A chemist dissolves 0.095 g of CuSO4 · 5H2O

in water and dilutes the solution to the mark
in a 500-mL volumetric flask. A 39.7-mL
sample of this solution is then transferred to a
second 500-mL volumetric flask and diluted.
What is the molarity of CuSO4 in the second
solution?

To determine the molarity of CuSO4 in the second solution, we need to know the amount of CuSO4 in the original solution and the final volume of the second solution.

1. Calculate the amount of CuSO4 in the original solution:
The original solution was prepared by dissolving 0.095 g of CuSO4 · 5H2O in water and diluting it to a total volume of 500 mL.

Since the molar mass of CuSO4 · 5H2O is 249.68 g/mol, we can calculate the number of moles of CuSO4:
Moles of CuSO4 = mass / molar mass
= 0.095 g / 249.68 g/mol
= 0.00038 mol

2. Calculate the amount of CuSO4 in the transferred sample:
A 39.7 mL sample of the original solution is transferred to the second flask.

The moles of CuSO4 in the transferred sample will be the same as the moles in the original solution, as the amount of solute does not change during dilution.

3. Calculate the final volume of the second solution:
The second flask has a volume of 500 mL, but only a 39.7 mL sample was transferred into it.

Since the final volume is 500 mL, we can assume that the transferred sample was diluted to fill the remaining volume. Thus, the final volume is 500 mL.

4. Calculate the molarity of CuSO4 in the second solution:
Molarity (M) = moles of solute / volume of solution (L)

Moles of CuSO4 = 0.00038 mol
Volume of solution = 500 mL = 0.5 L

Molarity of CuSO4 = 0.00038 mol / 0.5 L
= 0.00076 M

Therefore, the molarity of CuSO4 in the second solution is 0.00076 M.

Find M in the first one first.

mols CuSO4.5H2O = grams/molar mass = ?
M = mols/0.500L = ?M

In the second flask, we have
?M from first x (39.7/500 = xM.