half equations how to write cell notation where are electrochemical cells used what happen in the positive and negative electrodes of lithium cell what are fuel cells what are the benefits and risks

Answer 39

metal in solution of its ions 2 help equations with salt bridge wires and voltmeter, redox reaction happens, electrons travel from more reactive to less reactive metal salt bridge allow movement of ions eg -kno3 MOPRobelm negative emf is oxidise and positive emf is reduced OILRIG (FLIP half equation depending on if it reduced or oxidised) standard electrode potentials =0.00v its consists of 1 mol/dm-3 (might use h2so4 so half the moles) of h+ solution with pt electrode and h2 gas in 298k and 100kpa metal/ion//ion/metal positive emf value means its feasible pt can be used as electrode if both metal and ions are solution its conductive and unreactive non rechargeable cheaper rechargeable reversal long term eg lithium ion battery which ahs electrode a -lithium cobalt oxide electrode b graphite electrolyte lithium salt when recharging flip the reaction fuel cells need continuous supply of chemicals in a fuel cell h2 is pumped in and reacts with the oh- to create water and 4 e- and the electron move through anode platinum electrode to cathode platinum electrode where oxygen is pumped in where water reacts to make oh-and in the middle contains electrolytes for koh carries the oh- ions to anode advantages -fuel cells efficient, more energy converted to kinetic energy waste product only water disadvantages hydrogen highly farmable and expensive to transport

Question 40

* Define Boston lowery acid and bases * why a logarithmic scale used to mesure hydrogen ion concentartion * how do you find ph and h+ concentration

Answer 40

* Acid is a proton donor Bases are proton acceptors acid base reaction involves transfer of protons * Because the hydrogen ions in aqueous covers a very wide range * pH = –log10[H+] [H+]=10 to the power of (-pH)*

Question 41

what is kw equation where does it come from how dose temperature affect kw how to use it to find ph of strong acid

Answer 41

* kw=[H+][OH-] * The equation is the equilibrium conctant as water dssociates slightly * the forward reaction will be favoured, and more hydrogen ions and hydroxide ions will be formed. The effect of that is to increase the value of Kw as temperature increases. * kw will always equall (1times 10-14) and the [OH-] will be the same as the base concentartion so you can find [H+]

Question 42

what is the definition of a weak acid or base what is the equation for Ka (weak acid) how to find PKa from Ka and vise versa what are the unites

Answer 42

* They only dissociate slightly in aqueous solution * Ka=([H+][A−]/HA),or can be [H+]^2 * (pKa = –log10 Ka) (10^-pka) * mol dm-3

Question 43

* look through titration exam questions * explain how the graphs of combinations of a strong and weak acid and base would look like( look up) * what is an equivalance point * what are the different indicators used over different PH ranges and what are the color changes

Answer 43

* equivalance point is when a tiny amount od base causes a sudden change in ph (where the acid is nutrilised) * phenolphthalein - colourless to pink (8.3 to 10) * methyl orange - red to yellow (3.1 to 4.4) * strong acid / strong base = both methyl orange and phenolphthaline * strong acid / weak base = only methyl orange * weak acid / strong base = only phenolphthaline * wak acid / wak base = neither dosent works

Question 44

* what is the definition for buffer solutions * what is a acidic and basic buffer * what is a salt * where can buffers be used * explain what happen when there is a acid buffer and acid or bases is added from viodo * how to callculate ph of acidic buffer solution

Answer 44

* buffer maintains a constant ph when small amounts of acids and bases are added or dillution * Acidic buffer solutions contain a weak acid and the salt of that weak acid Basic buffer solutions contain a weak base and the salt of that weak base. * salt is a chemical compound formed from an acid when an H+ ion from the acid has been replaced by a metal ion or another positive ion * shampoos and biological washing powders * find moles using volum and concentartion take smaller mole from laregr mole and use the smaleer mole for oh- rearrange equation and find h+ find PH (look up)

Question 45

What are trends in first ionisation energy and melting point of the elements Na–Ar the explain it in terms of terms of the structure of and bonding in the elements. explain the trends in atomic radius and first ionisation energy explain the melting point of the elements in terms of their structure and bonding.

