Greetings,
This post covers a topic most chemistry students find quite challenging; unit conversions for compound solutions. These calculations involve the molar concentration concept and so we find that the mole unit is central regarding workup of these problem types. Conversions involving the density unit will also be discussed.
The "problem" students tend to have with solution problems is: 1) Where to begin?, 2) What intermediary units are involved?, and 3) What is the final unit conversion? These solution problems become much easier if we understand at the outset that the same general unit conversions occur over and over again: Only the numbers and compound formulas change! As mentioned above, solving solution problems revolves around the mole unit; specifically the total number of solute compound molecules/ formula units present, in terms of number of moles. The following graphic illustrates the point.
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To use the map you simply recognize the given information and problem goal, then identify the corresponding parts on the map and label them start and finish, respectively. Follow the path through to the goal to get the actual unit conversions, indicated by the clouds. Note also the distinction between "solution" and "solute". "Solution" involves bulk properties of the entire mixture, which are mass and volume. The conversions between mass and volume use the solution density as a conversion factor. Also, there is only one conversion between a property of the solution (volume )and a property of the solute (moles): The solution molarity is used here.
That's all for this post. My next post will feature actual examples of the concepts laid out here.
Have a good one!
A Publication of http://www.ExcellenceInLearning.biz
This post covers a topic most chemistry students find quite challenging; unit conversions for compound solutions. These calculations involve the molar concentration concept and so we find that the mole unit is central regarding workup of these problem types. Conversions involving the density unit will also be discussed.
The "problem" students tend to have with solution problems is: 1) Where to begin?, 2) What intermediary units are involved?, and 3) What is the final unit conversion? These solution problems become much easier if we understand at the outset that the same general unit conversions occur over and over again: Only the numbers and compound formulas change! As mentioned above, solving solution problems revolves around the mole unit; specifically the total number of solute compound molecules/ formula units present, in terms of number of moles. The following graphic illustrates the point.
.png)
To use the map you simply recognize the given information and problem goal, then identify the corresponding parts on the map and label them start and finish, respectively. Follow the path through to the goal to get the actual unit conversions, indicated by the clouds. Note also the distinction between "solution" and "solute". "Solution" involves bulk properties of the entire mixture, which are mass and volume. The conversions between mass and volume use the solution density as a conversion factor. Also, there is only one conversion between a property of the solution (volume )and a property of the solute (moles): The solution molarity is used here.
That's all for this post. My next post will feature actual examples of the concepts laid out here.
Have a good one!
A Publication of http://www.ExcellenceInLearning.biz
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