Determination of iron in serum by spectrophotometeic method

Question

Assignment:

Q1.In the laboratory you have prepared various reagents for your experiments. briefly describe the preparation of 3.00 L of 0.150 M H₃PO₄ from concentrated commercial reagent. This reagent if 86.0% H₃PO₄ and has a density of 1.84g/mL. The molar mass of H₃PO₄ is 97.995 g/mol

Q2. The following data were obtained for the determination of iron in serum by a spectrophotometeic method. Assuming the validity of Beer's Law for the experiment calcualte the concentration of iron in serum..
Sample    Absorbance at 562 nm in 1.000 cm cell
Blank    0.038
3.00 µg Fe standard    0.329
Serum sample    0.219

Q3. What pH do you expect if you mix 25.mL of 0.2M NaOH with 50.0 mL of 0.15 M HNO₃ and then dilute to 250.0mL in a volumetric flask?

Provide complete and step by step solution for the question and show calculations and use formulas.