Question

for the calculations performed with the experimental data obtained, which of the following best describes why it is necessary to assume that deltaH and deltaS are temperature independent values. this assumption permits use of a linear equation to fit the data, this assumption allows us to average the data, this assumption allows entropy to be ignored when enthalpy changes are large, this assumption allows entropy to be ignored when enthalpy changes are small, this assumption allows entropy to be ignored when calculating deltaG values

Answer 1

Solution :

Mathematical relation between free energy, delta H and delta S.

Delta G = Delta H – T delta S

We know the relation between delta G and equilibrium constant.

Delta G = - RTlnK

When we plug for delta G we get

-RTlnK = Delta H – T delta S

Lets divide complete equation by   (-RT ) then we get

lnK = - (Delta H / RT ) + Delta S / R

Now if we look at above equation then we we have equilibrium constant, Delta H and delta S in it.

Above equation is in the form of y = mx + c

Here x = 1 /T

And slop of this equation is      “- (delta H / R )”

To make this above equation resemble to y = mx + c and get linear plot to determine the value of delta H and delta S from k or vice versa at different T we must assume delta H and delta S to be constant.

So the linear fit is important here.

And answer for this is “This assumption permits use of a linear equation to fit the data ”