How many mL of SCN^-1 and water to put in a 10 mL solution with 5 mL of Fe^3+ already in it?...
We're finding those values to make standard solutions of
0.00 mM FeSCN^2+
0.020 "
0.040 "
0.060 "
0.080 "
0.100 "
I know that you have to use M1*V1=M2*V2,but I'm not sure where to put what, or how to deal with mM in this equation.
We are also given the molarity of Fe3+ as 0.200 M, and SCN- as 2.00E-4
If someone could just show me the process of how to do one or two of them, I can do the rest.
Thanks!
To determine the amount of SCN^-1 and water needed to make the standard solutions, you can use the dilution equation:
M1V1 = M2V2
Where:
- M1 is the initial molarity of the solution
- V1 is the initial volume of the solution
- M2 is the final molarity of the solution
- V2 is the final volume of the solution
In this case, you want to determine the volumes of SCN^-1 and water needed to make standard solutions with different molarities.
Let's start with the first case where you need to make a 0.00 mM FeSCN^2+ solution in a 10 mL total volume. Since SCN^-1 and Fe^3+ react in a 1:1 molar ratio to form FeSCN^2+, the concentration of SCN^-1 should be exactly the same as the desired concentration of FeSCN^2+.
1. Calculate the moles of Fe^3+ in the 5 mL solution using its molarity (0.200 M) and volume:
Moles of Fe^3+ = (0.200 M) * (0.005 L) = 0.001 mol
2. Since the reaction is 1:1, the moles of SCN^-1 needed to react completely with the Fe^3+ are also 0.001 mol.
3. Now, using the molarity of SCN^-1 (2.00E-4 M), you can calculate the volume of SCN^-1 needed to provide 0.001 mol of SCN^-1:
Volume of SCN^-1 = Moles of SCN^-1 / Molarity of SCN^-1
Volume of SCN^-1 = 0.001 mol / (2.00E-4 mol/L) = 5 mL
So, to make a 0.00 mM FeSCN^2+ solution, you'll need to add 5 mL of SCN^-1 to the 5 mL of Fe^3+ solution.
For the other standard solutions, you can follow the same process. Remember that the volume of Fe^3+ remains constant at 5 mL, and you'll need to adjust the volume of SCN^-1 and water accordingly to achieve the desired final volume (10 mL).
For example, for the 0.020 mM FeSCN^2+ solution, you can follow these steps:
1. Calculate the moles of Fe^3+: Moles of Fe^3+ = (0.200 M) * (0.005 L) = 0.001 mol
2. Calculate the moles of SCN^-1 needed: Moles of SCN^-1 = 0.020 mM * (10 mL / 1000) L = 0.0002 mol
3. Calculate the volume of SCN^-1 needed: Volume of SCN^-1 = Moles of SCN^-1 / Molarity of SCN^-1 = 0.0002 mol / (2.00E-4 mol/L) = 1 mL
4. Calculate the volume of water needed: Volume of water = Total volume - Volume of SCN^-1 - Volume of Fe^3+ = 10 mL - 1 mL - 5 mL = 4 mL
Therefore, to make a 0.020 mM FeSCN^2+ solution, you'll need to add 1 mL of SCN^-1 and 4 mL of water to the 5 mL of Fe^3+ solution.
You can apply the same process to calculate the volumes of SCN^-1 and water for the other standard solutions.