Chemistry Unit 2 Notes

21-Shapes of molecules and ions

Electron-pair repulsion theory The shape of a molecule or an ion depends on the number of electron pairs that surround the atom The electron pairs repel each other so stay far apart from each other

Linear 2 electron pairs 180˚ bond angles (eg BeCl2 CO2)Trigonal Planar 3 electron pairs 120˚ bond angles (eg BCl3)Bent 2 electron pairs 1 lone pair Tetrahedral 4 electron pairs 1095˚ bond angles (eg CH4 NH4

+)Trigonal Pyramidal 3 electron pairs 1 lone pair 107˚ bond angles between electron pairs (eg NH3)Bent 2 electron pairs 2 lone pairs 1045˚ bond angles between electron pairs (eg H20)Trigonal bipyramidal 5 electron pairs 90˚ and 120˚ bond angles (eg PCl5)Octahedral 6 electron pairs 90˚ and 180˚ bond angles (eg SF6)

Lone pairs and doubletriple bonds repel more than electron pairs hence the differences in angles even with 4 3 bonds

Alkanes Tetrahedral due to all bond angles being 1095˚ due to carbon forming 4 bondsAlkenes Bonds around the double bond are trigonal planar but due to the double bond the bond angles can range from 121˚-118˚Alcohols Hydrocarbon chain is tetrahedral so bond angles are 1095˚ C-O-H bond is a bent molecule so is 1045˚Carboxylic acids -COOH group around the carbon is trigonal planar so 120˚Haloalkanes Tetrahedral as halogen bonds donrsquot affect bond angles Same as alkanesCarbonyls CHOC=0 bonds around the carbon are trigonal planar (120˚)

Diamond Tetrahedral due to 4 carbon electron pairs being formedGraphite Trigonal planar as only 3 carbon electron pairs are formed Good conductor due to weak London forcesFullerene Spherical molecule made up of about 60 carbon atoms which can dissolve in petrol and is a good conductorNanotubes Tube-like cage structure made up of 12 membered rings that can be used to carry drugs to target body cells

22-intermediate bonding and bond polarity

Electronegativity A measure of the attraction of an atom in a molecule for a pair of electrons in a covalent bond

Fluorine is the most electronegative as it has the least shielding whilst still having a large number of protons so has a greater pull

Covalent bond Shared electrons Ionic bond Loss of electrons by metal and gain of electrons by non-metal Both are two extremes of the spectrum

Differences between electronegativities of atoms can determine what percentage of each character (covalent or Ionic) they are Looking at the electron cloud around the bond can also determine their character Polar covalent bonds will have an even spread of charge whereas Ionic bonds will show a distortion in the electron cloud around one atom

Non-symmetrical molecules tend to be polar so will produce a clear dipole (eg Trichloromethane) with a known polarity measured in dipole moment (Debye D)

Symmetrical molecules are non-polar due to the dipoles cancelling (eg CO2)

23-Intermolecular forces

Types of Intermolecular forces

Permanent dipoles Polar molecules only Negative dipole attracted to the Positive dipole and vice versa 100x weaker than covalent bondingLondon forces Electrons distributed around the nucleus change so more electrons are distributed around one end This induces another atom thatrsquos near it to do the same So a weak temporary bonding forms between the two atoms Is a weak force but strength does depend on the size of the electron cloud More electrons=more delocalisation=more London forcesHydrogen bonding Hydrogen attached to a very electronegative element (eg fluorine oxygen and nitrogen) This is the strongest intermolecular force

Boiling temperature trends (determined by intermolecular forces)

Alkanes with increasing chain length Increasing boiling temperature due to increasing London forces with the increase in the number of electronsBranching in the carbon chain The boiling temperature decreases This is because the side chains interfere with the packing of the molecule Molecules canrsquot form many intermolecular forcesAlcohols Have hydrogen bonds present so have high boiling temperatures Water has a higher boiling temperature than alcohols as it can form double the amount of Hydrogen bondsHydrogen halides down the period Fluorine is highly electronegative so has a very large boiling temperature compared to the rest which from chlorine starts low around -80˚ and then gradually increases due to increased dipole-dipole interactions from increased number of electrons

Solubility trends

A solution is made up of a solute and a solvent Table below shows the solubility of different substances Ketone is unusual in that it can dissolve in both water and organic solvents as it has both of the functional groups

Formula Description EgPolar

AB Linear COHA Single H HClAxOH OH at one end C2H5OHNxAy N at one end NH3

Non-polar

A2 All elements O2

CxAy Carbon compounds

CO2

24-Redox

Oxidation no amount of charge due to no of electrons

Rules

Atom Oxidation noElements 0Uncombined ion Itrsquos chargeMolecule total 0Fluorine -1Hydrogen +1 (except metal hydrides=-1)Oxygen -2 (except peroxides=-1 and with

fluorine=positive no)Chlorine -1 (except with oxygen or

fluorine=positive no)Group 1 2 3 +1 +2 +3 respectively

OILRIG Oxidation is loss Reduction is gain

Reducing agent Reduces another substance whilst being oxidised itself

Oxidising agent Oxidises a substance whilst being reduced itself

Reduction half equation Cl2(g) + 2e- 2Cl-(aq)

