Standard 6d Preknowledge
6d) Students know how to calculate the concentration of a solute in terms of grams per liter, molarity, parts per million, and percent composition.
CALIFORNIA FRAMEWORKS SUMMARY: All concentration units listed previously are a measure of the amount of solute compared with the amount of solution. Grams per liter represent the mass of solute divided by the volume of solution. Molarity describes moles of solute divided by liters of solution. Students can calculate the number of moles of dissolved solute and divide by the volume in liters of the total solution, yielding units of moles per liter. Parts per million, which is a ratio of one part of solute to one million parts of solvent, is usually applied to very dilute solutions. Percent composition is the ratio of one part of solvent to one hundred parts of solvent and is expressed as a percent. To calculate parts per million and percent composition, students determine the mass of solvent and solute and then divide the mass of the solute by the total mass of the solution. This number is then multiplied by 106 and expressed as parts per million (ppm) or by 100 and expressed as a percent.