The equilibrium constant, K, of a certain first order reaction was measured at t

Question

The equilibrium constant, K, of a certain first order reaction was measured at two temperatures, T. The data is shown in this table.

The equilibrium constant, K, of a certain first order reaction was measured at two temperatures, T. If you were going to graphically determine the enthalpy, AH°, for this reaction, what points would you plot? The data is shown in this table Number Number T(K) K 225 3.22 7256.75 To avoid rounding errors, use three significant figures in the x values and four significant figures in the y values point 1 Number Number point 2 Determine the rise, run, and slope of the line formed by these points rise run slope Number Number Number What is the standard enthalpy of this reaction? Number click to edit J/ mol

Explanation / Answer

We need to plot lnK on y axis and 1/T on x axis

K = 3.22

ln K = ln (3.22) = 1.16938

T = 225.0

1/T = 0.00444

point 1 is:

x = 0.00444

y = 1.16938

K = 6.75

ln K = ln (6.75) = 1.90954

T = 725.0

1/T = 0.00138

point 2 is:

x = 0.00138

y = 1.90954

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rise = (y1-y2) = 1.16938 - 1.90954 = -0.74016

rise = (X1-X2) = 0.00444 - 0.00138 = 0.00307

slope = rise/run

= -0.74016/0.00307

= -241.47757

----------------------------------------------------------------------------

use

slope = - delta H/R

= -241.47757 = -delta H/8.314

delta H = 2008 J/mol

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