5. What drives chemical change?

“What drives chemical change?” is a question of why chemical processes happen. Chemical reactions occur to different extents and at different rates. To what extent reactants will be converted into products depends on the relative potential energy of their submicroscopic components as well as on the relative  configurations these components can adopt. The speed of a process depends on the mechanism of the reaction and on the concentration of those species that limit the reaction rate. Both reaction extent and rate are affected by the temperature of the system. Understanding the drivers of chemical change is critical for predicting, explaining, and controlling processes of interest, from making soap to reducing pollution.


The Gas Exchange formative assessment was developed by a past ACCT cohort member.


The gas exchange formative assessment task asks students to interpret a representation to figure out the movement of atoms due to differences in concentration gradient. This formative assessment targets chemical causality and chemical mechanism within the topic of diffusion of gases in respiration. It is ideally used at the beginning of a cardiopulmonary, cellular respiration, or related unit in an upper level high school biology or biochemistry course.