Oxidation half equation 2I-(aq) I2(s) + 2e-

Key half equations 02(g) +4e- 202-(s)

2H20(l) +2e- 2OH-(aq) +H2(g)

2H+(aq) +2e- H2(g)

Displacement One substance replaces another in a reaction

Highly Polar solids

Polar organic substances

Non-polar solids

Ionic compound (eg NaCl)

Non-polar liquids

Water soluble soluble insoluble Soluble (Hydration enthalpy)

Hexane insoluble insoluble solublePolar liquids

Immiscible (forms two separate layers)

Non-polar liquids

miscible

Disproportionation Where a substance is both oxidised and reduced in a reaction

Common Oxidising Agents Common Reducing agentsO2+4e- 2O2- M Mn++e- (metal)Cl2+2e- 2Cl- Fe2+ Fe3++e-

Br2+2e- 2Br- 2I- I2+2e-

I2+2e- 2I- 2S2O32- S4O6

2-+2e-

Fe3++e- Fe2+ C2O42- 2CO2+2e-

2H++2e- H2 H2O2 O2+2H++2e-

Mn04-+8e- Mn2++4H2O S03

2-+H2O SO42-+2H++2e-

Cr2O72-+14H++6e- 2Cr3++7H2O

2H2SO4+2e- SO42-+2H2O+SO2

25-Periodic Table

Group 2

Trend in 1st Ionisation energy Decreases down the group due to increasing atomic radius where the outer electrons are further away so less energy is needed to remove an electron Forms 2+ ions easily

Reactions- With Oxygen Burns brightly to produce a metal oxide with increasing reactivity down the groupWith Chlorine Solid metal chloride formed Also has an increase in reactivityWith Water Increasing reactivity down group Beryllium has no reaction Magnesium only reacts with steam to produce a magnesium oxide and the rest react with cold water to produce metal hydroxidesOxides with Water Increasing reactivity Beryllium and magnesium only react slightly Calcium fizzes to produce calcium hydroxide (slaking lime) and strontium and Barium react in a similar wayOxidesHydroxides with Dilute Acids Forms a salt and water Eg CaCl2+ H2O or Ca(NO3)2+H2O

Flame Testing Place nichrome wire in concentrated HCl then heat in a bunsen flame to clean Colours of flames are shown in table

Solubility

Of hydroxides Increases down groupOf Sulphates Decreases down groupThermal StabilityOf Nitrates Decreases down group 1 due to weaker charge of attraction Group 1 are more stable than group 2 apart from lithium due to larger charge 2NaNO3 2NaNO2+O2 4liNO3 2Li2O+4NO2+O2 2Mg(NO3)2 2MgO+4NO2+O2

Of Carbonates More stable as you go down the group as cations get bigger so there is a more polarising effect on the carbonate

Group7-Halogens

Cation Flame ColourLithium RedSodium YellowPotassium LilacMagnesium

No colour

Calcium OrangeRedStrontium RedBarium Pale Green

Solubility

In Water Chlorine forms chlorine water which is colourless Bromine water is Orange Iodine isnrsquot soluble in water as it needs I3- ions so instead it dissolves in Potassium iodide which is BrownIn organic solvents As halogens are non-polar they dissolve more easily in hydrocarbon solvents than water Chlorine= Pale yellow Bromine=Brown Iodine=Purple

Oxidisation reactions

Halogens are strong oxidising agents

With metals Form salts 2Fe+3Cl2 2FeCl3 Fe+I2 FeI2

With Hydrogen Decreasing reactivity down group Chlorine explodes whereas Bromine and Iodine need 300˚C and Platinum catalystWith Phosphorus Chorine forms a chloride (III) then a chloride (V)With Iron Chloride Green iron (II) chloride becomes oxidised to brown iron (III) chloride

Chlorine is a stronger oxidising agent than iodine 2KI-+Cl2 2KCl+I2

Sulphuric acid oxidises halides and halogens with increasing vigour down the group

Hydrogen Halides are covalent but become increasingly ionic as you go up the group

Hydrogen Halides and Ammonia NH3+HCl NH4Cl

Disproportionation reactions

With cold dilute Alkali Cl2+2OH- Cl-+ClO-+H2OWith warm Alkali 3ClO- 2Cl-+ClO3

-

Testing for halogens

Silver halides AgCl-White precipitate which is soluble in ammonia AgBr- Cream precipitate which is soluble in ammonia AgI- Yellow precipitate which is insoluble in ammonia

Concentrated sulphuric acid and glass rod with ammonia Chlorine=white fumes white smoke Bromine=white and orange fumes white smoke Iodine=White and purple fumes white smoke

26-Kinetics

Rate of reaction Speed with which reactants disappear and products are formed for a particular reaction

Decreased rate=Decreased yield

Factors in rate of reaction

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Differences between electronegativities of atoms can determine what percentage of each character (covalent or Ionic) they are Looking at the electron cloud around the bond can also determine their character Polar covalent bonds will have an even spread of charge whereas Ionic bonds will show a distortion in the electron cloud around one atom

