G, G°, [delta][subscript r]G, [delta][subscript r]G°, [delta]G, and [delta]G° are essential quantities to master the chemical equilibrium. Although the number of publications devoted to explaining these items is extremely high, it seems that they do not produce the desired effect because some articles and textbooks are still being written with some of these quantities that appear to be identical to others. This work attempts to clarify the differences between the six quantities using a guided-problem-solving approach instead of a more conventional expository style. A very simple chemical equilibrium, N[subscript 2]O[subscript 4](g) [equilibrium] 2NO[subscript 2](g), has been chosen as an example. Furthermore, it has been treated in the simplest possible way (as an ideal gas mixture, to thereby avoid fugacities), because the important issue is to sort out concepts and not get entangled in laborious calculations that many times obscure the didactic objective pursued. It is complemented with a small computational tool (a MATLAB script) to quickly perform calculations and graphs. In addition, the script allows one to analyze interactively (through a user-friendly interface) the disturbances that occur in chemical equilibrium owing to changes in temperature and pressure. An exhaustive review of the literature has also been made to select the most useful sources to study this problem.