Student Exploration: Equilibrium and Concentration
Vocabulary: chemical equilibrium, concentration, equilibrium, equilibrium constant, reaction quotient, reversible reaction, Le Châtelier’s principle
If Gary spends exactly as much as he earns, his savings will be in equilibrium. Equilibrium occurs when two opposing processes occur at the same rate, leading to no net change. In the Equilibrium and Concentration Gizmo™, you will investigate how equilibrium can occur in chemical reactions.
To begin, check that Reaction 1 is selected. Set Moles NO2 to 8 and Moles N2O4 to 0.
Click Play () and observe the colliding molecules.
In the Gizmo, a blue flash appears every time two reactants combine to form a product. A red flash appears every time a product dissociates into reactants.
Click Reset (), and set Moles NO2 to 0 and Moles N2O4 to 8. Click Play.
What do you notice now?
When a reaction can proceed in either direction, it is a reversible reaction. Based on what you have observed, is the synthesis of NO2 into N2O4 a reversible reaction? Explain.
Get the Gizmo ready:
Click Reset. Reaction 1 should be selected.
Set Moles NO2 to 8 and Moles N2O4 to 0.
Move the Sim. speed slider all the way to the right.
Question: What are the characteristics of reversible reactions?
Predict: Suppose you began with 8 moles of NO2 in the chamber. What do you think will happen if you let the reaction go for a long time?
Test: Click Play. Select the BAR CHARTtab and check that Moles is selected. Observe the bar chart for about 30 seconds. As time goes by, what do you notice about the bars representing moles NO2 and moles N2O4?