mathematics

A solid grasp of proportional thinking is crucial to being able to solve all sorts of problems in chemistry as well as “real life” situations. While many students seem to intuitively understand that one mole is equal to 6.022 x 10²³ particles when the analogy is drawn to a dozen eggs, for some, this sort of equality is a puzzling mystery.

Most students, and many of my (now former) colleagues, find stoichiometry to be one of the most challenging topics in a first year (and yes, even a second year) chemistry class. But my students and I have always looked forward to the challenge, and the fun. Certainly, stoichiometry means diligent work, and for some it means frustration.

This worksheet is intended to be used as a "Guided Instructional Activity" (GIA). Students read a statement that gives a either a conversion factor or a pair of related measures and then write the information as two equivalent fractions ("conversion factors") and as an equality.

The three "Guided Instructional Activities" in this activity are three cooperative learning pieces in which students are guided through the process of converting from one unit to moles (or moles to a unit) by the method of "unit analysis" (dimensional analysis). Students alternate steps in the process and evaluate the success of each step.

This worksheet asks students to do basic conversions of mass or molecules to moles and vice versa. The worksheet requires students to complete their work in a particular format and to inlcude number, unit, and chemical identity for each item in the "given," in each conversion factor, and in the answer.

This worksheet is intended to be used as a "Guided Instructional Activity" (GIA). It asks students to find the molar mass of selected elements and write the molar mass as two equivalent fractions ("conversion factors") and as an equality. In each representation, students are forced to give the numeral of the measure, unit, and identity of the chemical.