Caluculate the mass of ferrous ammonium sulfate (Fe(NH4)2(SO4)2.6H2O) you would need to add to a 4.0 mL volumetric flask to make a solution that is 75 ppm.
I've already identified that Fe is 14.24% of the Mohr's salt, but how would the conversion of that go to ppm? Ppm is mg/L, correct?
Yes, ppm is mg/L. Do you really man 4.0 mL? That isn't much volume and I didn't even know they made 4.0 mL volumetric flasks. So 75 ppm will be 75 mg/L or
75 x 4/1000 = 0.3 mg Fe.
0.3 mg Fe x (molar mass Mohr's salt/atomic mass Fe) =
Its some randomly generated question in preparation for a lab with normal sized vol. flasks. But yes, I agree, that would be a bit awkward to have a 4.0 mL flask. Haha
Can explain the unit conversions in the 75 x 4/1000 you posted?
You want 75 ppm. That is 75 mg/L. But you don't need a L; you need only 4 mL so convert 75 mg/L to ?mg/4 mL and that is 75 x 4/1000 = ? mg in 4 mL.
To calculate the mass of ferrous ammonium sulfate (Fe(NH4)2(SO4)2.6H2O) needed to make a solution that is 75 ppm in a 4.0 mL volumetric flask, you need to follow these steps:
1. Understand the definition of parts per million (ppm): Ppm represents the number of parts of a solute (in this case, mass) per million parts of the total solution (in this case, volume). Ppm can also be expressed as mg/L since 1 mg/L is equivalent to 1 ppm.
2. Calculate the volume of the solution in liters: The given volume is 4.0 mL. To convert it to liters, divide by 1000: 4.0 mL ÷ 1000 mL/L = 0.004 L.
3. Convert ppm to mg/L: Since 1 ppm is equivalent to 1 mg/L, we can directly use ppm as mg/L in this case. Thus, 75 ppm = 75 mg/L.
4. Determine the mass of ferrous ammonium sulfate: The molecular weight of ferrous ammonium sulfate (Fe(NH4)2(SO4)2.6H2O) can be calculated as follows:
Fe (55.845 g/mol) + 2(NH4) (2 × 18.038 g/mol) + 2(SO4) (2 × 96.062 g/mol) + 6(H2O) (6 × 18.015 g/mol) = 392.138 g/mol
So, the molar mass of ferrous ammonium sulfate is 392.138 g/mol.
5. Calculate the mass needed: Using the equation ppm = (mass of solute ÷ volume of solution) × 10^6, we can rearrange it to find the mass:
mass of solute = (ppm ÷ 10^6) × volume of solution
mass of solute = (75 mg/L ÷ 10^6) × 0.004 L
mass of solute = 0.0003 g or 0.3 mg
Therefore, you would need to add approximately 0.3 mg of ferrous ammonium sulfate to the 4.0 mL volumetric flask to make a solution that is 75 ppm.