Question

The equilibrium constant for the reaction A+B AB is 1.80x103 dm'mol at 25°C and 3.45x10 don mal at 140%. Assume pH to be independent of temperature and calculate Atto and AS

Answer 1

lnK = - $\frac{\Delta H^{0}}{RT}$ + $\frac{\Delta S^{0}}{R}$

in the plot of lnK vs 1/T

slope = $\frac{\Delta H^{0}}{R}$

intercept = $\frac{\Delta S^{0}}{R}$

equilibrium constant , K ( dm3 mol-1)	lnK	temperature( T)	1/T
1.80*103	7.495	25 +273 = 298 K	0.00335
3.45*103	8.146	40+273 = 301 K	0.00319

now the plot is

1 2 3K 1800 3450 298 313 0.00335 0.00319 7.495 8.146 1/T Ink y=-4068.x + 21.12 R2=1 Ink 7.8 7.5 7.4 + 0.00315 0.0032 0.00325 0.0033 0.00335 0.0034 1/T

trendline equation is

y = - 4068 x + 21.12

or,  $\frac{\Delta H^{0}}{R}$ = 4068

or, $\Delta H^{0}$ = 4068 *R = 4068 *8.314 = 33821 J / mol = 33.821 KJ/mol

and $\frac{\Delta S^{0}}{R}$ = 21.12

or, $\Delta S^{0}$ = 21.12 *R =21.12*8.314 = 175.59 J/mol.K