Question

QUESTION 1 For a reaction, a plot of In K versus inverse temperature is found to be linear and fits the following equation: y = -1,714x + 5.64. What is the value of AH? Give your answer with units of kJ/molk; however, you should not type in the units QUESTION 2 If you find that the standard Gibbs free energy change for a reaction is 1.98 kJ/molk, what is the equilibrium constant for the reaction at 25.0°C? Be careful with your units in the calculation.

1a) For a reaction, a plot of ln K versus inverse temperature is found to be linear and fits the following equation: y = -1,714x + 5.64. What is the value of ΔH? Give your answer with units of kJ/molK; however, you should not type in the units

b) If you find that the standard Gibbs free energy change for a reaction is 1.98 kJ/molK, what is the equilibrium constant for the reaction at 25.0 ^oC? Be careful with your units in the calculation.

Answer 1

1)

The relation between K and T is:

K = A*e^(-Ho/RT)

taking ln on both sides, above expression becomes,

ln K = ln A - Ho/RT

So, slope between ln K and 1/T will have a value of -Ho/R and y intercept is ln A

So, Ho can be calculated from slope

slope = -Ho/R

-1714 = -Ho/8.314

Ho = 1.43*10^4 J/mol

Ho = 14.3 KJ/mol

Answer: 14.3

2)

T= 25.0 oC

= (25.0+273) K

= 298 K

ΔGo = 1.98 KJ/mol

ΔGo = 1980 J/mol

use:

ΔGo = -R*T*ln Kc

1980 = - 8.314*298.0* ln(Kc)

ln Kc = -0.7992

Kc = 0.4497

Answer: 0.450