This program is designed to help students in introductory chemistry classes understand the concept of extent of reaction.
The program starts with a simple reaction where it takes 2 molecules of A and 1 molecule of B to produce 2 molecules of C. The reaction starts with 1 mole of A and 1 mole of B. As you move the reaction progress slider to the right, the extent of reaction increases, the amount of reactants A and B decrease, and the amount of C increases. If you move the slider to the end, all the moles of A will be used up and the reaction cannot progress any further. The slope of the lines on the graph is equivalent to their coefficient in the reaction, while their endpoints correspond to their amounts at minimum and maximum extent.
You can change the coefficients on the products and reactants to simulate various reactions. You can also change the initial amounts of the products and reactants to simulate various conditions. To simulate the reaction of N2 + 3H2 ⇔ 2NH3, set the coefficient on A to 1, the coefficient on B to 3, the coffieicent on C to 2, and the coefficient on D to 0. Then set the initial amounts to the desired values.