Question 46

The trends in atomic radius, first ionisation energy and melting point of the elements Mg–Ba Students should be able to: explain the trends in atomic radius and first ionisation energy explain the melting point of the elements in terms of their structure and bonding. The reactions of the elements Mg–Ba with water. The use of magnesium in the extraction of titanium from TiCl4 The relative solubilities of the hydroxides of the elements Mg–Ba in water. Mg(OH)2 is sparingly soluble. The use of Mg(OH)2 in medicine and of Ca(OH)2 in agriculture. The use of CaO or CaCO3 to remove SO2 from flue gases. The relative solubilities of the sulfates of the elements Mg–Ba in water. BaSO4 is insoluble. The use of acidified BaCl2 solution to test for sulfate ions. The use of BaSO4 in medicine. Students should be able to: explain why BaCl2 solution is used to test for sulfate ions and why it is acidified.

Question 47

properties are examined and explained. Fluorine is too dangerous to be used in a school laboratory properties of elements in this group include explaining the trends in ability of the halogens to behave as oxidising agents and the halide ions to behave as reducing agents. The trends in electronegativity and boiling point of the halogens. Students should be able to: explain the trend in electronegativity explain the trend in the boiling point of the elements in terms of their structure and bonding. The trend in oxidising ability of the halogens down the group, including displacement reactions of halide ions in aqueous solution. The trend in reducing ability of the halide ions, including the reactions of solid sodium halides with concentrated sulfuric acid. The use of acidified silver nitrate solution to identify and distinguish between halide ions. The trend in solubility of the silver halides in ammonia. Students should be able to explain why: silver nitrate solution is used to identify halide ions the silver nitrate solution is acidified ammonia solution is added.

Question 48

How reaction of chlorine with water to form chloride ions and chlorate(I) ions. How reaction of chlorine with water to form chloride ions and oxygen. What are some society assesses the advantages and disadvantages when deciding if chemicals should be added to water supplies. The use of chlorine in water treatment. Appreciate that the benefits to health of water treatment by chlorine outweigh its toxic effects. The reaction of chlorine with cold, dilute, aqueous NaOH and uses of the solution formed. Required practical 4Carry out simple test-tube reactions to identify: cations – Group 2, NH4+ anions – Group 7 (halide ions), OH–, CO32–, SO42

Question 49

The reactions of Na and Mg with water. The trends in the reactions of the elements Na, Mg, Al, Si, P and S with oxygen, limited to the formation of Na2O, MgO, Al2O3, SiO2, P4O10, SO2 and SO3 The trend in the melting point of the highest oxides of the elements Na–S The reactions of the oxides of the elements Na–S with water, limited to Na2O, MgO, Al2O3, SiO2, P4O10, SO2 and SO3, and the pH of the solutions formed. The structures of the acids and the anions formed when P4O10, SO2 and SO3 react with water. Students should be able to: explain the trend in the melting point of the oxides of the elements Na–S in terms of their structure and bonding explain the trends in the reactions of the oxides with water in terms of the type of bonding present in each oxide write equations for the reactions that occur between the oxides of the elements Na–S and given acids and bases.

Question 50

what is a monodentate, bidentate, and multidentate ligand give examples what are the 2 reasons why complex ligands can be replaced why might replacing h20 ligand with Cl- change co ordinate number why might a substitution reaction be incomplete what is haem how hemoglobin transports oxygen why is carbon monoxide toxic explain chetate effect what is the shape and angle of the complex if it has 6 coordinate bonds what is the shape and angle of the complex if it has 4 coordinate bonds what is needed to form an optical isomer for complex ions how can octahedral and square planer displaced as cis trans what is cisplatin's structure what is the linear complex formed with Ag

Answer 50

when one co ordinate bonds, eg H2O nh3 or Cl- when two co ordinated bonds eg ethane-1,2-diamine or ethanedioate when more than one co ordinate bonds eg EDTA^4- the ligands can form stronger coordinate bond or there's high concentration of ligand as cl- is larger than h2o only 4 ligands can be formed because theses not enough of ligands eg NH3 to replace the water ligands it is a multidentate ligand found in the molecule hemoglobin and forms 4 (nitrogen) out of the 6 ligands attached to fe2+, another two comes from globin and oxygen or water molecule oxygen is replaced by water when it reaches the muscle it attaches to the fe2+ and prevents oxygen from attaching as a ligand so oxygen is not transported The substitution of monodentate ligand with a bidentate or a multidentate ligand leads to a more stable complex. eg if 2 reactant molecules turn into 7 product molecules the entropy increases and reaction favor higher entropy octahedral with 90 degrees tetrahedral 109.5 degrees 3 bidentate ligands if the ligand of the same type is on opposite side then its trans if its on the same side then its cis for both octahedral and square planer they have 2 nh3 on top and 2 cl- on the bottom its a cis isomer it has ag with nh3 on both sides

