If you were going to graphically determine the enthalpy The equilibrium constant
ID: 103603 • Letter: I
Question
If you were going to graphically determine the enthalpy The equilibrium constant, K, of a certain first order reaction was measured at two temperatures, T r, for this reaction, what points would you plot? The data is shown in this table Number Number T(K) K 275 3.11 875 7.55 avoid rounding errors, use three significant figures in the x values and four significant figures in point 1 Number Number e y values. 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 J/molExplanation / Answer
We need to plot lnK on y axis and 1/T on x axis
K = 3.11
ln K = ln (3.11) = 1.13462
T = 275.0
1/T = 0.00364
point 1 is:
x = 0.00364
y = 1.13462
K = 7.55
ln K = ln (7.55) = 2.02155
T = 875.0
1/T = 0.00114
point 2 is:
x = 0.00114
y = 2.02155
----------------------------------------------------------------------------
rise = (y1-y2) = 1.13462 - 2.02155 = -0.88692
rise = (X1-X2) = 0.00364 - 0.00114 = 0.00249
slope = rise/run
= -0.88692/0.00249
= -355.69381
----------------------------------------------------------------------------
use
slope = - delta H/R
= -355.69381 = -delta H/8.314
delta H = 2957 J/mol
Answer: 2957 J/mol