A chemist dissolves 0.091 g of CuSO4 · 5 H2O
in water and dilutes the solution to the mark
in a 500-mL volumetric flask. A 31.8-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?
0.091g of CuSO4 *(mole/159.609 g)=moles
Moles/0.5L=M1
M1*(31.8ml)=M2*(500mL)
Some for M2:
M2=M1*[(31.8ml)/(500mL)]
To determine the molarity of CuSO4 in the second solution, we need to first calculate the number of moles of CuSO4 in the initial solution and then use that value to calculate the final molarity of the second solution.
Let's start by calculating the number of moles of CuSO4 in the initial solution.
1. Calculate the molar mass of CuSO4 · 5 H2O:
- Cu: 63.55 g/mol
- S: 32.07 g/mol
- O: 16.00 g/mol (x4 for four oxygen atoms)
- H: 1.01 g/mol (x10 for ten hydrogen atoms)
Molar mass of CuSO4 · 5 H2O:
= (63.55 g/mol) + (32.07 g/mol) + (16.00 g/mol x 4) + (1.01 g/mol x 10)
= 159.61 g/mol
2. Calculate the number of moles of CuSO4 in the initial solution:
Mass of CuSO4 · 5 H2O: 0.091 g
Moles of CuSO4 · 5 H2O = (Mass / Molar mass)
= (0.091 g) / (159.61 g/mol)
≈ 0.000571 mol
Next, let's calculate the molarity of CuSO4 in the second solution.
3. Calculate the volume of the second solution:
Volume of the initial solution: 31.8 mL
Volume of the second solution: 500 mL
As we transfer 31.8 mL to a 500 mL flask, the volume is diluted.
Volume of the second solution = 500 mL
4. Calculate the number of moles of CuSO4 in the second solution:
The number of moles of CuSO4 will remain the same as in the initial solution since we are transferring part of the solution, not adding or removing any CuSO4.
Moles of CuSO4 in the second solution = 0.000571 mol
5. Calculate the molarity of CuSO4 in the second solution:
Molarity = Moles / Volume
= 0.000571 mol / (500 mL / 1000)
= 0.00114 M
Therefore, the molarity of CuSO4 in the second solution is approximately 0.00114 M.