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AG Definitions. AG Energy level is the fixed energy value that an electron in an atom may have. Exam Q (Hons) ‘08/Q10c ‘07/Q4.

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Presentation on theme: "AG Definitions. AG Energy level is the fixed energy value that an electron in an atom may have. Exam Q (Hons) ‘08/Q10c ‘07/Q4."— Presentation transcript:

1 AG Definitions

2 AG Energy level is the fixed energy value that an electron in an atom may have. Exam Q (Hons) ‘08/Q10c ‘07/Q4

3 AG Ground State lowest energy state ( in 1s orbital) Excited state = higher energy state Exam Q (Hons) 08/Q10c

4 AG An orbital is a region in space within which there is a high probability of finding an electron. Exam Q (Hons) ‘06/Q5

5 AG An element is a substance that cannot be split up into simpler substances by chemical means.

6 AG A triad is a group of three elements with similar chemical properties in which the atomic weight of the middle element is approximately equal to the average of the other two. (Dobereiner)

7 AG Newlands’ Octaves are groups of elements arranged in order of increasing atomic weight, in which the first and the eighth element of each group have similar properties.

8 AG Mendeleev’s Periodic Law When elements are arranged in order of increasing atomic weight (relative atomic mass), the properties of the elements vary periodically.

9 AG The atomic number(Z) is the number of protons in the nucleus of that atom.

10 AG Periodic Table is an arrangement of elements in order of increasing atomic number.

11 AG Elements are arranged in order of increasing atomic number, the properties of the elements vary periodically.

12 AG Mass number (A) is the sum of the number of protons and neutrons in the nucleus of an atom of that element.

13 AG Isotopes are atoms of the same element ( i.e. they have the same atomic number) that have different mass numbers due to the different number of neutrons in the nucleus. Exam Q (Hons) ’06/Q10a

14 AG Relative Atomic Mass is the average of the mass numbers of the isotopes of the element as they occur naturally taking their abundances into account relative to 1/12 th mass of carbon 12 atom (expressed on a scale in which the atoms of carbon 12 isotope have a mass of exactly 12 units). Exam Q (Hons) ’06/Q10a

15 AG Mass Spec. V I A S D Victor A+  Vaporisation Ionisation Acceleration Separation Detection how? why?

16 AG Aufbau Principle that when building up the electronic configuration of an atom in its ground state, the electrons occupy the lowest available energy level.

17 AG Hund’s Rule of Maximum Multiplicity states that when two or more orbitals of equal energy are available, the electrons occupy them singly first before filling them in pairs.

18 AG Pauli Exclusion Principle that no more than two electrons may occupy an orbital and they must have opposite spins.

19 AG Compound is a substance that is made up of two or more different elements combined together chemically.

20 AG Octet Rule that when bonding occurs, atoms tend to reach an electron arrangement with eight electrons in the outermost shell.

21 AG An Ion is a charged atom or group of atoms.

22 AG An Ionic bond is the force of attraction between oppositely charged ions in a compound.

23 AG A transition metal is one that forms at least one ion with a partially filled d sublevel.

24 AG Molecule is a group of atoms joined together. It is the smallest particle of an element or compound that can exist independently.

25 AG Valency of an element is defined as the number of atoms of hydrogen or any other monovalent element with which each atom of the element combines.

26 AG Electronegativity is a measure of the relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond. Exam Q (Hons) ’06/Q5

27 AG Electronegativity difference > 1.7 indicates ionic bonding in a compound. An electronegativity difference ≤ 1.7 indicates covalent bonding in a compound.

28 AG The value of electronegativity decrease down the groups in the Periodic Table for two reasons: increasing atomic radius screening effect of inner electrons

29 AG The values of electronegativity increase across the periods in the Periodic Table for two reasons: increasing nuclear charge decreasing atomic radius F= most electronegative element. Halogens –decrease in reducing power down the group due to drop in electroneg. values.

30 AG Intermolecular Forces attractive (repulsive) forces between molecules Intramolecular forces are attractive (repulsive) forces within a molecule

31 AG Vans der Waals Forces are weak attractive forces between molecules resulting from the formation of temporary dipoles.

32 AG Dipole-dipole Dipole – dipole forces are forces of attraction between the negative pole of one molecule and the positive pole of another.