Question 51

Name the different ions , oxidation states and colours of vanadium ions How to reduce vanadium Google the equation of each reductions of vanadium ions What are redox potentials What dose the redox potential tell us about the half equation In What environment is standard electrode potentials measured and what happen to the metal ion in this environment 2 reasons why redox potential might be higher or lower than the standard value What is a tollens reagent what is a redox titration fe2+,c2o4 2-,mno4- how do you balance a half equation

Answer 51

Zinc in acid solution (H+) Redox potential is the how easily an ion can be reduced same as electrode potentials More postive redox potential means it’s least stable and most likely to be reduced and that it’s more likely to be feasible It’s measured in aqueous solution so it will be surrounded by water ligand’s If stronger ligands such as NH3 attaches to the metal ion it may affect redox potential Or if the solution is more acidic means it would have larger electrode potentials therefore it would be easier to reduce It is a transition metal(silver) which forms a complex that helps distinguish between aldehydes and Ketons Cr2O7- (aq) + 14H+ (aq) + 6e- → 2Cr3+ (aq) + 7H2O (l) MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (aq) Fe2+ → Fe3+ +e- balance the moles balance oxygen by adding h20 to the other side balance the no of hydrogen on to the first side balance electron combining two equations-times equation by no of electrons

Question 52

what do ligands do to the d orbit explain how different colors are seen in terms of electrons and wavelengths what determines the color what does energy gap depend on what is the equation to find energy gap what is a spectroscopy used for and what can be used to find the absorbance

Answer 52

when ligands are formed the d orbital which has 5 sub shells splits, where one orbital will have a higher energy than the other when different wavelengths of light hit electron some are absorbed this cause electron to move up to the higher energy subshell and back, the wavelength of light not absorbed is reflected the energy energy gap of the split 3d sub shell determines the color the type of metal ions, oxidation state, type of ligands and the number of co ordinated bonds energy gap =plank constant (h) times frequency of light (hz) it can be used to find concentration of meatal ions, the more concentrated it is the more colored it is and the more light it absorbs which is recorded by the calorimeter

Question 53

why are transition metal good catalysis's what happen during a contact process what is a heterogeneous catalyst how can the rate of reaction be increased in heterogenous catalysts, what can they use to do this what are example of heterogenous catalyst and where there used what is catalyst poising, why might affect industries what are homogenous catalysts, give example what is an autocatalysis show the equation to how is mn3+formed from mn2+ to be the autocatalysis for c204^2-

Answer 53

the vacant d orbital means that that the oxidations states can change modern industrial method of producing sulfuric acid, during it v205 (vanadium) can go form 5+ to 4+ to oxidise so2 to so3 and vanadium goes back to 5+ oxidation by oxygen they are in a different phase from the reactants eg catalysts may be solid and the reacts are gases they would have to increase the rate of reaction this can be don by using a support medium they minimise the cost as only a small amount of medium is used to cover catalysts Fe in harbor cycle for making ammonia vanadium v204 in contact process making sulfuric acid Heterogeneous catalysts can become poisoned by impurities that block the active sites and consequently have reduced efficiency; this has a cost implication they are in the same phase as the reactants, the reaction go through an intermediate spices for example fe2+ haps catalyse s2o8^2- an I- as both are negative they repel so less likely to collide but fe2= is turned into fe 3+ byes s2o8^-2 and the the fe 3+ oxidise I- to make I homogeneous catalysts has the same physical state as the reactants, they combine with the reactants to form a intermediate spices with reacts again to create the products and the original catalyst its is the when the catalyst has to be made through a reaction and then this product acts as the catalyst 4Mn2+ (aq) + MnO4– (aq) + 8H+ (aq) → 5Mn3+ (aq) + 4H2O (aq) 2Mn3+ (aq) + C2O42- (aq) → 2CO2 (g) + 2Mn2+ (aq)

