- You can either create a new excel and copy and paste enthalpy and entropy data for each molecule over, or you can save your most recent file “save as” and update it to reflect that it will now contain Gibbs Energy data modeling.
- Organize columns to display the enthalpy and entropy data for each molecule, making sure that their units agree (Gibbs Energy is usually expressed in kJ/mol rather than J/mol so you will probably want to convert your entropy data to kJ). If a molecule’s calculated entropy data has a large split in it due to the temperature range split, you can use the full temperature range trendline from the total entropy graph to calculate a continuous full temperature range entropy data set to use for the Gibbs excel this week. Email me if you aren’t sure how to do this.
- At the top of your excel page, organize in your specific balanced chemical equation.
- Create two columns; one for the change in entropy of your equation and one for the change in enthalpy of your equation.
- Fill in each column by solving for the enthalpy or entropy of reaction (recall the sum of products minus the sum of reactants [don’t forget you’ll need to use the balanced coefficients!]).

- Using the equation for Gibbs Free energy of a reaction (see lecture video), create and calculate a column for the change in Gibbs free energy at each temperature in your temperature range.
- In order to calculate a change in Gibbs energy at a given temperature you have to have entropy and enthalpy of reaction data at that temperature also. Your temperature range should start at 298K (or 300K) and increase to at least 1200 K. Most molecules have data above 1200 K (typically up to 6000 K). If your molecule’s data stops short of 1200 K, use the calculated trendline coefficients to calculate data points at temperatures up to 1200 K. You can email me (only after trying yourself first at least once) and we can Zoom!
- You will only have one single Gibbs energy column for your entire equation! A lot of work has led up to this column.

- Graph your equation’s Gibbs Free energy data vs. temperature.
- Find the best fit trendline and report using correctly formatted trendlines.
- Graph your equation’s enthalpy of reaction, entropy of reaction and Gibbs Free energy of reaction all overlayed on a single graph.

- MUST BE ON EXCEL FOR SPREADSHEET, NOT ANOTHER GRAPHING PROGRAM

Answer the following questions with respect to your completed excel data from this week. Answer to the best of your ability, sometimes you are being asked what you think. Cite any resources that you use.

1. Were you able to predict that the Gibbs Free energy of your reaction would be positive or

negative at all temperatures? Why or why not?

2. How did the Gibbs Free energy of your reaction change as temperature increased? What was the

best fit trendline that described this?

3. Using your own words, describe your dG vs T graph. Describe what the graph is showing, what

information it is giving about your reaction and how dG changes with T according to the graph.

4. Using your own words, describe your dG, dS, and dH vs T graph. Describe what the graph is

showing, what information it is giving about your reaction and how each component changing

with T (and compared to one another) according to the graph.

5. Describe how a reaction could be spontaneous while being endothermic.