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.