Question 54

what happens when transition metals dissolve in aquas solution why 3+metal aqua ions will form a more acidic solution than 2+ what happen when Oh- is added to metal aqua solution what is an amphoteric in terms of metal hydroxides give example show how the colour and the products formed when (cu2+,fe2+,al3+,fe3+) metal aqua ions react with oh-/nh3, excess oh-,excess nh3and na2co3

Answer 54

they become metal q=aqua ion complexes with six water ligands attached thro coordinate bons between electrons on the oxygen as 3+ ions have greater charge it is mor strongly bonded to the electron son the oxygen however this mean that the o-h bond on water is weaker so it more likely to split as a result more h+ ions are formed and is more acidic the oh reacts with the h30 causing the equlibrium to move to the left as a result the h2o ligands are replaced by 0h- according to the charge of the ion they can react with acid and base eg al hydroxides Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq) Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq) fe2+ [Fe(H2O)6] 2+ (aq) + 2OH– (aq) → Fe(H2O)4(OH)2 (s) + 2H2O (l) (green ppt) [Fe(H2O)6] 2+ (aq) + 2NH3 (aq) → Fe(H2O)4(OH)2 (s) + 2NH4+ (aq) (stays green solution -no change) [Fe(H2O)6] 2+ (aq) + CO32- (aq) → FeCO3 (s) + 6H2O (l) (green ppt) cu2+ [Cu(H2O)6] 2+ (aq) + 2OH– (aq) → Cu(H2O)4(OH)2 (s) +2 H2O (l) (blue ppt) [Cu(H2O)6] 2+ (aq) + 2NH3 (aq) → Cu(H2O)4(OH)2 (s) + 2NH4+ (aq) (not in exess same as oh- blur ppt) Cu(H2O)4(OH)2 (s) + 4NH3 (aq) → [Cu(NH3)4(H2O)2 ]2+ (aq) + + 2OH- (aq) + 2H2O (l)(in exess- deep blur solution) [Cu(H2O)6] 2+ (aq) + CO32- (aq) → CuCO3 (s) + 6H2O (l) (green blue ppt) al3+ [Al(H2O)6] 3+ (aq) +3 OH– (aq) → Al(H2O)3(OH)3 (s) + 3H2O (l) (white ppt) [Al(H2O)6] 3+ (aq) + 3NH3 (aq) → Al(H2O)3(OH)3 (s) + 3NH4+ (aq) (same as oh- white ppt) 2[Al(H2O)6]3+ + 3CO32− (aq) → 2Al(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)(white ppt) fe3+ [Fe(H2O)6] 3+ (aq) + 3OH– (aq) → Fe(H2O)3(OH)3 (s) + 3H2O (l) (brown ppt) [Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)(same as oh- brown ppt) 2[Fe(H2O)6]3+ (aq) + 3CO32− (aq) → 2Fe(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l) (brown ppt)

Question 55

Organic compounds can be represented by: empirical formula molecular formula general formula structural formula displayed formula skeletal formula. The characteristics of a homologous series, a series of compounds containing the same functional group. IUPAC rules for nomenclature. Students should be able to: draw structural, displayed and skeletal formulas for given organic compounds apply IUPAC rules for nomenclature to name organic compounds limited to chains and rings with up to six carbon atoms each apply IUPAC rules for nomenclature to draw the structure of an organic compound from the IUPAC name limited to chains and rings with up to six carbon atoms each.

Question 56

Opportunities for skills development Reactions of organic compounds can be explained using mechanisms. Free-radical mechanisms: the unpaired electron in a radical is represented by a dot the use of curly arrows is not required for radical mechanisms. Students should be able to: write balanced equations for the steps in a free-radical mechanism. Other mechanisms: the formation of a covalent bond is shown by a curly arrow that starts from a lone electron pair or from another covalent bond the breaking of a covalent bond is shown by a curly arrow starting from the bond. Students should be able to: outline mechanisms by drawing the structures of the species involved and curly arrows to represent the movement of electron pairs

Question 57

Structural isomerism. Stereoisomerism. E–Z isomerism is a form of stereoisomerism and occurs as a result of restricted rotation about the planar carbon–carbon double bond. Cahn–Ingold–Prelog (CIP) priority rules. Students should be able to: define the term structural isomer draw the structures of chain, position and functional group isomers define the term stereoisomer draw the structural formulas of E and Z isomers apply the CIP priority rules to E and Z isomers.

