Question

It is found the equilibrium constant increases by a factor of four when the temperature is increased from 25°c to 40°c. The value of deltaH°

Answer 1

The value of ΔH° = 71.65 KJ/ mol

Given,

initial equilibrium constant of the reaction is K₁

equilibrium constant of the reaction after change in temperature K₂ = 4 K₁

initial temperature (T₁) = 25° C = 298 K

final temperature (T₂) = 40° C = 313 K

Heat of the Reaction ΔH°

universal gas constant (R) = 8.314 J/mol. K

Formula,

2.303 log $\frac{K_2}{K_1}$ = $\frac{\Delta H^0}{R} \times \frac{T_2- T_1}{T_1T_2}$

= 2.303 log $\frac{4K_1}{K_1}$ = $\frac{\Delta H^0}{8.314} \times \frac{313- 298}{(298)(313)}$

= 2.303 log(4) = $\frac{\Delta H^0}{8.314} \times \frac{15}{93274}$

= 1.386  = $\frac{\Delta H^0}{8.314} \times \frac{15}{93274}$

= 1.386 × $\frac{93274}{15}$  = $\frac{\Delta H^0}{8.314}$

= 1.386 × 6218.26 =  $\frac{\Delta H^0}{8.314}$

= 8618.5 × 8.314 = ΔH°

ΔH° = 71654.2 J/mol = 71.65 KJ/ mol

Heat of the reaction ΔH° = 71.65 KJ/ mol