Hemoglobin is \(6.0 \%\) heme \(\left(\mathrm{C}_{34} \mathrm{H}_{32} \mathrm{FeN}_{4} \mathrm{O}_{4}\right)\) by mass. To remove the heme, hemoglobin is treated with acetic acid and \(\mathrm{NaCl},\) which forms hemin \(\left(\mathrm{C}_{34} \mathrm{H}_{32} \mathrm{~N}_{4} \mathrm{O}_{4} \mathrm{FeCl}\right) .\) A blood sample from a crime scene contains \(0.65 \mathrm{~g}\) of hemoglobin. (a) How many grams of heme are in the sample? (b) How many moles of heme? (c) How many grams of Fe? (d) How many grams of hemin could be formed for a forensic chemist to measure?

Mass percentage helps us understand how much of a specific substance is present in a mixture or compound. In our problem, we see that hemoglobin is 6.0% heme by mass. This tells us that in every 100 grams of hemoglobin, there are 6 grams of heme.
To find the mass of heme in a specific sample, use the formula: mass of heme = total mass of hemoglobin × (percentage of heme / 100) In this case, for a 0.65 g blood sample: mass of heme = 0.65 g × (6.0 / 100) = 0.039 g.
This calculation lets us know how much heme is contained in the given hemoglobin sample.

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). To solve our exercise, we need the molar mass of heme (C_{34}H_{32}FeN_{4}O_{4}).
Use the atomic masses of the elements: -Carbon (C): 12.01 g/mol-Hydrogen (H): 1.01 g/mol-Iron (Fe): 55.85 g/mol-Nitrogen (N): 14.01 g/mol-Oxygen (O): 16.00 g/mol.
Calculate the molar mass of heme: molar mass of heme = (34 × 12.01) + (32 × 1.01) + 55.85 + (4 × 14.01) + (4 × 16.00) = 616.49 g/mol.
This information is crucial as it allows us to convert between mass and moles when dealing with chemical calculations.

Stoichiometry involves using balanced chemical equations to determine the relationships between reactants and products. Here, it helps us convert between moles of heme and moles of iron or hemin formed. Since heme has one iron (Fe) atom per molecule, the moles of heme equals the moles of iron. For a forensic chemist, using stoichiometry ensures precision in their measurements and calculations. For example, to find the mass of iron from the moles of heme, use the formula: mass of Fe = moles of heme × molar mass of Fe given the moles of heme = 6.32 × 10^{-5} mol and molar mass of Fe = 55.85 g/mol: mass of Fe = 6.32 × 10^{-5} mol × 55.85 g/mol = 0.00353 g.

Forensic chemistry applies chemical principles to solve crimes. In our problem, the forensic chemist analyzes hemoglobin to measure hemin, a substance that forms when hemoglobin is treated with acetic acid and NaCl.
This process can help determine the presence and amount of hemoglobin in a sample.
By calculating the mass of hemin produced, investigators can estimate the original hemoglobin content. This data is vital for forensic chemists in crime scene investigations, helping them gather evidence through chemical analysis. For instance, to find the mass of hemin formed, use moles of heme and molar mass of hemin:mass of hemin = moles of heme × molar mass of hemin. Here, moles of heme = 6.32 × 10^{-5} mol and molar mass of hemin = 651.94 g/mol: mass of hemin = 6.32 × 10^{-5} mol × 651.94 g/mol = 0.0412 g.
Understanding these chemical principles aids forensic chemists in accurate measurements, crucial for criminal investigations.