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Born Haber Cycle - Edexcel A Level

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Published in: Chemistry
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Handwritten note on Born haber cycle - under Enegetics Useful for A level Chemistry ( For all boards like AQA, Edexcel and CAIE)

Muhammed S / Abu Dhabi

12 years of teaching experience

Qualification: Post Graduate in Chemistry

Teaches: Chemistry, NEET, IIT JEE, Physics, Science, Home Science

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  1. o ca- CO S co-n eases DARA-A VV-OAXS Spontaneous process is any process which happen by itself without any external itervention. k.k-e- Q.k.va_R Change in entropy should be postive always for reaction to happen.
  2. H20(g) 02 cc C02 table A ENTROPY K-1 mol-I 1887 130.6 205.0 191.6 165.0 213.6 192.3 LIQUID CHsCH20H ENTROPY mol-I 69.9 239.7 160.7 172.8 SOLID H20(s) C(diamond) C(graphite) CaO caCOA FNTROPY : t •e-l mol-I 47.9 2.4 39.7 92.9 Use the values in table A to calcu CaC03(s) GO(s) + use the values In table A to calculate N2(g) + system for the following reaction: for the following reaction: using the Information un table A, calculate the Iola. entropy change at 298 K for the following reaction. — z t C x 1000 2_ -Z) O • 4 86
  3. CH4(g) + 202(g) -+ C02(g) + 2H20(1) AH = —890.3 kJ mol-I = +2.95 k.J mol-I This reaction will not takes place spontaneosuly at room temperature - Kinetically stable. Once the ignition is given to methane then the combustion reaction takes place - it is therm odynamically unstable. COS Sv-txlou- Use the data provided to calculate the total standard entropy change, AS at 298 K. for the following reaction: 2Fe(s) + -822kJ mol-I 272] K-l mol-I 205.0J mol- 90.0] K-l mol-I so so GASO
  4. 20 Nitrous oxide, N20, decomposes at high temperature to form nitrogen and oxygen. N20(g) N2@) + h02(g) (a) (i) Some standard molecular entropy data are shown. Substance nitrogen, oxygen, 02 nitrous oxide, N20 Standard molecular entropy / 1K' mori 192 Calculate the standard entropy change Of the system for the decomposition shown. Include a sign and units in your answer. (ii) The standard enthalpy change of the forward reaction is —820nol•l. Calculate the entropy change Of the surroundings at 2048K. Include a sign and units in your answer. 40 - (iii) Calculate the total entropy change of the reaction at 2048 K. Include a sign and units in your answer. -8200b s
  5. Two flasks, P and Q, are connected by a tube fitted with a tap. Flask P contains argon gas and flask Q is in vacuum. Assume argon behaves as an ideal gas and therefore has no intermolecular forces between its atoms. How do the entropy and energy of the System change when the tap is opened and the argon fills both flasks? Entropy of the system increases decreases increases decreases Energy of the system decreases decreases unchanged unchanged (Total for Question 5 = 1 mark) When hydrogen and oxygen are mixed in a flask, there is no reaction. When a platinum gauze is added to the flask, the mixture explodes. It can be deduced that, in the absence of a platinum gauze, the mixture of hydrogen and oxygen is C] A kinetically stabl nd thermodynamically stabl B kinetically stable and thermodynamically unstable C kinetically unstable and thermodynamically stable D kinetically unstable and thermodynamically unstable Pt gauze make it is spontaeous, so thermodynamically unstable (Total for Question 6 = 1 mark)
  6. (c) Theoretical lattice energies are calculated assuming only ionic bonding is present. Which of these is most likely to be the theoretical lattice energy of strontium iodide? o A B c D -561 kJmor' -1937kJmol-1 -1963 k] mop -1989k] mop (Total for Question 3 = 3 marks) Which of these statements is true? A B C D the enthalpy change of hydration of an ion is always negative the enthalpy change of solution of an ionic compound is always negative an endothermic enthalpy change of solution indicates that an ionic compound will be insoluble the more exothermic the lattice energy of an ionic compound, the more soluble it is likely to be (Total for Question 4 = 1 mark) Which sequence shows the elements in order of increasing standard entropy? o A B c D He(g) 02(g) os(S) os(s) < 02(g) He(g) < Hg(l) Hg(l) < Hg(l) Hg(l) He(g) < 02(g) Os(s) < os(s) < Ol(g) He(g) (Total for Question 5 = 1 mark) 14 In which series does the standard molar entropy of the compounds increase? A CaO(s) < H20(l) < coz(g) < S02(g) O B GO(s) < H20(1) < S02(g) < C02(g) C so.(g) < coa(g) < H.O(I) < GO(s) O D C02(g) < S02(g) < H20(1) < CaO(s) degree of freedom is linear in shape. s (Total for Question 14 = 1 mark) The degree of ofreedom is higher to S02, bceuse of its strucutre compare t o C02, which
  7. Answer ALL the questions. Write your answers in the spaces provided. 1 This question is about oxides of iron. (a) The equation for the reduction Of iron(lll) oxide by carbon is shown. Fez03(s) + 3C(s) 2Fe(s) + 3CO(g) Some data relating to this reaction are shown. Substance AHO / kJ mol-' SO,'JK-' mol-' -824.2 87.4 5.7 27.3 -1 10.5 197.6 (i) Calculate the standard enthalpy change, A", for the reduction of iron(lll) oxide by carbon. (ii) Calculate the entropy change, ASsystem, for this reaction.
  8. (iii) Calculate the temperature at which this reaction becomes feasible, using your answers from (a)(i) and 00 D (b) The equation for the reduction Of iron(lll) oxide by carbon monoxide is shown. + 3CO(g) -i 2Fe(s) + = -24.8 The entropy change, for this reaction is +15.2 J mol-I (i) Explain why the reaction should be feasible at any temperature. (ii) Explain how an increase in temperature would affect ofthis reaction. No calculation is required. As the denominator increases, the entropy of the surrounding dec reases,
  9. Enthalpy change associated with the formation of I mol of an ionic compound from I their ions in gaseous state. N act Enthalpy change of atomization Enthalpy change with the formation of 1 mol of a gaseous atom from from an element in its standard state.
  10. Enthalpy change of ionisation / ionisation enthalpy Enthalpy change associated with the formation of+ve ion by loosing an electron from 1 mol of a gaseous atom. Enthalpy change of electron affinity. enthalpy change when an electron is added to 1 mole of a gaseosu atom 7 The diagram shows the Born—Haber cycle for sodium oxide. 2Nättg) + 2e- + O. 2Na(g) + •g) 2Na(S) + NazO(s) (a) Which energy change in the cycle does y represent? A the first electron affinity Of oxygen the second electron affinity of oxygen C the Sum Of the first and second electron affinities Of oxygen C] D the sum of the enthalpy change of atomisation of oxygen and the first and second electron affinities of oxygen (b) Which expression gives the enthalpy change Of formation Of sodium oxide, AH? D