Textbook Question
Cyclohexane, C6H12, is an important starting material used in the industrial synthesis of nylon. Each carbon has four covalent bonds, two to hydrogen and two to other carbons. Draw the structural formula of cyclohexane.
Ch.23 - Organic and Biological Chemistry
Chapter 23, Problem 136
Cytochrome c is an important enzyme found in the cells of all aerobic organisms. Elemental analysis of cytochrome c shows that it contains 0.43% iron. What is the minimum molecular weight of this enzyme?
Verified step by step guidance1
Step 1: Understand that the problem is asking for the minimum molecular weight of cytochrome c based on its iron content. This means we need to find the smallest possible molecular weight that would allow for 0.43% of the enzyme to be iron.
Step 2: Recognize that the percentage by mass of iron in cytochrome c is given as 0.43%. This means that in 100 grams of cytochrome c, there are 0.43 grams of iron.
Step 3: Use the molar mass of iron (Fe), which is approximately 55.85 g/mol, to determine the number of moles of iron in 0.43 grams. This is done by dividing the mass of iron by its molar mass: \( \text{moles of Fe} = \frac{0.43 \text{ g}}{55.85 \text{ g/mol}} \).
Step 4: Since the problem asks for the minimum molecular weight, assume that there is only one atom of iron per molecule of cytochrome c. This means the moles of iron calculated in Step 3 correspond to the moles of cytochrome c.
Step 5: Calculate the minimum molecular weight of cytochrome c by using the formula: \( \text{Molecular weight of cytochrome c} = \frac{\text{mass of cytochrome c}}{\text{moles of cytochrome c}} \). Use 100 grams as the mass of cytochrome c and the moles of cytochrome c from Step 4.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecular Weight
Molecular weight, or molar mass, is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic weights of all atoms in a molecule. Understanding molecular weight is crucial for determining the amount of a substance in a chemical reaction and for converting between moles and grams.
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Weight Conversion Example
Percent Composition
Percent composition refers to the percentage by mass of each element in a compound. It is calculated by dividing the mass of the element in one mole of the compound by the total molar mass of the compound, then multiplying by 100. This concept is essential for analyzing the elemental makeup of compounds and for solving problems related to molecular weight.
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Stoichiometry
Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced in a reaction. In this context, stoichiometry is important for calculating the minimum molecular weight of cytochrome c based on its iron content.
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Related Practice
Textbook Question
Isooctane, the substance in gasoline from which the term octane rating derives, has the formula C8H18. Each carbon has four covalent bonds, and the atoms are connected in the sequence shown. Draw the complete structural formula of isooctane.
Textbook Question
Fructose, C6H12O6, is the sweetest naturally occurring sugar and is found in many fruits and berries. Each carbon has four covalent bonds, each oxygen has two covalent bonds, each hydrogen has one covalent bond, and the atoms are connected in the sequence shown. Draw the complete struc-tural formula of fructose.