From purely an intuitive approach, it is easy to understand how a density meter can determine concentrations. If you were to measure the density of a pure water sample, you would find its density to be 0.9982 g/cm³ at 20ºC.
Now if you were to take 1g of NaCl (salt) and add this to the same pure water to make a 100 g solution, the resulting 1% solution of NaCl would now have a density of 1.0053 g/cm³ at 20ºC. Add yet another gram of NaCl and the 2% solution now will have a density of 1.0125 g/cm³ at 20ºC. If you were to continue this process, you would soon have a complete table of % NaCl vs. density at 20ºC. Subsequently, you are now able to find the concentration of an unknown NaCl solution.
The example above only discusses the concentration determination of NaCl. However, this same type of relationship is true for many commonly used solutions and many such tables already exist in the literature. But it is not too difficult to make new tables as required. This type of application is called a “two component” or binary solution; whereas chemical “A” is dissolved into chemical “B”. These chemicals “A” and “B” can be a solid dissolved in a liquid or a liquid dissolved into a second liquid. An example of the latter is the %Toluene in nHeptane. Using the DDM 2911, this analysis becomes extremely user friendly.
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