33 AG Hydrogen bonds are particular types of dipole-dipole attractions between molecules in which hydrogen atoms are bonded to nitrogen, oxygen or fluorine. The hydrogen atom carries a partial positive charge and is attracted to the electronegative atom in another molecule. Thus, H acts as a bridge between two electronegative atoms.

34 AG The Law of Conservation of Mass the total mass of the products of a chemical reaction is the same as the total mass of the reactants.

35 AG The Law of Conservation of Matter that in any chemical reaction, matter is neither created nor destroyed but merely changes from one form into another.

36 AG Tests for Anions Chloride Sulfate/sulfite carbonate/hydrogen carbonate nitrate phosphate (NB know confirmatory test too!)

37 AG Chloride Add AgNO 3 Get white ppt Confirm = ppt dissolves in dilute ammonia Equation needed

38 AG Sulfate/sulfite Add BaCl 2 Get white ppt Distinguish add dil HCl to white ppt ppt remains = sulfate ppt dissolves = sulfite Equation needed !!

39 AG CO 3 2- /HCO 3 - Add dil. HCl (or any acid) Get bubbles of CO 2 (limewater milky) Distinguish add MgSO 4 to fresh solution Get white ppt. immediately = carbonate white ppt on heating = hydrogen carbonate Equation needed !!

40 AG Nitrate Brown Ring Test Add fresh FeSO 4 At slant add conc. H 2 SO 4 drop wise Get brown ring at junction of 2 layers No equation needed

41 AG Phosphate Add ammonium molybdate Add 5 drops of conc. nitric acid (warm the solution) Get yellow ppt No equation needed Confirm: Goes colourless when add dilute NH 3

42 AG The atomic radius of an atom is defined as half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond. Exam Q (Hons) 07/Q4

43 AG The values of atomic radius increase down any one group in the Periodic Table for two reasons: extra shell screening effect of inner electrons

44 AG The values of atomic radius decrease from left to right across a Periodic Table for two reasons: increasing nuclear charge no increase in screening effect

45 AG The first ionisation energy of an atom is the minimum energy required to completely remove the most loosely bound electron from one mole of neutral gaseous atom in the ground state.****** 2004 =9 marks (2.25%) 2002 = 8marks(2%)

46 AG The values of ionisation energy decrease down the groups in the Periodic Table for two reasons: increasing atomic radius screening effect of inner electrons

47 AG The values of ionisation energy increase across the Periodic Table for two reasons: increasing nuclear charge decreasing atomic radius

48 AG More on ionisation energy First Ionisation Energy M – e -  M + Second Ionisation energy M + – e -  M 2+ Major jump in I.E. values – significance

49 AG The value of electronegativity decrease down the groups in the Periodic Table for two reasons: increasing atomic radius screening effect of inner electrons

50 AG The values of electronegativity increase across the periods in the Periodic Table for two reasons: increasing nuclear charge decreasing atomic radius F= most electronegative element. Halogens –decrease in reducing power down the group due to drop in electroneg. values.

51 AG A gas is a substance that has no well-defined boundaries but diffuses rapidly to fill any container in which it is placed.

52 AG Radioactivity is the spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation.

53 AG Alpha particles loss of He nucleus (2p + 2n) mass number down by 4 atomic number down by 2 element changes to element two places back

54 AG Beta particle neutron changes to proton and electron electron emitted mass number stays same atomic number drops by one element changes into element one place back

55 AG Gamma radiation no new atoms formed (no transmutation) only energy lost

56 AG Half Life of an element is the time taken for half the nuclei in any given sample to decay.

57 AG Mole is the amount of a substance which contains 6 X 10 23 particles of that substance (avogadro’s number or constant =L)

58 AG a few numbers Kelvin = Celsius + 273 standard temp = 273 K standard pressure = 1X10 5 Pa (100kPa) m 3 = litres X10 -3 m 3 = cm 3 X10 -6 (1 litre = 1000cm 3)

59 AG Mole contains 6 X 10 23 particles has mass equal to Ar or Mr in grams occupies 22.4 litres at s.t.p (if gas)

60 AG Boyle’s Law states that: at constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

61 AG Charles’ Law states that: at constant pressure, the volume of a fixed mass of a gas is directly proportional to its temperature measured on the Kelvin scale.