Non-symmetrical molecules tend to be polar so will produce a clear dipole (eg Trichloromethane) with a known polarity measured in dipole moment (Debye D)

Symmetrical molecules are non-polar due to the dipoles cancelling (eg CO2)

23-Intermolecular forces

Types of Intermolecular forces

Permanent dipoles Polar molecules only Negative dipole attracted to the Positive dipole and vice versa 100x weaker than covalent bondingLondon forces Electrons distributed around the nucleus change so more electrons are distributed around one end This induces another atom thatrsquos near it to do the same So a weak temporary bonding forms between the two atoms Is a weak force but strength does depend on the size of the electron cloud More electrons=more delocalisation=more London forcesHydrogen bonding Hydrogen attached to a very electronegative element (eg fluorine oxygen and nitrogen) This is the strongest intermolecular force

Boiling temperature trends (determined by intermolecular forces)

Alkanes with increasing chain length Increasing boiling temperature due to increasing London forces with the increase in the number of electronsBranching in the carbon chain The boiling temperature decreases This is because the side chains interfere with the packing of the molecule Molecules canrsquot form many intermolecular forcesAlcohols Have hydrogen bonds present so have high boiling temperatures Water has a higher boiling temperature than alcohols as it can form double the amount of Hydrogen bondsHydrogen halides down the period Fluorine is highly electronegative so has a very large boiling temperature compared to the rest which from chlorine starts low around -80˚ and then gradually increases due to increased dipole-dipole interactions from increased number of electrons

Solubility trends

A solution is made up of a solute and a solvent Table below shows the solubility of different substances Ketone is unusual in that it can dissolve in both water and organic solvents as it has both of the functional groups

Formula Description EgPolar

AB Linear COHA Single H HClAxOH OH at one end C2H5OHNxAy N at one end NH3

Non-polar

A2 All elements O2

CxAy Carbon compounds

CO2

24-Redox

Oxidation no amount of charge due to no of electrons

Rules

Atom Oxidation noElements 0Uncombined ion Itrsquos chargeMolecule total 0Fluorine -1Hydrogen +1 (except metal hydrides=-1)Oxygen -2 (except peroxides=-1 and with

fluorine=positive no)Chlorine -1 (except with oxygen or

fluorine=positive no)Group 1 2 3 +1 +2 +3 respectively

OILRIG Oxidation is loss Reduction is gain

Reducing agent Reduces another substance whilst being oxidised itself

Oxidising agent Oxidises a substance whilst being reduced itself

Reduction half equation Cl2(g) + 2e- 2Cl-(aq)

Oxidation half equation 2I-(aq) I2(s) + 2e-

Key half equations 02(g) +4e- 202-(s)

2H20(l) +2e- 2OH-(aq) +H2(g)

2H+(aq) +2e- H2(g)

Displacement One substance replaces another in a reaction

Highly Polar solids

Polar organic substances

Non-polar solids

Ionic compound (eg NaCl)

Non-polar liquids

Water soluble soluble insoluble Soluble (Hydration enthalpy)

Hexane insoluble insoluble solublePolar liquids

Immiscible (forms two separate layers)

Non-polar liquids

miscible

Disproportionation Where a substance is both oxidised and reduced in a reaction

Common Oxidising Agents Common Reducing agentsO2+4e- 2O2- M Mn++e- (metal)Cl2+2e- 2Cl- Fe2+ Fe3++e-

Br2+2e- 2Br- 2I- I2+2e-

I2+2e- 2I- 2S2O32- S4O6

2-+2e-

Fe3++e- Fe2+ C2O42- 2CO2+2e-

2H++2e- H2 H2O2 O2+2H++2e-

Mn04-+8e- Mn2++4H2O S03

2-+H2O SO42-+2H++2e-

Cr2O72-+14H++6e- 2Cr3++7H2O

2H2SO4+2e- SO42-+2H2O+SO2

25-Periodic Table

Group 2

Trend in 1st Ionisation energy Decreases down the group due to increasing atomic radius where the outer electrons are further away so less energy is needed to remove an electron Forms 2+ ions easily

Reactions- With Oxygen Burns brightly to produce a metal oxide with increasing reactivity down the groupWith Chlorine Solid metal chloride formed Also has an increase in reactivityWith Water Increasing reactivity down group Beryllium has no reaction Magnesium only reacts with steam to produce a magnesium oxide and the rest react with cold water to produce metal hydroxidesOxides with Water Increasing reactivity Beryllium and magnesium only react slightly Calcium fizzes to produce calcium hydroxide (slaking lime) and strontium and Barium react in a similar wayOxidesHydroxides with Dilute Acids Forms a salt and water Eg CaCl2+ H2O or Ca(NO3)2+H2O

Flame Testing Place nichrome wire in concentrated HCl then heat in a bunsen flame to clean Colours of flames are shown in table

