g NH 3 titrated by a strong acid eg HNO 3 Confirmation of this is the

G nh 3 titrated by a strong acid eg hno 3

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e.g., NH3titrated by a strong acid, e.g., HNO3. Confirmation of this is the equivalence point, approximately 5. The equivalence point of NH3and HNO3is approximately 5.
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Chem 162-2012 final exam + solutions 37 36 Chem 162-2012 Final Exam + Answers Chapter 18 - Thermodynamics Free energy calculations Use the given data at 298 K to calculate G° for the reaction 2Cl 2 (g) + SO 2 (g) SOCl 2 (g) + Cl 2 O(g) Substance: Cl 2 ( g ) SO 2 ( g ) SOCl 2 ( g ) Cl 2 O( g ) Δ H ° f (kJ/mol): 0 –296.8 –212.5 80.3 S °(J/K • mol): 223.0 248.1 309.77 266.1 A) 129.3 kJ B) 133.6 kJ C) 196.0 kJ D ) 199.8 kJ E) 229.6 kJ Δ H o = (-212500 + 80300) – ((2x0) -296800) = 1.646 x 105 J Δ S o = (309.77 + 266.1) – ((2x223.0) + 248.1) = -118.23/K Δ G o = Δ H o - T Δ S o Δ G o = (1.646 x 105) – (298 x -118.23) = 1.9983 x 105J = 199.83 kJ
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Chem 162-2012 final exam + solutions 38 SECTION 4 Covers material not covered on the other exams 37 Chem 162-2012 Final Exam + Answers Chapter 20 – Nuclear Chemistry Radioactive decay kinetics 92 238 U undergoes alpha decay with a half-life of 4.5 x 10 9 years. What is the instantaneous rate of decay for a 1.0 g sample of 92 238 U? 3.156 x 10 7 sec = 1 year. A . 1.2 x 10 4 nuclei sec B. 520 nuclei sec C. 4.32 x 10 6 nuclei sec D. 8.2 x 10 3 nuclei sec E. 2.4 x 10 9 nuclei sec Begin by finding λ t 1/2 = 0.693/ λ (4.5x109y x (3.156x107s/y)) = 0.693/ λ λ = 4.88 x 10 -18 The answer options are in nuclei per second. Therefore, convert 1.0g into atoms (i.e., convert grams into nuclei). 1.0g x (1mol/238g) x (6.022x10 23 atom/mol) = 2.53 x 10 21 atoms 238 92 U Instantaneous rate = λ [N] Instantaneous rate = 4.88 x 10 -18 x (2.53x10 21 ) = 1.23 x 10 4 atom/s
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Chem 162-2012 final exam + solutions 39 38 Chem 162-2012 Final Exam + Answers Chapter 20 – Nuclear Chemistry Miscellaneous The purpose of control rods in nuclear reactors is
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Chem 162-2012 final exam + solutions 40 39 Chem 162-2012 Final Exam + Answers Chapter 19 – Electrochemistry Free energy, equilibria and cell potential calculations/Nernst equation A concentration cell consists of two Al/Al3+electrodes. The electrolyte in compartment A is 0.050 M Al(NO3)3and in compartment B is 1.25 M Al(NO3)3. What is the voltage of the cell at 25°C? -
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Chem 162-2012 final exam + solutions 41 40 Chem 162-2012 Final Exam + Answers Chapter 20 – Nuclear Chemistry
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