I need to prepare a standard iron solution by dissolving an appropriate mass of solid Fe(NH4)2(SO4)2*6H2O in water in a 1L volumetric flask containing 1 ml of 96 wt% H2SO4. The final concentration should be ~40mg/L. How would I calculate the this?
To calculate the appropriate mass of Fe(NH4)2(SO4)2*6H2O required to prepare a standard iron solution, you will need to consider the molar mass of the compound, the desired concentration, and the volume of the solution.
1. Calculate the molar mass of Fe(NH4)2(SO4)2*6H2O:
- Fe: 1 * molar mass of iron (Fe)
- N: 2 * molar mass of nitrogen (N)
- H: 8 * molar mass of hydrogen (H)
- S: 2 * molar mass of sulfur (S)
- O: 4 * molar mass of oxygen (O)
- H2O: 6 * [2 * molar mass of hydrogen (H) + molar mass of oxygen (O)]
- Sum all the masses to get the molar mass of Fe(NH4)2(SO4)2*6H2O.
2. Determine the number of moles needed to achieve the desired concentration:
- Convert the concentration from mg/L to g/L.
- Divide the concentration in g/L by the molar mass of Fe(NH4)2(SO4)2*6H2O to get the number of moles per liter.
3. Calculate the total mass needed for the desired number of moles:
- Multiply the number of moles needed by the molar mass of Fe(NH4)2(SO4)2*6H2O.
4. Determine the mass needed for a 1L volumetric flask:
- The mass calculated in step 3 represents the mass of Fe(NH4)2(SO4)2*6H2O needed for 1L of solution.
Note: The molar mass of Fe(NH4)2(SO4)2*6H2O can be found in a periodic table or calculated by adding up the molar masses of each element in the formula.
Finally, to prepare the solution, weigh out the calculated mass of Fe(NH4)2(SO4)2*6H2O and dissolve it in water in a 1L volumetric flask containing 1mL of 96 wt% H2SO4. Bring the solution up to the 1L mark, ensuring complete dissolution of the solid, and mix well to obtain the desired 40mg/L concentration of iron.