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In this activity we will further investigate Le Chatelier's Principle in terms of temperature and pressure effects.

Up to this point we have investigated how a chemical reaction at equilibrium shifts when the amount of reactants or products is changed. We discovered that whenever a stress occurs on a reaction that is in equilibrium, the reaction shifts, to mimize the stress and, to re-establish equilibrium.

Two other possible stresses on chemical reactions at equilibrium are temperature changes and pressure changes. Let's investigate each of these possible stresses to investigate the stresses.

First you will investigate how temperature effects a reaction at equilibrium.

Open the simulation for the reaction R + G --> RG.

1a. In the reaction window look at the reaction profile in the lower right corner of the page. Is this reaction endothermic or exothermic? (NOTE: The y-axis in the reaction profile is not labeled in the window, the correct label is energy increasing from the bottom towards the top. No x-axis is provided either, so assume the reactants are on the left side of the image and products are on the right side.)

b) Design an experiment to investigate how temperature changes shift this chemical reaction at equilibrium.

Describe the experiment you performed;

Based on your investigation summarize your observations on how temperature changes effect the position of equilibrium for this reaction.

Open the simulation for the reaction R + GB --> RG + B.

2a. In the reaction window look at the reaction profile in the lower right corner of the page. Is this reaction endothermic or exothermic? (NOTE: The y-axis in the reaction profile is not labeled in the window, the correct label is energy increasing from the bottom towards the top. No x-axis is provided either, so assume the reactants are on the left side of the image and products are on the right side.)

b) Design an experiment to investigate how temperature changes shift this chemical reaction at equilibrium.

Describe the experiment you performed;

Based on your investigation summarize your observations on how temperature changes effect the position of equilibrium for this reaction.

3a. Identify any differences in how the reactions (at equilibrium) in Question 1 and Question 2 shift with a change in temperature.

b) How can you account for these differences?

c) How does temperature (heat) act as a stress on a reaction at equilibrium?

Open the simulation for the reaction R + G --> RG.

4a. Design an experiment to investigate how pressure changes (by changing the volume of the reaction container) shift this chemical reaction at equilibrium.

Describe the experiment you performed;

Based on your investigation summarize your observations on how pressure changes effect the position of equilibrium for this reaction.

5. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

6. If there is one question you would like to have answered in lecture, what would that question be?