62 AG General Gas Law P 1 X V 1 = P 2 X V 2 T1T2T1T2 Temp in Kelvin Units for volume same each side Units for pressure same each side

63 AG Gay Lussac’s law of Combining Volumes the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers provided the volumes are measured at the same temp and pressure

64 AG Avogadro’s Law states that equal volumes of gases contain equal numbers of molecules under the same conditions of temp. and pressure Exam Q (Hons) ‘07/Q10b

65 AG Molar Volume At s.t.p one mole of any gas occupies 22.4 litres Remember to watch out for r.t.p in questions room temp. and press = as given in Q (often 24 litres)

66 AG Ideal Gas is one which perfectly obeys all the gas laws and all the assumptions* of the kinetic theory of gases under all conditions of temperature and pressure. (Know the assumptions) Exam Q (Hons) ’06/Q11a

67 AG Real v. ideal gas Real gases differ from ideal gases at high pressure and low temp. because there are forces of attraction/repulsion between the molecules* the volume of the molecules is not negligible compared to the distances between them (*know examples of real gases and the forces involved)

68 AG Empirical Formula gives the simplest whole number ratio of the numbers of the different atoms present in the molecule. (divide by Ar and get ratio) (molecular formula is a simple multiple of the empirical formula)

69 AG Acids / Bases Arrhenius Acid + Base Bronsted Lowry Acid + Base Neutralisation Conjugate Acid/ conjugate base conjugate pair

70 AG Arrhenius Acid and Base Arrhenius Acid is a substance that dissociates in water to produce H+ ions. Arrhenius Base is a substance that dissociates in water to produce OH - ions.

71 AG Bronsted Lowry Acid /Base Bronsted Lowry Acid is a proton (H+) donor Bronsted Lowry Base is a proton (H+) acceptor Exam Q (Hons) ’07/Q7

72 AG Neutralisation is the reaction between an acid and a base forming a salt and water (acid + base -> salt + water) SALT = is formed when the H of an acid is replaced by a metal

73 AG Conjugate Acid / Conjugate Base Conjugate Acid is formed when a base accepts a proton Conjugate Base is formed when an acid donates a proton.

74 AG Conjugate Pair an acid and a base that differ by a proton Exam Q (Hons) ‘07/Q7

75 AG Primary Standard is a substance of high Mr which can be obtained in a pure stable soluble solid form so that it can be weighed out and dissolved in water to give a solution of accurately known concentration. (Know why high Mr matters)

76 AG Titration is a laboratory procedure where a a measured volume of one solution is added to a known volume of another solution until the reaction is complete. (concentration of one solution known accurately at start) (indicator used to show by colour change when reaction is complete)

77 AG Oxidation Reduction Revision

78 AG Definitions Oxidation is addition of loss of increase in oxygen electrons oxidation number Exam Q (Hons) ‘08/Q10(b) ’06/Q10(b)

79 AG Reduction is loss of oxygen gain of electrons decrease in oxidation number

80 AG More… An oxidising agent causes oxidation and is itself reduced. A reducing agent causes reduction and is itself oxidised. What is a redox reaction?

81 AG What is oxidised and reduced in each of the following? Br 2 + 2Fe 2+ → 2Br – + 2Fe 3+ Cu 2+ + Zn  Cu + Zn 2+ 2Na + Cl 2  2NaCl

82 AG Oxidation Number Rules The oxidation number of an Element is 0 group One elements is +1 group Two elements is +2 in compounds

83 AG The oxidation number of an ion is equal to the charge on the ion halogens is -1 (in binary compounds) (except ……????)

84 AG The oxidation number of H in a compound is +1 –except in metal hydrides when it is -1

85 AG The oxidation number of O in a compound is -2 –except (x2) in peroxides when it is -1 (H 2 O 2 ) in OF 2 when it is +2 (why?)

86 AG Oxidation numbers add up to zero in a compound add up to the charge of a complex ion

87 AG What is the oxidation number of each element in :- H20H20 MnO 4 ¯ I2I2 KBrO 3 Na 2 S 2 O 3 H2O2H2O2 NaClO

88 AG KMnO 4 oxidising agent purple read top of meniscus is reduced from Mn (VII)  Mn (II) in presence of H + purple  colourless own indicator (end point = first permanent pink)

89 AG KMnO 4 get brown Mn (IV) if H + absent (which acid MUST be used – why x2) not primary standard (x2) standardised by titrating against standard solution of acidified Fe 2+

90 AG H 2 SO 4 added during KMnO 4 titrations to provide H + and ensure the complete reduction of Mn (VII)  Mn (II) and prevent formation of Mn (IV) (brown) added during prep. of Fe (II) solutions to prevent oxidation of Fe 2+ to Fe 3+ by oxygen in the air ( why does this matter?)

