Keywords: Signals Notebook, Reaction Molarity, Limiting Reagent, Solvent Ratio, Total Volume, Molarity calculation
Reaction Molarity is a single value for the whole reaction. It is calculated by the moles of the limiting reagent divided by the total reaction of volume. The total reaction volume is the sum of volumes of all the solvents plus the volumes of any liquid reagents. Therefore, calculating Reaction Molarity helps us in getting the concentration information.
Reaction Molarity = Limiting Moles / Solvent Ratio
For more details please refer the example below:
Limiting Moles = 10.0 μmol
Total Volume = 5L (2L +3L)
Reaction Molarity = Limiting Moles / Solvent Ratio = 10/5 = 2μmolar
Please refer the below use case to relate the above information:
A chemist plans an intended reaction molarity (say 2 mmol) and want to define the solvent amount relative to the limiting reagent to have that molarity. Once that molarity is reached, they subsequently add a reagent that is a liquid and will make a significant difference to the total reaction molarity. The chemist will now want to know how much solvent to use to match the intended molarity in that solvent, and then have the total reaction molarity including the extra volume from the reagents calculated as a different value.
In reference to above statement please refer the below example:
Chemist intends to have Reaction molarity = 2mmol
They subsequently add 1gm reagent and mass gets increased from 3.8 mg to 4.8 mg
Now in order to maintain the molarity he/she will have to add more solvent accordingly (i.e from 5L to 6.3L)