Solubility

Of hydroxides Increases down groupOf Sulphates Decreases down groupThermal StabilityOf Nitrates Decreases down group 1 due to weaker charge of attraction Group 1 are more stable than group 2 apart from lithium due to larger charge 2NaNO3 2NaNO2+O2 4liNO3 2Li2O+4NO2+O2 2Mg(NO3)2 2MgO+4NO2+O2

Of Carbonates More stable as you go down the group as cations get bigger so there is a more polarising effect on the carbonate

Group7-Halogens

Cation Flame ColourLithium RedSodium YellowPotassium LilacMagnesium

No colour

Calcium OrangeRedStrontium RedBarium Pale Green

Solubility

In Water Chlorine forms chlorine water which is colourless Bromine water is Orange Iodine isnrsquot soluble in water as it needs I3- ions so instead it dissolves in Potassium iodide which is BrownIn organic solvents As halogens are non-polar they dissolve more easily in hydrocarbon solvents than water Chlorine= Pale yellow Bromine=Brown Iodine=Purple

Oxidisation reactions

Halogens are strong oxidising agents

With metals Form salts 2Fe+3Cl2 2FeCl3 Fe+I2 FeI2

With Hydrogen Decreasing reactivity down group Chlorine explodes whereas Bromine and Iodine need 300˚C and Platinum catalystWith Phosphorus Chorine forms a chloride (III) then a chloride (V)With Iron Chloride Green iron (II) chloride becomes oxidised to brown iron (III) chloride

Chlorine is a stronger oxidising agent than iodine 2KI-+Cl2 2KCl+I2

Sulphuric acid oxidises halides and halogens with increasing vigour down the group

Hydrogen Halides are covalent but become increasingly ionic as you go up the group

Hydrogen Halides and Ammonia NH3+HCl NH4Cl

Disproportionation reactions

With cold dilute Alkali Cl2+2OH- Cl-+ClO-+H2OWith warm Alkali 3ClO- 2Cl-+ClO3

-

Testing for halogens

Silver halides AgCl-White precipitate which is soluble in ammonia AgBr- Cream precipitate which is soluble in ammonia AgI- Yellow precipitate which is insoluble in ammonia

Concentrated sulphuric acid and glass rod with ammonia Chlorine=white fumes white smoke Bromine=white and orange fumes white smoke Iodine=White and purple fumes white smoke

26-Kinetics

Rate of reaction Speed with which reactants disappear and products are formed for a particular reaction

Decreased rate=Decreased yield

Factors in rate of reaction

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

24-Redox

Oxidation no amount of charge due to no of electrons

Rules

Atom Oxidation noElements 0Uncombined ion Itrsquos chargeMolecule total 0Fluorine -1Hydrogen +1 (except metal hydrides=-1)Oxygen -2 (except peroxides=-1 and with

fluorine=positive no)Chlorine -1 (except with oxygen or

fluorine=positive no)Group 1 2 3 +1 +2 +3 respectively

OILRIG Oxidation is loss Reduction is gain

Reducing agent Reduces another substance whilst being oxidised itself

Oxidising agent Oxidises a substance whilst being reduced itself

Reduction half equation Cl2(g) + 2e- 2Cl-(aq)

Oxidation half equation 2I-(aq) I2(s) + 2e-

Key half equations 02(g) +4e- 202-(s)

2H20(l) +2e- 2OH-(aq) +H2(g)

2H+(aq) +2e- H2(g)

Displacement One substance replaces another in a reaction

Highly Polar solids

Polar organic substances

Non-polar solids

Ionic compound (eg NaCl)

Non-polar liquids

Water soluble soluble insoluble Soluble (Hydration enthalpy)

Hexane insoluble insoluble solublePolar liquids

Immiscible (forms two separate layers)

Non-polar liquids

miscible

Disproportionation Where a substance is both oxidised and reduced in a reaction

Common Oxidising Agents Common Reducing agentsO2+4e- 2O2- M Mn++e- (metal)Cl2+2e- 2Cl- Fe2+ Fe3++e-

Br2+2e- 2Br- 2I- I2+2e-

I2+2e- 2I- 2S2O32- S4O6

2-+2e-

Fe3++e- Fe2+ C2O42- 2CO2+2e-

2H++2e- H2 H2O2 O2+2H++2e-

Mn04-+8e- Mn2++4H2O S03

2-+H2O SO42-+2H++2e-

Cr2O72-+14H++6e- 2Cr3++7H2O

2H2SO4+2e- SO42-+2H2O+SO2

25-Periodic Table

Group 2

Trend in 1st Ionisation energy Decreases down the group due to increasing atomic radius where the outer electrons are further away so less energy is needed to remove an electron Forms 2+ ions easily

Reactions- With Oxygen Burns brightly to produce a metal oxide with increasing reactivity down the groupWith Chlorine Solid metal chloride formed Also has an increase in reactivityWith Water Increasing reactivity down group Beryllium has no reaction Magnesium only reacts with steam to produce a magnesium oxide and the rest react with cold water to produce metal hydroxidesOxides with Water Increasing reactivity Beryllium and magnesium only react slightly Calcium fizzes to produce calcium hydroxide (slaking lime) and strontium and Barium react in a similar wayOxidesHydroxides with Dilute Acids Forms a salt and water Eg CaCl2+ H2O or Ca(NO3)2+H2O

