Physical Constants and Units Used in Thermodynamics PDF

Physical Constants and Units Used in Thermodynamics Table 13-1 Some Physical Constants and Units Used in Thermodynamics Boltzmann constant, k = 1.381 × 10−23 J/K Avogadro’s number, N = 6.022 × 1023 mol−1 Faraday constant, F = 96,480 J/V mol...

Physical Constants and Units Used in Thermodynamics Table 13-1 Some Physical Constants and Units Used in Thermodynamics Boltzmann constant, k = 1.381 × 10−23 J/K Avogadro’s number, N = 6.022 × 1023 mol−1 Faraday constant, F = 96,480 J/V mol Gas constant, R = 8.315 J/mol K (= 1.987 cal/mol K) Units of ΔG and ΔH are J/mol (or cal/mol) Units of ΔS are J/mol K (or cal/mol K) 1 cal = 4.184 J Units of absolute temperature, T, are Kelvin, K 25 °C = 298 K At 25 °C, RT = 2.478 kJ/mol (= 0.592 kcal/mol)  Homework Question Homework 3 2-ch13 ) A reaction with ∆H < 0 and ∆S > 0 is: A. always exergonic. B. at equilibrium. C. physically impossible. D. always endothermic. Living Cells and the Second Law of Thermodynamics the order produced within cells as they grow and divide is compensated for by the disorder they create in their surroundings – living organisms take free energy from, and return heat and entropy to, their surroundings Standard Free-Energy Change Is Directly Related to the Equilibrium Constant for the general reaction aA + bB → cC + dD the equilibrium constant, Keq, is given by K>1 K< 1 K=0 Example N2 + O2 → 2NO Keq= 10 ^-30  Topic Question 2-Ch13. 1) Illustrate how ΔG0 correlates with Keq at equilibrium. Use an equation. 2) Explain how ΔG0 and Keq change in response to Spontaneous and Nonspontaneous reaction.  Standard transformed constants = standard free energy constants/changes standard transformed constants = physical constants based on the biochemical standard state ([H+] is 10−7 M, [H2O] is 55.5 M, [Mg2+] is 1 mM) – standard free-energy change, ∆G′° – standard equilibrium constant, K′eq Phosgene (COCl2) gas Keq= 4 x 10^9 Phosgene accident : https://www.youtube.com/watch?v=d5N8hxhJD7E&t=87s  Relationship Between K′eq and ∆G′° the relationship between K′eq and ∆G′° is: ∆G′° = -RT ln K′eq (13-3) the standard free-energy change of a chemical reaction is simply an alternative mathematical way of expressing its equilibrium constant  Topic Question 2-ch13. calculation of deltaG’0 Calculate the standard free-energy change of reaction catalyzed by the phosphoglucomutase  Homework Question Homework 4 2-ch13 ) How much transformed free energy would be required to provide cells with 7.8 mM ATP at 37 °C if both ADP and inorganic phosphate are at 0.3 mM? ∆G′° = -RT ln K′eq Gas constant = 8.31446261815324 J/K⋅mol A. +11.5 kJ/mol B. -10.1 kJ/mol C. -8.4 kJ/mol D. -11.5 kJ/mol Relationship between Equilibrium Constants and Standard Free-Energy Changes if Keq is > 1.0, its ∆G′° is negative K′eq ΔG′˚ ΔG′˚ (kJ/mol) (kcal/mol) if Keq is < 1.0, its ∆G′° is positive 103 −17.1 −4.1 102 −11.4 −2.7 the relationship is exponential 101 −5.7 −1.4 1 0.0 0.0 10₋1 5,7 1.4 10₋2 11.4 2.7 Table 13-2 Relationship 10₋3 17.1 4.1 between Equilibrium 10₋4 22.8 5.5 Constants and Standard Free-Energy Changes of 10₋5 28.5 6.8 Chemical Reactions 10₋6 34.2 8.2