Question 58

Alkanes are saturated hydrocarbons. Petroleum is a mixture consisting mainly of alkane hydrocarbons that can be separated by fractional distillation.

Question 59

Cracking involves breaking C–C bonds in alkanes. Thermal cracking takes place at high pressure and high temperature and produces a high percentage of alkenes (mechanism not required). Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons (mechanism not required). Students should be able to: explain the economic reasons for cracking alkanes.

Question 60

Alkanes are used as fuels. Combustion of alkanes and other organic compounds can be complete or incomplete. The internal combustion engine produces a number of pollutants including NOx, CO, carbon and unburned hydrocarbons. These gaseous pollutants from internal combustion engines can be removed using catalytic converters. Combustion of hydrocarbons containing sulfur leads to sulfur dioxide that causes air pollution. Students should be able to: explain why sulfur dioxide can be removed from flue gases using calcium oxide or calcium carbonate.

Question 61

The reaction of methane with chlorine. Students should be able to: explain this reaction as a free-radical substitution mechanism involving initiation, propagation and termination steps.

Question 62

Halogenoalkanes contain polar bonds. Halogenoalkanes undergo substitution reactions with the nucleophiles OH–, CN– and NH3 Students should be able to: outline the nucleophilic substitution mechanisms of these reactions explain why the carbon–halogen bond enthalpy influences the rate of reaction.

Question 63

The concurrent substitution and elimination reactions of a halogenoalkane (eg 2-bromopropane with potassium hydroxide). Students should be able to: explain the role of the reagent as both nucleophile and base outline the mechanisms of these reactions.

Question 64

Ozone, formed naturally in the upper atmosphere, is beneficial because it absorbs ultraviolet radiation. Chlorine atoms are formed in the upper atmosphere when ultraviolet radiation causes C–Cl bonds in chlorofluorocarbons (CFCs) to break. Chlorine atoms catalyse the decomposition of ozone and contribute to the hole in the ozone layer. Appreciate that results of research by different groups in the scientific community provided evidence for legislation to ban the use of CFCs as solvents and refrigerants. Chemists have now developed alternative chlorine-free compounds. Students should be able to: use equations, such as the following, to explain how chlorine atoms catalyse decomposition of ozone: Cl• + O3 → ClO• + O2 and ClO• + O3 → 2O2 + Cl•

Question 65

Alkenes are unsaturated hydrocarbons. Bonding in alkenes involves a double covalent bond, a centre of high electron density.

Question 66

Electrophilic addition reactions of alkenes with HBr, H2SO4 and Br2 The use of bromine to test for unsaturation. The formation of major and minor products in addition reactions of unsymmetrical alkenes. Students should be able to: outline the mechanisms for these reactions explain the formation of major and minor products by reference to the relative stabilities of primary, secondary and tertiary carbocation intermediates.

Question 67

Addition polymers are formed from alkenes and substituted alkenes. The repeating unit of addition polymers. IUPAC rules for naming addition polymers. Addition polymers are unreactive. Appreciate that knowledge and understanding of the production and properties of polymers has developed over time. Typical uses of poly(chloroethene), commonly known as PVC, and how its properties can be modified using a plasticiser. Students should be able to: draw the repeating unit from a monomer structure draw the repeating unit from a section of the polymer chain draw the structure of the monomer from a section of the polymer explain why addition polymers are unreactive explain the nature of intermolecular forces between molecules of polyalkenes.

Question 68

Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst. Ethanol is produced industrially by fermentation of glucose. The conditions for this process. Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a biofuel. Students should be able to: explain the meaning of the term biofuel justify the conditions used in the production of ethanol by fermentation of glucose write equations to support the statement that ethanol produced by fermentation is a carbon neutral fuel and give reasons why this statement is not valid outline the mechanism for the formation of an alcohol by the reaction of an alkene with steam in the presence of an acid catalyst discuss the environmental (including ethical) issues linked to decision making about biofuel use.