Flame Testing Place nichrome wire in concentrated HCl then heat in a bunsen flame to clean Colours of flames are shown in table

Solubility

Of hydroxides Increases down groupOf Sulphates Decreases down groupThermal StabilityOf Nitrates Decreases down group 1 due to weaker charge of attraction Group 1 are more stable than group 2 apart from lithium due to larger charge 2NaNO3 2NaNO2+O2 4liNO3 2Li2O+4NO2+O2 2Mg(NO3)2 2MgO+4NO2+O2

Of Carbonates More stable as you go down the group as cations get bigger so there is a more polarising effect on the carbonate

Group7-Halogens

Cation Flame ColourLithium RedSodium YellowPotassium LilacMagnesium

No colour

Calcium OrangeRedStrontium RedBarium Pale Green

Solubility

In Water Chlorine forms chlorine water which is colourless Bromine water is Orange Iodine isnrsquot soluble in water as it needs I3- ions so instead it dissolves in Potassium iodide which is BrownIn organic solvents As halogens are non-polar they dissolve more easily in hydrocarbon solvents than water Chlorine= Pale yellow Bromine=Brown Iodine=Purple

Oxidisation reactions

Halogens are strong oxidising agents

With metals Form salts 2Fe+3Cl2 2FeCl3 Fe+I2 FeI2

With Hydrogen Decreasing reactivity down group Chlorine explodes whereas Bromine and Iodine need 300˚C and Platinum catalystWith Phosphorus Chorine forms a chloride (III) then a chloride (V)With Iron Chloride Green iron (II) chloride becomes oxidised to brown iron (III) chloride

Chlorine is a stronger oxidising agent than iodine 2KI-+Cl2 2KCl+I2

Sulphuric acid oxidises halides and halogens with increasing vigour down the group

Hydrogen Halides are covalent but become increasingly ionic as you go up the group

Hydrogen Halides and Ammonia NH3+HCl NH4Cl

Disproportionation reactions

With cold dilute Alkali Cl2+2OH- Cl-+ClO-+H2OWith warm Alkali 3ClO- 2Cl-+ClO3

-

Testing for halogens

Silver halides AgCl-White precipitate which is soluble in ammonia AgBr- Cream precipitate which is soluble in ammonia AgI- Yellow precipitate which is insoluble in ammonia

Concentrated sulphuric acid and glass rod with ammonia Chlorine=white fumes white smoke Bromine=white and orange fumes white smoke Iodine=White and purple fumes white smoke

26-Kinetics

Rate of reaction Speed with which reactants disappear and products are formed for a particular reaction

Decreased rate=Decreased yield

Factors in rate of reaction

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Disproportionation Where a substance is both oxidised and reduced in a reaction

Common Oxidising Agents Common Reducing agentsO2+4e- 2O2- M Mn++e- (metal)Cl2+2e- 2Cl- Fe2+ Fe3++e-

Br2+2e- 2Br- 2I- I2+2e-

I2+2e- 2I- 2S2O32- S4O6

2-+2e-

Fe3++e- Fe2+ C2O42- 2CO2+2e-

2H++2e- H2 H2O2 O2+2H++2e-

Mn04-+8e- Mn2++4H2O S03

2-+H2O SO42-+2H++2e-

Cr2O72-+14H++6e- 2Cr3++7H2O

2H2SO4+2e- SO42-+2H2O+SO2

25-Periodic Table

Group 2

Trend in 1st Ionisation energy Decreases down the group due to increasing atomic radius where the outer electrons are further away so less energy is needed to remove an electron Forms 2+ ions easily

Reactions- With Oxygen Burns brightly to produce a metal oxide with increasing reactivity down the groupWith Chlorine Solid metal chloride formed Also has an increase in reactivityWith Water Increasing reactivity down group Beryllium has no reaction Magnesium only reacts with steam to produce a magnesium oxide and the rest react with cold water to produce metal hydroxidesOxides with Water Increasing reactivity Beryllium and magnesium only react slightly Calcium fizzes to produce calcium hydroxide (slaking lime) and strontium and Barium react in a similar wayOxidesHydroxides with Dilute Acids Forms a salt and water Eg CaCl2+ H2O or Ca(NO3)2+H2O

Flame Testing Place nichrome wire in concentrated HCl then heat in a bunsen flame to clean Colours of flames are shown in table

Solubility

Of hydroxides Increases down groupOf Sulphates Decreases down groupThermal StabilityOf Nitrates Decreases down group 1 due to weaker charge of attraction Group 1 are more stable than group 2 apart from lithium due to larger charge 2NaNO3 2NaNO2+O2 4liNO3 2Li2O+4NO2+O2 2Mg(NO3)2 2MgO+4NO2+O2

Of Carbonates More stable as you go down the group as cations get bigger so there is a more polarising effect on the carbonate

