Question

The equilibrium constant K for a certain reaction was measured as a function of temperature (in Kelvin). A plot of ln(K) versus 1/T for this reaction gives a straight line with a slope of 1.352 x 104 K and a y-intercept of -14.51. Determine the value of ΔH° for this reaction.

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

- 1.124 x 10⁵ J = -1.124 x 10² kJ

Step-by-step explanation:

The change in Gibbs free energy is related to the equilibrium constant K by

ΔGº = - RTlnK

But, we also know that by definition

ΔGº = ΔHº - TΔSº

thus

ΔHº - TΔSº =  - RTlnK

lnK = - ΔHº/RT + ΔSº/R

This equation has the form y = mx + b where m is the slope and b is the y intercept.

Therefore, a plot lnK versus 1/T will give us a straight line with slope ,        m= - ΔHº/R.

We know m = 1.352 x 10⁴ K

so we can solve for ΔHº

ΔHº = - mR = 1.352 x 10⁴ K  x 8.314 J / K = - 1.124 x 10⁵ J = -1.124 x 10² kJ