91 AG Na 2 S 2 O 3 S 2 O 3 2- ion reducing agent used in photography not primary standard – why ? standardised by titrating against I 2 starch indicator – when added and why colour change at end point ?

92 AG IodineI 2 Oxidising agent NOT a primary standard (X2) Produced when MnO 4 - oxidises I - to I 2 »(known concentration)(in excess) Starch indicator – when added? why then? Colour change at end point Blue/black to colourless

93 AG Bleach sodium hypochlorite Na + ClO - bleach diluted x10 with distilled water not de-ionised water (why? ) ClO - oxidises I - to I 2 I 2 v. thiosulfate starch indicator as before NB remember dilution factor in calculations

94 AG Definitions Rate of reactions

95 AG Rates of Reactions The rate of reaction is the change in concentration per unit time of any one reactant or product. Exam Q (Hons) 2003 Q7 2004 Q8 2007/Q9 2011 /Q5

96 AG Factors affecting rate nature of reactants particle size concentration temperature catalysts

97 AG Equations to know Write each equation then check Decomposition of hydrogen peroxide using manganese dioxide as catalyst MnO 2 2H 2 O 2  2H 2 O + O 2 Sodium thiosulfate and hydrochloric acid Na 2 S 2 O 7 + 2HCl  S  + 2NaCl + SO 2 +H 2 O

98 AG Rate Graphs Concentration v. ( 1 /Time ) or Temp v. ( 1 /Time ) ( 1 /Time )used as Rate and Time inversely related (shorter time means faster rate) be careful with units of 1/time

99 AG Catalyst is a substance that alters the rate of reaction but is not consumed in the reaction. Exam Q (Hons) 2003 Q7 ‘07/Q9

100 AG Homogeneous catalysis occurs when the reactants and the catalyst are in the same phase. example =? liquids KI catalyses 2H 2 O 2  2H 2 O + O 2 (iodine snake) And any enzyme

101 AG Heterogeneous catalysis occurs when the reactants and the catalyst are in different phases. (NB must be phases not states) example = ? Al 2 O 3 (solid) catalyses ethanol (gas)  ethene Exam Q (Hons) ‘07/Q4 Methanol  methanal using platinum

102 AG Autocatalysis occurs when one of the products of the reaction catalyses the reaction. Example = ? Mn 2+ ions in KMnO 4 titrations (purple changes to colourless more quickly as titration proceeds)

103 AG Mechanism of Catalysis Intermediate Formation theory Surface Adsorption theory Know details of each and evidence of intermediate formation theory

104 AG Enzymes Are biological catalysts made of protein Examples of homogeneous catalysis Need to know 2 examples –Amylase catalyses conversion of starch to maltose –Catalase catalyses conversion of hydrogen peroxide to hydrogen and water

105 AG Learning Check Do I know Definition for 1.Rate of reaction 2.Catalyst 3.Homogeneous catalysis 4.Heterogeneous catalysis 5.Auto catalysis 6.Two mechanisms of catalysis Press enter to continue

106 AG Catalytic converter Catalysts = ? Pt + Pd + Rh on honeycomb surface (ceramic) Gases in CO NO NO 2 hydrocarbons Gases out CO 2 and N 2 and H 2 0

107 AG Learning Check Do I know 1.3 metals in Catalytic converter 2.4 wastes in exhaust fumes 3.Problem of each 4.What each is converted to 5.What poisons catalytic converter 6.Type of catalysis occuring in catalytic converter Press enter to continue

108 AG Collision Theory for a reaction to occur the reacting particles must collide with each other a collision only results in a product being formed if a certain minimum energy is exceeded (called activation energy)

109 AG Effective Collision Is one in which a reaction occurs The activation energy has been reached or exceeded. Exam Q (Hons) 2009 Q9

110 AG Activation Energy is the minimum energy which colliding particles must have for a reaction to occur (minimum energy required for effective collisions between particles) Exam Q (Hons) 2006/Q7 2009/Q9

111 AG Activation Energy 2 Catalysts lower the activation energy of a reaction Without catalyst with catalyst Compare E act

112 AG Energy Profile Diagram Sketch an energy profile diagram for an endothermic reaction. Press enter when ready and It should look like this

113 AG Endothermic Energy Profile Diagram Reactants Products Energy In Activation Energy Note – axes should be labelled Time (x) and energy (y) Curve should be smooth !