Group7-Halogens

Cation Flame ColourLithium RedSodium YellowPotassium LilacMagnesium

No colour

Calcium OrangeRedStrontium RedBarium Pale Green

Solubility

In Water Chlorine forms chlorine water which is colourless Bromine water is Orange Iodine isnrsquot soluble in water as it needs I3- ions so instead it dissolves in Potassium iodide which is BrownIn organic solvents As halogens are non-polar they dissolve more easily in hydrocarbon solvents than water Chlorine= Pale yellow Bromine=Brown Iodine=Purple

Oxidisation reactions

Halogens are strong oxidising agents

With metals Form salts 2Fe+3Cl2 2FeCl3 Fe+I2 FeI2

With Hydrogen Decreasing reactivity down group Chlorine explodes whereas Bromine and Iodine need 300˚C and Platinum catalystWith Phosphorus Chorine forms a chloride (III) then a chloride (V)With Iron Chloride Green iron (II) chloride becomes oxidised to brown iron (III) chloride

Chlorine is a stronger oxidising agent than iodine 2KI-+Cl2 2KCl+I2

Sulphuric acid oxidises halides and halogens with increasing vigour down the group

Hydrogen Halides are covalent but become increasingly ionic as you go up the group

Hydrogen Halides and Ammonia NH3+HCl NH4Cl

Disproportionation reactions

With cold dilute Alkali Cl2+2OH- Cl-+ClO-+H2OWith warm Alkali 3ClO- 2Cl-+ClO3

-

Testing for halogens

Silver halides AgCl-White precipitate which is soluble in ammonia AgBr- Cream precipitate which is soluble in ammonia AgI- Yellow precipitate which is insoluble in ammonia

Concentrated sulphuric acid and glass rod with ammonia Chlorine=white fumes white smoke Bromine=white and orange fumes white smoke Iodine=White and purple fumes white smoke

26-Kinetics

Rate of reaction Speed with which reactants disappear and products are formed for a particular reaction

Decreased rate=Decreased yield

Factors in rate of reaction

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Solubility

In Water Chlorine forms chlorine water which is colourless Bromine water is Orange Iodine isnrsquot soluble in water as it needs I3- ions so instead it dissolves in Potassium iodide which is BrownIn organic solvents As halogens are non-polar they dissolve more easily in hydrocarbon solvents than water Chlorine= Pale yellow Bromine=Brown Iodine=Purple

Oxidisation reactions

Halogens are strong oxidising agents

With metals Form salts 2Fe+3Cl2 2FeCl3 Fe+I2 FeI2

With Hydrogen Decreasing reactivity down group Chlorine explodes whereas Bromine and Iodine need 300˚C and Platinum catalystWith Phosphorus Chorine forms a chloride (III) then a chloride (V)With Iron Chloride Green iron (II) chloride becomes oxidised to brown iron (III) chloride

Chlorine is a stronger oxidising agent than iodine 2KI-+Cl2 2KCl+I2

Sulphuric acid oxidises halides and halogens with increasing vigour down the group

Hydrogen Halides are covalent but become increasingly ionic as you go up the group

Hydrogen Halides and Ammonia NH3+HCl NH4Cl

Disproportionation reactions

With cold dilute Alkali Cl2+2OH- Cl-+ClO-+H2OWith warm Alkali 3ClO- 2Cl-+ClO3

-

Testing for halogens

Silver halides AgCl-White precipitate which is soluble in ammonia AgBr- Cream precipitate which is soluble in ammonia AgI- Yellow precipitate which is insoluble in ammonia

Concentrated sulphuric acid and glass rod with ammonia Chlorine=white fumes white smoke Bromine=white and orange fumes white smoke Iodine=White and purple fumes white smoke

26-Kinetics

Rate of reaction Speed with which reactants disappear and products are formed for a particular reaction

Decreased rate=Decreased yield

Factors in rate of reaction

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Concentration Affects number of collisions due to change in number of particles in a given volumeTemperature Affects activation energy due to faster moving particles with more successful collisionsPressure Affects number of collisions due to change in number of particles in a given volumeSurface area Affects the number of particles open to contactCatalysts Changes the rate of reaction without being used up or undergoing any permanent changes by lowering the activation energy through forming an activated complex Industrial processes rely on catalysts to save money energy and resources

Collision theory In order for a reaction to happen colliding particles need to be in the right orientation and have enough energy Rate of reaction depends on this

Maxwell-Boltzmann model- models the distribution of molecular energies so changes in concentration temperature or pressure can be calculated to predict the rate of reaction Eg As the temperature rises the graph flattens so there are a greater proportion of particles moving fast enough to overcome activation energy

Activation energy Minimum energy required for a reaction to take place

27-Chemical Equilibria

Dynamic Equilibria Two opposing processes that occur at the same rate so have constant macroscopic properties

Le Chateliers principle Whenever a system in dynamic equilibrium is disturbed it tends to respond in opposition to the disturbance in order to restore equilibriumIncrease in Temperature Moves in the endothermic directionIncrease in Pressure Moves to the side with the fewest number of molesIncrease in Reactants Moves to the other side as more products are formed Increase rate

Equilibria Reactions N2O4 2NO2 ICl+ICl2 ICl3

Haber Process Production of ammonia (Exothermic reaction) Atom economy= 100 as all reactants are used (Recycled)