Question 69

Alcohols are classified as primary, secondary and tertiary. Primary alcohols can be oxidised to aldehydes which can be further oxidised to carboxylic acids. Secondary alcohols can be oxidised to ketones. Tertiary alcohols are not easily oxidised. Acidified potassium dichromate(VI) is a suitable oxidising agent. Students should be able to: write equations for these oxidation reactions (equations showing [O] as oxidant are acceptable) explain how the method used to oxidise a primary alcohol determines whether an aldehyde or carboxylic acid is obtained use chemical tests to distinguish between aldehydes and ketones including Fehling’s solution and Tollens’ reagent.

Question 70

Alkenes can be formed from alcohols by acid-catalysed elimination reactions. Alkenes produced by this method can be used to produce addition polymers without using monomers derived from crude oil. Students should be able to: outline the mechanism for the elimination of water from alcohols. AT b, d, g and k PS 4.1 Students could carry out the preparation of cyclohexene from cyclohexanol, including purification using a separating funnel and by distillation. Required practical 5 Distillation of a product from a reaction.

Question 71

The reactions of functional groups listed in the specification. Students should be able to: identify the functional groups using reactions in the specification. AT b, d and k PS 2.2, 2.3 and 4.1 Students could carry out test-tube reactions in the specification to distinguish alcohols, aldehydes, alkenes and carboxylic acids. Required practical 6 Tests for alcohol, aldehyde, alkene and carboxylic acid.

Question 72

Mass spectrometry can be used to determine the molecular formula of a compound. Students should be able to: use precise atomic masses and the precise molecular mass to determine the molecular formula of a compound.

Question 73

Bonds in a molecule absorb infrared radiation at characteristic wavenumbers. ‘Fingerprinting’ allows identification of a molecule by comparison of spectra. Students should be able to: use infrared spectra and the Chemistry Data Sheet or Booklet to identify particular bonds, and therefore functional groups, and also to identify impurities. The link between absorption of infrared radiation by bonds in CO2, methane and water vapour and global warming.

Question 74

Optical isomerism is a form of stereoisomerism and occurs as a result of chirality in molecules, limited to molecules with a single chiral centre. An asymmetric carbon atom is chiral and gives rise to optical isomers (enantiomers), which exist as non super-imposable mirror images and differ in their effect on plane polarised light. A mixture of equal amounts of enantiomers is called a racemic mixture (racemate). Students should be able to: draw the structural formulas and displayed formulas of enantiomers understand how racemic mixtures (racemates) are formed and why they are optically inactive.

Question 75

Aldehydes are readily oxidised to carboxylic acids. Chemical tests to distinguish between aldehydes and ketones including Fehling’s solution and Tollens’ reagent. Aldehydes can be reduced to primary alcohols, and ketones to secondary alcohols, using NaBH4 in aqueous solution. These reduction reactions are examples of nucleophilic addition. The nucleophilic addition reactions of carbonyl compounds with KCN, followed by dilute acid, to produce hydroxynitriles. Aldehydes and unsymmetrical ketones form mixtures of enantiomers when they react with KCN followed by dilute acid. The hazards of using KCN. Students should be able to: write overall equations for reduction reactions using [H] as the reductant outline the nucleophilic addition mechanism for reduction reactions with NaBH4 (the nucleophile should be shown as H–) write overall equations for the formation of hydroxynitriles using HCN outline the nucleophilic addition mechanism for the reaction with KCN followed by dilute acid explain why nucleophilic addition reactions of KCN, followed by dilute acid, can produce a mixture of enantiomers.

Question 76

The structures of: carboxylic acids esters. Carboxylic acids are weak acids but will liberate CO2 from carbonates. Carboxylic acids and alcohols react, in the presence of an acid catalyst, to give esters. Common uses of esters (eg in solvents, plasticisers, perfumes and food flavourings). Vegetable oils and animal fats are esters of propane-1,2,3-triol (glycerol). Esters can be hydrolysed in acid or alkaline conditions to form alcohols and carboxylic acids or salts of carboxylic acids. Vegetable oils and animal fats can be hydrolysed in alkaline conditions to give soap (salts of long-chain carboxylic acids) and glycerol. Biodiesel is a mixture of methyl esters of long-chain carboxylic acids. Biodiesel is produced by reacting vegetable oils with methanol in the presence of a catalyst.

