Question

What would be the concentration of a solution made by diluting \[45.0mL\] of \[4.2M\]\[KOH\] to \[250mL\]?

Answer 1

Hint: Adding a solvent to a solution to reduce the strength of the solute is called dilution and the process of removing solvent from a solution in order to raise the concentration of the solute in the solution is called the concentration of solution.

Complete answer:
We use the following formula for calculating the dilution,
\[{c_1}{V_1} = {c_2}{V_2}\]
Where,
\[{c_1}\] is the concentration of the starting solution
\[{c_2}\] is the concentration of the final solution
\[{V_1}\] is the volume of the starting solution
\[{V_2}\] is the volume of the final solution
It is given that,
\[{c_1} = 4.2mol{L^{ - 1}}\]; \[{V_1} = 45.0mL\] and \[{V_2} = 250mL\]
That is, we need to find the value of \[{c_2}\].
By substituting the values to the equation, we get
\[{c_2} = {c_1} \times \dfrac{{{V_1}}}{{{V_2}}}\]
\[ = 4.2mol{L^{ - 1}} \times \dfrac{{45.0mL}}{{250mL}}\]
\[ = 0.76mol{L^{ - 1}}\]
So the value of \[{c_2} = 0.76mol{L^{ - 1}}\]
It shows that the concentration should be about \[\dfrac{1}{6}\] of the original \[(\dfrac{1}{6} \times 4.2 = 0.7)\] after growing the volume by a factor of about 6.

Additional information:
Dilution is the method of weakening or deconcentrating a solution. Serial dilutions are used in microbiology to reduce bacterial concentrations to a required concentration for a particular test method or to a concentration that is easier to count when plated to an agar plate.

Note:
Remember the formula \[{c_1}{V_1} = {c_2}{V_2}\] for calculation. The dilution method maintains the volume of solute while increasing the total amount of solution, lowering the final concentration. A solution's concentration is a measurement of how much solute has dissolved in a given volume of solvent or solution. A concentrated solution is one in which the volume of dissolved solute is relatively high. A dilute solution is one in which the volume of dissolved solute is comparatively minimal.