The Expressing Concentrations Tutorial (HTML5) is an interactive animation that defines solutions (solute + solvent), creates a "map" of the units used to express solution concentration, and presents several types of calculations that convert one concentration unit into another concentration unit. Chem21Labs animations provide a safe environment for learning . . . . students receive "full credit" when they complete the animation correctly - it does not matter how many times they miss part of it and have to start over. This animation is typically a lecture assignment, but can be assigned as a post-lab activity for a lab dealing with solution concentrations (i.e. Oscillating Chemical Reaction lab) . . . . assigning the same interactive tutorial in lecture and lab is a great way to "connect" the learning between the two classes.
- Students learn that solutions are comprised of a solute and a solvent.
- The Law of Conservation of Matter provides the central relationship . . . .
g Solute + g Solvent = g Solution
- This equation is "expanded" into the "map" shown to the right.
- Students "re-create" this map by dragging / dropping units in the correct spot.
- At the end of the animation is a series of calculations where students use this "map" to express a solution's concentration in Molarity, molality, mass percent, ppm, mole fraction, or Normality.
- If the student miscalculates a concentration, they are shown the step-by-step solution . . . however, they must restart the animation.
- Students receive "full credit" when they complete the animation correctly - it does not matter how many times they must restart it.