114 AG Energy Profile Diagram Sketch an energy profile diagram for an exothermic reaction. Press enter when ready and It should look like this

115 AG Exothermic Energy Profile Diagram Reactants Products Energy Out Activation Energy Note – axes should be labelled Time (x) and energy (y) Curve should be smooth !

116 AG Learning Check Do I know Definition for 1.Effective collision 2.Activation energy Can I draw energy profile diagram for 1.Exothermic reaction 2.Endothermic reaction 3.Either of above with catalyst The End

117 AG Chemical Equilibrium is a state of dynamic balance where the rate of the forward reaction equals the rate of the reverse reaction.

118 AG Le Chatelier’s Principle If a stress is applied to a system at equilibrium the system readjusts to oppose the stress applied reactions at equilibrium // oppose the applied stress(es)* Exam Q (Hons) ’06/Q11b

119 AG Le Chatelier’s Principle and Gases Le Chatelier’s Principle predicts that in an all-gaseous reaction an increase in pressure will favour the reaction which takes place with a reduction in volume ( towards the side with the smaller number of molecules)

120 AG Equilibrium Constant Kc [ ] means concentration in moles per litre [ C] c x [D] d Kc = -----------------for aA + bB  cC + dD [A] a x [B] b (product of products conc. over product of reactants conc.)

121 AG Le Chatelier and Industry Ammonia and Haber Process predict max yield at high press. /low temp reality = 200 atm and 500 o C Sulfuric Acid and Contact Process predict max yield at high press. /low temp reality = one atm and 450 o C

122 AG Kc large Kc => equilibrium far to right (lots of product produced) small Kc => equilibrium far to left (v. little product formed) must quote temp. units – depend on reaction tells us how far not how fast a reaction occurs

123 AG pH pH = -log [H + ] pH < 7 acid pH = 7 neutral pH > 7 base [ ] = moles per litre

124 AG KwKw Kw = [H + ].[OH - ] ([H + ] = √ K w ) Also remember Kw = 1x10 -14 ( at 25 o C) so [H + ]= 1x10 -7 and pH =7 Exam Q (Hons) 08/Q8

125 AG Strong / Weak acid A strong acid is a good proton donor or (is fully dissociated into ions in dilute aqueous soln. [H + ] = [acid] HCl [H + ] = 2x[acid] H 2 SO 4 etc A weak acid is a poor proton donor or (slightly dissociated into ions in dil. aq. soln.) [H + ] = √Ka x Macid Exam Q (Hons) ‘07/Q7

126 AG Strong / Weak base A strong base is a good proton acceptor or one which is fully dissociated into ions in dilute aqueous solution [OH - ] = [base] NaOH [OH - ] = 2x[base] Ca(OH) 2 etc A weak base is a poor proton acceptor or one which is slightly dissociated in dli. aq. soln. [OH-] = √K b x M base

127 AG Indicator An acid base indicator is a substance that changes colour according to the pH of the solution it is in. (equilibrium HIn ↔ H + + In -)

128 AG Methyl orange in acid (lower pH ) red in base ( higher pH) yellow range pH3-5

129 AG Phenolphthalein in acid (lower pH ) colourless in base ( higher pH) pink range pH8-11

130 AG Litmus in acid (lower pH ) red in base ( higher pH) blue range pH5-8 (Not as reliable as others for accurate work)

131 AG Which indicator ? strong acid/strong base = methyl orange / phenolphthalein /litmus ( see above) strong acid / weak base = methyl orange weak acid /strong base = phenolphthalein weak acid / weak base = none (why?)

