Page 29 - A Working Method Approach For Introductory Physical Chemistry Calculations

Introduction to Physical Chemistry 13
3. Convert all units to the SI system, i.e. T should be expressed in
K etc.
4. Having identified the data, try to establish a linear correlation
between the two sets of data-remember it is not simply a case
of plotting one set of data points on the x-axis and the other set
of data points on the y-axis. Identify the linear equation in
question: y = mx + c, where m is the gradient of the graph and
c is the intercept, the point where the graph cuts the y-axis when
x = 0.
5. Create a table of the appropriate data, taking special care of:
(a) logs: did you use natural logs to the base e, for example, or
loglo?
(b) did you convert direct values (x) to their reciprocal values
(llx)?
(c) units (e.g. logs: dimensionless; l/T: K- ’, etc.).
Add as many extra columns as required. Keep the tabulated
data vertical (i.e. go down the page); this will ensure you do not
run out of space!

x-axidunit y-axidunit

6. Examine the table from step 5. From this, write down the
maximum and minimum values of x, and also the maximum
and minimum values of y:
Maximum value of x = 0; Minimum value of x = n;
Maximum value of y = 0; Minimum value of y = 0.

This determines an appropriate scale for the graph. At this
point, you might want to return to step 5, and ‘round off’ any