Question 77

The structures of: acid anhydrides acyl chlorides amides. The nucleophilic addition–elimination reactions of water, alcohols, ammonia and primary amines with acyl chlorides and acid anhydrides. The industrial advantages of ethanoic anhydride over ethanoyl chloride in the manufacture of the drug aspirin. Students should be able to outline the mechanism of nucleophilic addition–elimination reactions of acyl chlorides with water, alcohols, ammonia and primary amines. Required practical 10 Preparation of: a pure organic solid and test of its purity a pure organic liquid.

Question 78

The nature of the bonding in a benzene ring, limited to planar structure and bond length intermediate between single and double. Delocalisation of p electrons makes benzene more stable than the theoretical molecule cyclohexa-1,3,5-triene. Students should be able to: use thermochemical evidence from enthalpies of hydrogenation to account for this extra stability explain why substitution reactions occur in preference to addition reactions.

Question 79

Electrophilic attack on benzene rings results in substitution, limited to monosubstitutions. Nitration is an important step in synthesis, including the manufacture of explosives and formation of amines. Friedel–Crafts acylation reactions are also important steps in synthesis. Students should be able to outline the electrophilic substitution mechanisms of: nitration, including the generation of the nitronium ion acylation using AlCl3 as a catalyst.

Question 80

Primary aliphatic amines can be prepared by the reaction of ammonia with halogenoalkanes and by the reduction of nitriles. Aromatic amines, prepared by the reduction of nitro compounds, are used in the manufacture of dyes.

Question 81

Amines are weak bases. The difference in base strength between ammonia, primary aliphatic and primary aromatic amines. Students should be able to: explain the difference in base strength in terms of the availability of the lone pair of electrons on the N atom.

Question 82

Amines are nucleophiles. The nucleophilic substitution reactions of ammonia and amines with halogenoalkanes to form primary, secondary, tertiary amines and quaternary ammonium salts. The use of quaternary ammonium salts as cationic surfactants. The nucleophilic addition–elimination reactions of ammonia and primary amines with acyl chlorides and acid anhydrides. Students should be able to outline the mechanisms of: these nucleophilic substitution reactions the nucleophilic addition–elimination reactions of ammonia and primary amines with acyl chlorides.

Question 83

Condensation polymers are formed by reactions between: dicarboxylic acids and diols dicarboxylic acids and diamines amino acids. The repeating units in polyesters (eg Terylene) and polyamides (eg nylon 6,6 and Kevlar) and the linkages between these repeating units. Typical uses of these polymers. Students should be able to: draw the repeating unit from monomer structure(s) draw the repeating unit from a section of the polymer chain draw the structure(s) of the monomer(s) from a section of the polymer explain the nature of the intermolecular forces between molecules of condensation polymers.

Question 84

Polyalkenes are chemically inert and non-biodegradable. Polyesters and polyamides can be broken down by hydrolysis and are biodegradable. The advantages and disadvantages of different methods of disposal of polymers, including recycling. Students should be able to: explain why polyesters and polyamides can be hydrolysed but polyalkenes cannot.

Question 85

Amino acids have both acidic and basic properties, including the formation of zwitterions. Students should be able to draw the structures of amino acids as zwitterions and the ions formed from amino acids: in acid solution in alkaline solution.

Question 86

Proteins are sequences of amino acids joined by peptide links. The importance of hydrogen bonding and sulfur–sulfur bonds in proteins. The primary, secondary (α-helix and β–pleated sheets) and tertiary structure of proteins. Hydrolysis of the peptide link produces the constituent amino acids. Amino acids can be separated and identified by thin-layer chromatography. Amino acids can be located on a chromatogram using developing agents such as ninhydrin or ultraviolet light and identified by their Rf values. Students should be able to: draw the structure of a peptide formed from up to three amino acids draw the structure of the amino acids formed by hydrolysis of a peptide identify primary, secondary and tertiary structures in diagrams explain how these structures are maintained by hydrogen bonding and S–S bonds calculate Rf values from a chromatogram

Question 87

Enzymes are proteins. The action of enzymes as catalysts, including the concept of a stereospecific active site that binds to a substrate molecule. The principle of a drug acting as an enzyme inhibitor by blocking the active site. Computers can be used to help design such drugs. Students should be able to: explain why a stereospecific active site can only bond to one enantiomeric form of a substrate or drug.

