What is the concentration of (M) of KCl in a solution made by mixing 25.0 ml of 0.100 M KCl with 50.0 mL of 0.100 M KCl?
+561 First, we need to find the total number of moles in the combined solution.
Firstly, all values should be in the same units for volume. In your case, concentration is in M (AKA mol per dm^3), meaning we need to convert the volume's ml to dm^3 by dividing by 1000.
\(25 ml=0.025 mol dm^{-3}\)
\(50ml=0.05moldm^{-3}\)
Secondly, we multiply these volumes by the concentrations to find the number of moles in your combined solution.
\(0.025\times0.1=0.0025mol\)
\(0.05\times0.1=0.005mol\)
\(0.0025+0.005=0.0075mol\)
Thirdly, we find the combined volume by adding the two volumes together.
\(0.025+0.05=0.075dm^{3}\)
Finally, we divide the final number of moles by the final volume to give the final concentration.
\(0.0075/0.075=0.1M\)
In this case, because the concentrations of the initial solutions were identical, the final concetration is the same. However, this method can be used for solutions with different concentrations.
