Whenever we begin to discuss a new subject we have to learn the language that accompanies it. Fortunately, for discussing solutions, a great deal of the language was already covered in CHM1045. The problems that might occur here stem from how much of this language you actually remember and whether or not you can apply what you remember to new problems.

Review of Terms:

There are Five main ways we describe the concentration of solutions: 1) Molarity; 2) Molality; 3) Weight Percent; 4) Mole Fraction; and 5) Parts Per Million or Billion. You should know the meaning of each of these terms and more importantly how to convert from one to the other. I have added a conversion calculator at the bottom of this page to help you check your homework etc. But don't become too reliant on it since it will not be available during exams.

Molarity: The molarity of a solution is calculated by taking the moles of solute and dividing by the liters of solution. Molarity is designated by a capital "M".

Molality: The molality of a solution is calculated by taking the moles of solute and dividing by the kilograms of solvent. Molality is designated by a lower case "m".

Weight Percent(or Mass Percent): The weight percent of a solution is calculated by taking the mass of a single solute and dividing it by the total mass of the solution. This can be in grams or kilograms as long as the units of both are expressed in the same manner. The ratio is then multiplied by 100%. The weight percent is designated by Wt% and sometimes w/w%.

Mole Fraction: The mole fraction of a single solute in a solution is simply the number of moles of that solute divided by the total moles of all the solutes/solvents. The mole fraction of solute i is written as X_i.

Parts Per Million(PPM) and Parts per Billion (PPB): "Parts per" is a convenient notation used for low and very low concentrations. Generally speaking it is very similar to weight percentage - 1% w/w means 1 gram of substance per every 100 g of sample and it is (although very rarely) named pph - parts per hundred. Other abbreviations stand for:

ppq is more a theoretical construct than a useful measurement, chances are you will never see it in use. Parts per million also can be expressed as milligrams per liter (mg/L).

Practice, Practice, Practice:

Need more practice? Try any of the quizzes shown here: http://lrc-srvr.mps.ohio-state.edu/under/chemed/qbank/quiz/bank9.htm

In a hurry or want to check your answers? Use this Conversion Calculator: