Chapter 3: Problem 58
Chemical analysis shows that the oxygen-carrying protein hemoglobin is 0.34 percent Fe by mass. What is the minimum possible molar mass of hemoglobin? The actual molar mass of hemoglobin is about \(65,000 \mathrm{~g}\). How would you account for the discrepancy between your minimum value and the experimental value?
Short Answer
Expert verified
The minimum molar mass of hemoglobin is approximately 16,393 g/mol, differing from the actual 65,000 g/mol due to structural complexity and multiple iron atoms.
Step by step solution
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Iron Content in Hemoglobin
Hemoglobin is a complex protein that plays a crucial role in transporting oxygen throughout the body. One of its most significant components is iron. The presence of iron is essential because it binds oxygen molecules, enabling hemoglobin to function efficiently. In chemical analysis, hemoglobin is found to be 0.34% iron by mass. This means that in every 100 grams of hemoglobin, there are 0.34 grams of iron. This percentage is critically important when determining the molar mass of hemoglobin.
Iron's role isn't merely passive but pivotal, anchoring oxygen and ensuring it can be transported where needed. Understanding the proportion of iron helps to unveil some of the molecular structure and functioning of hemoglobin. This information is useful when conducting experiments and making further calculations.
Iron's role isn't merely passive but pivotal, anchoring oxygen and ensuring it can be transported where needed. Understanding the proportion of iron helps to unveil some of the molecular structure and functioning of hemoglobin. This information is useful when conducting experiments and making further calculations.
Molar Mass Calculation
Calculating the molar mass of hemoglobin based on its iron content involves several steps. It begins with calculating the number of moles of iron present in a given amount of hemoglobin. The molar mass of iron is approximately 55.85 g/mol. To find the number of moles in 0.34 grams of iron, you use the formula:
\[ \text{Number of moles of iron} = \frac{0.34 \text{ grams}}{55.85 \text{ g/mol}} \approx 0.0061 \text{ moles} \]
This calculation helps determine how many moles of hemoglobin correspond to iron content, assuming each hemoglobin molecule contains one atom of iron.
Next, we find the minimum possible molar mass of hemoglobin. Since 0.0061 moles of iron represent 100 grams of hemoglobin, the molar mass calculation for hemoglobin is:
\[ \text{Minimum molar mass of hemoglobin} = \frac{100}{0.0061} \approx 16,393 \text{ g/mol} \]
This value only provides a minimum estimate, assuming each hemoglobin unit carries one iron atom.
\[ \text{Number of moles of iron} = \frac{0.34 \text{ grams}}{55.85 \text{ g/mol}} \approx 0.0061 \text{ moles} \]
This calculation helps determine how many moles of hemoglobin correspond to iron content, assuming each hemoglobin molecule contains one atom of iron.
Next, we find the minimum possible molar mass of hemoglobin. Since 0.0061 moles of iron represent 100 grams of hemoglobin, the molar mass calculation for hemoglobin is:
\[ \text{Minimum molar mass of hemoglobin} = \frac{100}{0.0061} \approx 16,393 \text{ g/mol} \]
This value only provides a minimum estimate, assuming each hemoglobin unit carries one iron atom.
Chemical Analysis of Proteins
The chemical analysis of proteins like hemoglobin helps scientists better understand their structure and function. Proteins are complex molecules made from chains of amino acids, and chemical analysis allows researchers to dissect these chains to identify key components such as iron. Techniques like mass spectrometry and spectroscopy are often used.
Understanding the role and quantity of elements like iron within a protein helps in revealing how these proteins interact within biological systems. The specifics of protein chemistry are integral in fields like medicine and biotechnology, where insights into protein structures can lead to new therapies and advancements in diagnostics.
Understanding the role and quantity of elements like iron within a protein helps in revealing how these proteins interact within biological systems. The specifics of protein chemistry are integral in fields like medicine and biotechnology, where insights into protein structures can lead to new therapies and advancements in diagnostics.
Discrepancy in Experimental Values
A calculated molar mass of hemoglobin based on iron content gives a value around 16,393 g/mol as a minimum. In contrast, experimental methods measure hemoglobin's molar mass to be about 65,000 g/mol.
This significant difference, or discrepancy, arises because the initial calculations oversimplify hemoglobin's structure. Hemoglobin is not only composed of single iron atoms but includes multiple iron atoms per molecule, complex tertiary and quaternary structures, as well as various amino acids linked in precise sequences.
Discrepancies in values often underline the necessity for understanding the broader context of chemical structures and molecular chemistry. They highlight how theoretical calculations may need adjustments when considering practical, real-world data and analyses. Students and scientists must remain prudent and mindful of these differences when interpreting calculated results versus experimental findings.
This significant difference, or discrepancy, arises because the initial calculations oversimplify hemoglobin's structure. Hemoglobin is not only composed of single iron atoms but includes multiple iron atoms per molecule, complex tertiary and quaternary structures, as well as various amino acids linked in precise sequences.
Discrepancies in values often underline the necessity for understanding the broader context of chemical structures and molecular chemistry. They highlight how theoretical calculations may need adjustments when considering practical, real-world data and analyses. Students and scientists must remain prudent and mindful of these differences when interpreting calculated results versus experimental findings.
