July 1st, 2012 
admin 
When two or more solutions of different concentration or strengths are mixed together then this mixing will yield another solution having a totally different strength as compare to the reacting solutions. Molarity is one of the most commonly employed units of concentration and it can be defined as the number of moles of solute that are contained in a liter of solution. In case of mixing of two solutions of different molarities that are in diverse amounts as well; their molarity is find out by a different way.
So in order to find out the fresh concentration of the solute, amount of the solute which is stated in term of moles which is simultaneously situated in the solution possesses the volume which is equal to the summation of two solutions that are mixed together. In lab practices, it rarely occurs that a homogenous solution is present. Most of the times, chemists have to deal with the mixture of solution. If their concentration is not accurately determined, then it will definitely yield to the wrong outcomes and all the research or other concerned workings will go in vain. Therefore, it is very essential to find out the correct concentration of a mixing in terms of molarity in order to make the results authentic.
Steps for calculating the molarity of mix:
1. Find out the volume as well as concentration of the two reacting solutions. The amount of solute that was present initially prior to mix should be known. For e.g. suppose that chemical reaction does not occur after mixing and both solutions do possess these listed parameters given below:
10 milli-liters of 0.1 M HCl are present in Solution-A and 12 milli-liters of 0.5 M HCl. are present in Solution-B.
2. Find out the total volume in liter that is present in both the Solution-A and Solution-B. Now make conversions of unit of volume i.e. convert volume from milli-liters into liters. If we see the e.g. given in step# 1, 10 milli-liters of Solution-A are present that are divided by 1000 and the result will be 0.01 liter and the same procedure will be used for Solution-B that will give 0.012 liter.
3. Now the number of moles that are present in both the Solution-A and Solution-B are calculated. Formula for finding out moles can be represented as:
Moles = Molarity * Volume
By using this formula, total number of moles calculated for the Solution-A and Solution-B are 0.001 moles and 0.006 moles respectively.
4. Find out the sum of both values of total number of moles present in Solution-A and Solution-B.
0.01 moles + 0.006 moles = 0.007 moles of HCl.
5. Total volume is determined by summing up the individual volume present in Solution-A and Solution-B. i.e.
0.01 liter of Solution-A + 0.012 liter of Solution-B = 0.022 liter of final solution.
6. Molarity of the resultant solution is determined by using the formula of molarity i.e.
Molarity = number of moles of solute/ liters of solution
Molarity = 0.007 moles of HCL / 0.022 liters of final solution
Molarity of mixing = 0.029 M
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