(3 pts) The stockroom prepared a solution by dissolving 0.2300 g of Erythrosin B (MW = 879.87 g/mol) in DI water in a 250.00 mL volumetric flask. A student pipetted 5 mL of the stockroom solution into a 100.00 mL volumetric flask and diluted it to the mark with DI water. The molar concentration of the stockroom's solution in the 250.00 mL flask is
.00105M.
The molar concentration of the student's diluted solution in the 100.00 mL flask is ____M
If the student wishes to prepare 100.00 mL of a 4.50x10^-4M solution, she will need ____mL of the stockroom solution.
Hmmm.
You are given the Molarity of the stockroom solution. It is diluted by a factor of 20.
Molarity=Mstockroom/20
Now, for the second part
4.6E-4=Mstockroom/dilution factor
solve for dilution factor. Then, amount is equal to 100ml/dilution factor.
There are other ways of doing this. I will be happy to critique your work on the method you were taught.
To find the molar concentration of the student's diluted solution, we need to consider the dilution factor.
The dilution factor is the ratio of the final volume to the initial volume. In this case, the final volume is 100.00 mL and the initial volume is 5 mL. Therefore, the dilution factor is 100.00 mL / 5 mL = 20.
Since the molar concentration of the stockroom's solution in the 250.00 mL flask is 0.00105 M, we can calculate the molar concentration of the student's diluted solution by dividing the molar concentration of the stockroom's solution by the dilution factor.
Molar concentration of student's diluted solution = 0.00105 M / 20 = 5.25 x 10^-5 M
Therefore, the molar concentration of the student's diluted solution in the 100.00 mL flask is 5.25 x 10^-5 M.
Now, let's calculate the volume of the stockroom solution needed to prepare a 4.50 x 10^-4 M solution in 100.00 mL:
Using the formula:
M1V1 = M2V2
Where:
M1 = molar concentration of the stockroom solution
V1 = volume of the stockroom solution
M2 = desired molar concentration of the final solution
V2 = final volume of the solution
We can rearrange the formula to solve for V1:
V1 = (M2 * V2) / M1
Plugging in the values:
M1 = 0.00105 M
V1 = ?
M2 = 4.50 x 10^-4 M
V2 = 100.00 mL
V1 = (4.50 x 10^-4 M * 100.00 mL) / (0.00105 M)
V1 = 428.57 mL
Therefore, the student will need approximately 428.57 mL of the stockroom solution to prepare the desired 4.50 x 10^-4 M solution in 100.00 mL.