132 AG Hard Water is water that will not easily form a lather with soap due to the presence of Ca 2+ or Mg 2+ ions in solution. Exam Q (Hons) ’06/Q8

133 AG Temporary Hardness can be removed by boiling the water due to Ca(HCO 3 ) 2 becomes CaCO 3 on heating leads to blocked pipes etc

134 AG Permanent Hardness is not removed by boiling the water caused by CaSO 4 or MgSO 4

135 AG Methods of removing hardness boiling (only works for temp. hardness) distillation washing soda ion exchange

136 AG Calculations Total hardness = calcium hardness + magnesium hardness but Do calculations as if all hardness caused by CaCO 3 expressed in p.p.m of CaCO 3 p.p.m. = mg/litre

137 AG Water Treatment screening flocculation sedimentation filtration chlorination fluoridation pH adjustment

138 AG B.O.D Biochemical Oxygen Demand is the amount of dissolved oxygen consumed by biological action when a sample of water is kept at 20 o C in the dark for five days. (know reason for each of 3 conditions)

139 AG Eutrophication is the enrichment of water with nutrients which leads to the excessive growth of algae. Nutrients – phosphates/nitrates Algal bloom / oxygen depletion

140 AG Sewage Treatment Primary Treatment physical Secondary Treatment biological Tertiary Treatment chemical

141 AG Water Analysis Atomic Absorption Spectrometry used to detect heavy metals like Cd, Hg, Pb pH meter colorimetry (Hach test Chlorine in pool water)

142 AG Electrolysis is the use of electricity to bring about a chemical reaction. KI/ Acidified water/ Na 2 SO 4 /CuSO 4 / ions

143 AG Electrolyte is a substance that conducts electricity as a result of the presence of ions.

144 AG Electroplating is the process where electrolysis is used to put a layer of one metal on the surface of another.

145 AG Electrochemical Series is a list of the elements in order of their standard electrode potentials.

146 AG Organic Chemistry is the study of compounds of carbon… (except some simple compounds like CO 2, CO and carbonates)

147 AG Hydrocarbon is a compound that contains only carbon and hydrogen includes alkanes, alkenes, alkynes excludes alcohols, aldehydes, ketones, carboxylic acids, esters

148 AG Saturated compound is one with only carbon – carbon single bonds alkanes

149 AG Unsaturated compound is one which contains at least one carbon – carbon double or triple bond and undergoes addition reactions alkenes / alkynes test for unsaturation decolourise bromine solution Exam Q (Hons) 08/Q9

150 AG Homologous Series is a series of chemical compounds of uniform chemical type showing gradations in physical properties having a general formula for its members each member has similar method of prep. and each member differs by (CH 2 ) from previous member

151 AG Structural isomers are compounds with the same molecular formula but different structural formulas. e.g. butane and methyl propane are both C 4 H 10 need to know isomers up to C 5 H 12

152 AG Aliphatic an aliphatic compound is an organic compound that consists of straight (open) chains of carbon atoms and closed chain compounds with similar properties.

153 AG Aromatic An aromatic compound is an organic compound that contains a benzene ring structure in their molecules. (benzene – delocalised double bond) (disc. by Michael Faraday ) (structure by Kekule)

154 AG Octane Number of a fuel is a measure of the tendency of the fuel to resist knocking. (Best fuels = high octane number = 100 = 2,2,4 tri methyl pentane) (Short chains, more branched chains, ring structures) (Worst fuels = low octane number =0 = heptane) Exam Q (Hons) ‘08/Q6 ’06/Q6

155 AG Ways to increase octane number isomerisation catalytic cracking dehydro-cyclis-ation (re-forming) add oxygenates

156 AG Isomerisation changing straight chain alkanes into branched chain alkanes

157 AG Catalytic cracking is the breaking down of long chain hydro- carbon molecules into short chain molecules by heat and catalysts (for which there is a greater demand) Exam Q (Hons) ‘07/Q6

158 AG Dehydrocyclisation ( Re-forming) involves the use of catalysts to form ring structures straight chain alkanes changed to cycloalkanes cycloalkanes changed to aromatic compounds petrol contains benzene = carcinogen health concerns

159 AG Adding Oxygenates addition of methanol ethanol MTBE to petrol to increase the octane number. (Methyl Tertiary Butyl Ether or 2 methoxy 2 methyl propane)

160 AG Exothermic reaction is one which produces heat. ∆ H is minus ( giving away)

161 AG Endothermic reaction is one which takes in heat. ∆ H is positive (add in) ammonium nitrate dissolving in water

162 AG Heat of Reaction is the heat change involved when the numbers of moles of reactants indicated in the balanced equation for the reaction react completely.

