Recently, a student of mine showed me a way of visualizing and planning out unit conversion-type chemistry problems that I had never seen before, so I made my own version of this visual aid. It is essentially a flow chart illustrating how many stoichiometry and dimensional analysis problems can be mapped out visually as a series of unit conversions.
You can also download a pdf version here.
This tool can be used to visualize a sequence of unit conversions to solve a variety of chemistry problems. Each box represents a quantity, and each arrow shows the conversion factor needed to move from one quantity to the next. Just be sure to use dimensional analysis to make sure the units work out!
Now students can’ t always have this chart on hand, and they will eventually want to move on from this learning aid. So there is an axiom that I think distills the essence of the chart into a single sentence.
When in doubt, convert to moles.
The concept of the mole is central to this entire unit conversion process, so if a student remembers that they can convert to and from moles from mass, volume, and/or the number of particles, then they should be able to solve most problems.
Here are some example stoichiometry problems. Go see if the unit conversion map helps you plan your dimensional analysis-based solution!
There is no comparison between that which is lost by not succeeding and that which is lost by not trying.
Francis Bacon