28-Organic Chemistry

Alcohols

Functional group -OH (Methanol Ethanol Propan-1-ol)

Primary Alcohol 1 carbon attached to the carbon with the functional group on it Secondary Alcohol 2 carbons attachedTertiary alcohol 3 carbons attached

Combustion Produces carbon dioxide and waterReaction with sodium 2Na+2C2H5OH 2C2H5O-Na++H2 effervescence forms a white precipitate

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Reaction with PCl5 Reaction produces a chlorine haloalkane POCl3 and HCl gas (misty white fumes that turn damp blue litmus paper red)Oxidation using acidified potassium dichromate (toxic carcinogen) Primary alcohols when oxidised produce aldehydes then carboxylic acids if refluxed Secondary alcohols produce ketones which canrsquot be oxidised further Tertiary alcohols show no reaction

When making ethanoic acid add ethanol carefully to dichromate as it could evaporate if added quickly Fractional distillation is used to separate ethanoic acid from the waste product water

Distillation Apparatus

Reflux Apparatus

Halogenoalkanes

Functional group R-Cl R-Br R-I

Primary Haloalkanes 1 carbon attached to the carbon with the functional group Most reactive as nucleophiles are more attractedSecondary Haloalkanes 2 Carbons attachedTertiary Haloalkanes 3 Carbons attached

Structural isomers are very common in haloalkanes A change in halogen atom position makes a huge difference to the properties of the molecule

Halogens react faster in substitution reactions if the halogen is attached to a branched chain

Metal halides and concentrated sulphuric acid should not be used in the creation of a haloalkane as they are very reactive

Reaction with aqueous KOH Substitution reaction which creates an alcohol as OH- is attracted to the carbocation after breaking H-ClReaction with alcoholic KOH Elimination reaction which produces an alkene KOH attracts H+ by acting as a baseReaction with silver nitrate dissolved in water Ag+ ion reacts with the halogens to create insoluble products (See page 6-Silver halides)Reaction with alcoholic ammonia ammonia acts as a nucleophile which replaces the halogen atom in a halogenoalkane

Uses of halogenoalkanes

Anaesthetic To put patient in a deep sleep Chlorine= deep sleep Fluorine-Carbon bonds= stable molecule so less toxicFire retardants Used to be in fire extinguishers but is now in circuit boards fabrics and clothingRefrigerants Liquid that changes phase to keep things coolAlso used in Aerosol containers and Insecticides

29-Mechanisms

Addition Two or more substances react to form a single productElimination Small molecule removed from a larger molecule leaving a double bondCondensation Addition followed by elimination of H2O or HClSubstitution One atom or group of atoms replaced by another atom or group of atomsOxidation Process where electrons are lostReduction Process where electrons are gainedHydrolysis Splitting of a molecule by reaction with H2OPolymersiation Joining of small molecules together in a long chain

Homolytic fission When a bond is broken and both atoms take a single electron each and form two free radicalsHeterolytic fission When a bond is broken and both electrons only go to one atom creating a negative ion and a positive ion (Carbanion and carbocation)

Free radicals Has an unpaired electron so is extremely reactive and short lived Eg ∙Cl ∙CH3

Electrophile Atom attracted to an electron-rich centre Has a positive charge Eg H+ Br+

Nucleophile atom attracted to an electron-deficient centre Has a negative charge Eg NH3

- OH-

Classifying reagents gives clues to how a mechanism will take place

Bond polarity determines whether the centre will be electron-rich or electron-deficient

Nucleophillic substitution reaction HalogenoalkanesFree-radical substitution reaction Alkanes with a halogenElectrophilic addition reaction Alkenes with hydrogen or a halogen

Ozone layer Formed by O+O2 O3 This layer absorbs UV light from the sun but when cloud cover and chemicals build up the spring UV light hitting the clouds causes any CFCs in them to break up and create free radicals which break down the ozone layer into O2 molecules

210-Mass spectra and IR absorption

Mass spectra

Highest mz Value= Parent ionMost Abundant peak= Base peakPeaks are produced by the fragmentation of organic molecules

IR absorption

C-H Stretching=2820-3010O-H Stretching=Broad peak at 2500-3750N-H Stretching=3300-3500C=O Stretching=1680-1740C-X Stretching=500-1400

There is a change in functional groups when alcohol is oxidised to a carbonyl or carboxylic acid

Only molecules that change polarity when they vibrate can absorb IR radiation eg Greenhouse gases

Diatomic molecules canrsquot absorb IR

211-Green Chemistry

Bio-oil is made for fuel from pyrolysis (heating wheat without burning) Ethanol is produced from organic waste by converting sugars using bacteria or yeast Starch has lots of uses including adhesives paper bonding textile fibres shopping bags absorption paper drug and pesticide encapsulation and corrugated card

Catalysts enable a reaction to go under lower temperatures and pressures to save energy Catalysts need to be cheap very active and produce no by-productsMicrowave ovens can heat reactants more economically Continuous pulses of radiation heats up reactants Electric field occurs which rotates polar molecules and lines them up