Question 88

The structures of the phosphate ion, 2-deoxyribose (a pentose sugar) and the four bases adenine, cytosine, guanine and thymine are given in the Chemistry Data Booklet. A nucleotide is made up from a phosphate ion bonded to 2-deoxyribose which is in turn bonded to one of the four bases adenine, cytosine, guanine and thymine. A single strand of DNA (deoxyribonucleic acid) is a polymer of nucleotides linked by covalent bonds between the phosphate group of one nucleotide and the 2-deoxyribose of another nucleotide. This results in a sugar-phosphate-sugar-phosphate polymer chain with bases attached to the sugars in the chain. DNA exists as two complementary strands arranged in the form of a double helix. Students should be able to: explain how hydrogen bonding between base pairs leads to the two complementary strands of DNA.

Question 89

The Pt(II) complex cisplatin is used as an anticancer drug. Cisplatin prevents DNA replication in cancer cells by a ligand replacement reaction with DNA in which a bond is formed between platinum and a nitrogen atom on guanine. Appreciate that society needs to assess the balance between the benefits and the adverse effects of drugs, such as the anticancer drug cisplatin. Students should be able to: explain why cisplatin prevents DNA replication explain why such drugs can have adverse effects.

Question 90

The synthesis of an organic compound can involve several steps. Students should be able to: explain why chemists aim to design processes that do not require a solvent and that use non-hazardous starting materials explain why chemists aim to design production methods with fewer steps that have a high percentage atom economy use reactions in this specification to devise a synthesis, with up to four steps, for an organic compound.

Question 91

Appreciation that scientists have developed a range of analytical techniques which together enable the structures of new compounds to be confirmed. Nuclear magnetic resonance (NMR) gives information about the position of 13C or 1H atoms in a molecule. 13C NMR gives simpler spectra than 1H NMR. The use of the δ scale for recording chemical shift. Chemical shift depends on the molecular environment. Integrated spectra indicate the relative numbers of 1H atoms in different environments. 1H NMR spectra are obtained using samples dissolved in deuterated solvents or CCl4 The use of tetramethylsilane (TMS) as a standard. Students should be able to: explain why TMS is a suitable substance to use as a standard use 1H NMR and 13C NMR spectra and chemical shift data from the Chemistry Data Booklet to suggest possible structures or part structures for molecules use integration data from 1H NMR spectra to determine the relative numbers of equivalent protons in the molecule use the n+1 rule to deduce the spin–spin splitting patterns of adjacent, non-equivalent protons, limited to doublet, triplet and quartet formation in aliphatic compounds.

Question 92

Chromatography can be used to separate and identify the components in a mixture. Types of chromatography include: thin-layer chromatography (TLC) – a plate is coated with a solid and a solvent moves up the plate column chromatography (CC) – a column is packed with a solid and a solvent moves down the column gas chromatography (GC) – a column is packed with a solid or with a solid coated by a liquid, and a gas is passed through the column under pressure at high temperature. Separation depends on the balance between solubility in the moving phase and retention by the stationary phase. Retention times and Rf values are used to identify different substances. The use of mass spectrometry to analyse the components separated by GC. Students should be able to: calculate Rf values from a chromatogram compare retention times and Rf values with standards to identify different substances

Question 93

what happen when mg and na reacts with water which is more reactive what elements to know about in this section how they react with air what happens when period 3 elements react with oxygen what meting point of period 3 metal oxides why dose na2o produce solution with huger ph than MgO a sthe hydroxide produced by na 2o is more soluble in water tha mgO

Answer 93

na+ and mg2+ is formed, na is more reactive as i is easier to reove an electron from na than mg (manisum /sodium hydroxideoxide and h2is formed) with staem it forms metal oxide instaed of hydroxides na mg(reacts vigarously) al si(reacts slowly) p(spontanious combustion) s (burns) they from oxides eg na 20,mgo,sio2,p4o10 na2o and al2o3 adn mg2o has gain ionic structure so hig mp mgo higer as it has 2+ so hardeer to remove electron alo3 low electronegtivity between al and o so easler to get electron si has covalent bonds p4o10 so2 simple molecular structure