# If you take 25 mL of a 500 ppb solution and add sufficient water until the volume is 100 mL, and...

## Question:

If you take 25 mL of a 500 ppb solution and add sufficient water until the volume is 100 mL, and mix thoroughly what is the concentration of the final solution? You dilute 10.0 mL of a 2.50 M solution to 500 mL, what is the final concentration?

## Dilution of Solutions:

The concentration of a solute in a solution can be decreased to a certain level by adding a known amount of solute-free solvent to the solution. This is called dilution. As most stock solutions are purchased at high concentrations, diluting solutions for experiments/analysis is common in chemical laboratories.

125 ppb, and 0.050 M

The concentration of a solute after dilution is calculated using the following formula;

{eq}\rm C_1.V_1=C_2.V_2 {/eq}

where C and V are concentration and volume of the solution and 1 and 2 denote before and after dilution, respectively.

- Diluting 25 mL of a 500 ppb solution to 100 mL would make the concentration of the final solution to be 125 ppb:

{eq}\rm C_2=\frac{C_1.V_1}{V_2}=\frac{500\;ppb\times25\;mL}{100\;mL}=125\;ppb {/eq}

- Diluting 10.0 mL of a 2.50 M solution to 500 mL would make the concentration of the final solution to be 125 ppb:

{eq}\rm C_2=\frac{C_1.V_1}{V_2}=\frac{2.50\;M\times10.0\;mL}{500\;mL}=0.050\;M {/eq}