163 AG Heat of Combustion is the heat change involved when one mole of a substance is completely burned in excess oxygen

164 AG Kilogram Calorific Value of a fuel is the heat energy produced when 1 kg of a fuel is completely burned in oxygen.

165 AG Bond Energy is the energy required to break one mole of covalent bonds and to separate the neutral atoms completely from each other.

166 AG Heat of Neutralisation is the heat change involved when one mole of H + ions from an acid reacts with one mole of OH - from a base forming one mole of H 2 O

167 AG Heat liberated Heat liberated = M x C x Rise in temp. Kgkelvin M=Mass of solution in Kg c=specific heat capacity rise in temp in Kelvin

168 AG Heat of formation of a compound is the heat change involved when one mole of a compound in its standard state is formed from its elements in their standard states.

169 AG Hess’s Law states that if a chemical reaction takes place in a number of stages, the sum of the heat changes in the separate stages is equal to the heat change if the reaction is carried out in one stage. (overall heat change is independent of the pathway)

170 AG Law of Conservation of Energy states that energy cannot be created or destroyed but can be changed from one form of energy to another.

171 AG Functional Group is an atom or group of atoms which is responsible for the characteristic properties of a series of organic compounds.

172 AG Substitution Reaction is a chemical reaction in which an atom or group of atoms in a molecule is replaced by another atom or group of atoms mechanism = free radical substitution initiation (homolytic fission) propagation termination

173 AG Addition Reaction is a chemical reaction is which two substances react together forming a single substance. Mechanism = Ionic addition Approach/ polarisation / heterolytic fission /carbonium ion / product formation only happens to unsaturated compounds

174 AG Polymers are long chain molecules made by joining together many small molecules called monomers.

175 AG Elimination reaction is one in which a small molecule is removed from a larger molecule to leave a double bond in the larger molecule.

176 AG Organic Synthesis is the process of making organic compounds from simpler starting materials.

177 AG Chromatography is a separation technique in which a mobile phase carrying a mixture moves in contact with a selectively adsorbent stationary phase.

178 AG Instrumentation Mass Spec. AAS GC HPLC IR spec. UV spec. X ray crystallography (option 2)

179 AG Mass Spec. Positively charged ions are separated according to different relative masses when moving through magnetic field Victor A+  Vapourisation Ionisation Acceleration Separation Detection Used to Analyse blood of race horses for drugs Identify substances PrinciplesProcesses

180 AG Atomic Absorption Spectrometry Ground state atoms of an element absorb light characteristic of that element. Absorption is directly proportional to concentration. (higher absorbance means higher concentration of THAT ELEMENT present) Dissolve Atomise Absorb Measure Detection Used to analyse water samples for heavy metals Cd Hg Pb PrinciplesProcesses

181 AG Gas Chromatography GC Different components have different tendencies to dissolve in a non- volatile liquid, which is coated on fine particles of a solid in a the GC column Injection … Transport … Separation … Detection... Used with MS in drug testing also blood alcohol levels PrinciplesProcesses mobile phase ? stationary phase? ?

182 AG HPLC High Performance Liquid Chromatography Different components of a mixture have different tendencies to adsorb onto fine particles of solid in HPLC column PrinciplesProcesses Injection … Transport … Separation … Detection … Used to separate less volatile mixtures e.g. growth promoters in meat. mobile phase ? stationary phase? ?

183 AG IR Infra red spectrometry Molecules of a substance absorb infra –red of different frequencies. (different number/ type bonds) The combination of frequencies absorbed is unique to the molecules of each substance Prepare … Transmit IR Absorption… Detection… Spectrum obtained Used to identify functional groups and identify drugs PrinciplesProcesses

184 AG UV Ultra violet spectrometry Molecules absorb UV radiation Electrons promoted from ground state to higher energy states. Absorption is directly proportional to concentration. Prepare Transmit UV through Blank (o%abs) Sample (known + unknown) Spectrum obtained Quantatative used to find amount of org. subs. e.g. drugs PrinciplesProcesses

185 AG X ray crystallography Wavelengths of Xrays are comparable to distance between atoms in a crystal Xrays are scattered when they hit a crystal surface Pattern detected is analysed and structure worked out Prepare …. Transmit : x-ray detected on film Pattern analysed and structure worked out Used to determine structure of macro- molecules e.g. DNA Principles Processes


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