A chemist makes 460 mL of magnesium fluoride (MgF2) working solution by adding distilled water to 20.0 mL of a 18.8 umol/L stock solution of magnesium fluoride in water. Calculate the concentration of the chemist’s working solution in umol/L. Round your answer to the 3 significant digits
To calculate the concentration of the working solution in umol/L, we need to determine the number of moles of MgF2 in the stock solution and then divide it by the total volume of the working solution.
To calculate the number of moles of MgF2 in the stock solution:
Number of moles = concentration (mol/L) * volume (L)
Given that the concentration of the stock solution is 18.8 umol/L and the volume is 20.0 mL, we can convert the volume to liters:
Volume (L) = 20.0 mL * 1 L/1000 mL = 0.020 L
Now we can calculate the number of moles:
Number of moles = 18.8 umol/L * 0.020 L = 0.376 umol
To calculate the concentration of the working solution:
Concentration (umol/L) = number of moles / total volume (L)
Given that the total volume of the working solution is 460 mL, we can convert it to liters:
Total volume (L) = 460 mL * 1 L/1000 mL = 0.460 L
Now we can calculate the concentration of the working solution:
Concentration (umol/L) = 0.376 umol / 0.460 L ≈ 0.817 umol/L
Therefore, the concentration of the chemist's working solution is approximately 0.817 umol/L.