Recycling glass and aluminium saves energy from having to make more Water as a waste product from a reaction in a factory must be treated before being disposed to avoid contaminating the environment Waste acidic gases are removed from the rest of the air before it goes into atmosphere

CO2 is the most worrying greenhouse gas as it absorbs lots of IR and is abundant in the atmosphere The other greenhouse gases arenrsquot as abundant

Athropogenic factors due to activities of human beingsNatural factors due to natural processes on earth

Carbon neutral a process that gives out as much CO2 as it takes in

Carbon footprint a measure of the impact on environment from how much greenhouse gas is produced (Measured in CO2)

Petrol isnrsquot carbon neutral due to the slow process of formation of crude oilBio-ethanol isnrsquot carbon neutral either as production of biofuel requires energyHydrogen isnrsquot carbon neutral as it creates CO2 when it is being formed from methanol

Cl˙+O3 ClO˙+O2

ClO˙+O3 Cl˙+2O2

So in total 2O3 3O2 due to CFCs so more UV radiation therefore hits earth

Titration calculations

To find percentage of a metal in an impure substance1 Find the no of moles using the known concentration and volume of a

substance2 Use the molar ratio to find the no of moles in the other reacting

substance with the metal3 If divided by 10 fold in question x no of moles by 10 to get original no

of moles4 Original no of moles x Mr of metal= Mass of metal in grams5 Mass of metalTotal mass x100= Percentage of metal

Ozone layer Formed by O+O2 O3 This layer absorbs UV light from the sun but when cloud cover and chemicals build up the spring UV light hitting the clouds causes any CFCs in them to break up and create free radicals which break down the ozone layer into O2 molecules

210-Mass spectra and IR absorption

Mass spectra

Highest mz Value= Parent ionMost Abundant peak= Base peakPeaks are produced by the fragmentation of organic molecules

IR absorption

C-H Stretching=2820-3010O-H Stretching=Broad peak at 2500-3750N-H Stretching=3300-3500C=O Stretching=1680-1740C-X Stretching=500-1400

There is a change in functional groups when alcohol is oxidised to a carbonyl or carboxylic acid

Only molecules that change polarity when they vibrate can absorb IR radiation eg Greenhouse gases

Diatomic molecules canrsquot absorb IR

211-Green Chemistry

Bio-oil is made for fuel from pyrolysis (heating wheat without burning) Ethanol is produced from organic waste by converting sugars using bacteria or yeast Starch has lots of uses including adhesives paper bonding textile fibres shopping bags absorption paper drug and pesticide encapsulation and corrugated card

Catalysts enable a reaction to go under lower temperatures and pressures to save energy Catalysts need to be cheap very active and produce no by-productsMicrowave ovens can heat reactants more economically Continuous pulses of radiation heats up reactants Electric field occurs which rotates polar molecules and lines them up

Recycling glass and aluminium saves energy from having to make more Water as a waste product from a reaction in a factory must be treated before being disposed to avoid contaminating the environment Waste acidic gases are removed from the rest of the air before it goes into atmosphere

CO2 is the most worrying greenhouse gas as it absorbs lots of IR and is abundant in the atmosphere The other greenhouse gases arenrsquot as abundant

Athropogenic factors due to activities of human beingsNatural factors due to natural processes on earth

Carbon neutral a process that gives out as much CO2 as it takes in

Carbon footprint a measure of the impact on environment from how much greenhouse gas is produced (Measured in CO2)

Petrol isnrsquot carbon neutral due to the slow process of formation of crude oilBio-ethanol isnrsquot carbon neutral either as production of biofuel requires energyHydrogen isnrsquot carbon neutral as it creates CO2 when it is being formed from methanol

Cl˙+O3 ClO˙+O2

ClO˙+O3 Cl˙+2O2

So in total 2O3 3O2 due to CFCs so more UV radiation therefore hits earth

Titration calculations

To find percentage of a metal in an impure substance1 Find the no of moles using the known concentration and volume of a

substance2 Use the molar ratio to find the no of moles in the other reacting

substance with the metal3 If divided by 10 fold in question x no of moles by 10 to get original no

of moles4 Original no of moles x Mr of metal= Mass of metal in grams5 Mass of metalTotal mass x100= Percentage of metal

Carbon footprint a measure of the impact on environment from how much greenhouse gas is produced (Measured in CO2)

Petrol isnrsquot carbon neutral due to the slow process of formation of crude oilBio-ethanol isnrsquot carbon neutral either as production of biofuel requires energyHydrogen isnrsquot carbon neutral as it creates CO2 when it is being formed from methanol

Cl˙+O3 ClO˙+O2

ClO˙+O3 Cl˙+2O2

So in total 2O3 3O2 due to CFCs so more UV radiation therefore hits earth

Titration calculations

To find percentage of a metal in an impure substance1 Find the no of moles using the known concentration and volume of a

substance2 Use the molar ratio to find the no of moles in the other reacting

substance with the metal3 If divided by 10 fold in question x no of moles by 10 to get original no

of moles4 Original no of moles x Mr of metal= Mass of metal in grams5 Mass of metalTotal mass x100= Percentage of metal