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Ch.3 - Chemical Reactions and Reaction Stoichiometry
All textbooksBrown 14th EditionCh.3 - Chemical Reactions and Reaction StoichiometryProblem 92a
Chapter 3, Problem 92a

(a) One molecule of the antibiotic penicillin G has a mass of 5.342×10-21 g. What is the molar mass of penicillin G?

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Understand that the molar mass of a substance is the mass of one mole of its molecules, expressed in grams per mole (g/mol).
Recall that Avogadro's number, approximately 6.022 × 10^23, is the number of molecules in one mole of a substance.
To find the molar mass, multiply the mass of a single molecule by Avogadro's number. This will convert the mass from grams per molecule to grams per mole.
Set up the calculation: Molar mass = (mass of one molecule) × (Avogadro's number).
Substitute the given values into the equation: Molar mass = (5.342 × 10^-21 g/molecule) × (6.022 × 10^23 molecules/mol).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molar Mass

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 masses of all the atoms in a molecule. For example, the molar mass of water (H2O) is approximately 18.02 g/mol, derived from 2 hydrogen atoms and 1 oxygen atom.
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Avogadro's Number

Avogadro's number, approximately 6.022 × 10²³, is the number of particles (atoms, molecules, or ions) in one mole of a substance. This constant allows chemists to convert between the number of particles and the amount of substance in moles, facilitating calculations involving chemical reactions and stoichiometry.
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Unit Conversion

Unit conversion is the process of converting a quantity expressed in one set of units to another set of units. In chemistry, this often involves converting mass to moles using molar mass or converting between grams and kilograms. Understanding how to perform these conversions is essential for solving problems related to chemical quantities.
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Related Practice
Textbook Question

Very small semiconductor crystals, composed of approximately 1000 to 10,000 atoms, are called quantum dots. Quantum dots made of the semiconductor CdSe are now being used in electronic reader and tablet displays because they emit light efficiently and in multiple colors, depending on dot size. The density of CdSe is 5.82 g/cm3. (a) What is the mass of one 2.5-nm CdSe quantum dot?

Textbook Question

Very small semiconductor crystals, composed of approximately 1000 to 10,000 atoms, are called quantum dots. Quantum dots made of the semiconductor CdSe are now being used in electronic reader and tablet displays because they emit light efficiently and in multiple colors, depending on dot size. The density of CdSe is 5.82 g/cm3. (c) What is the mass of one 6.5-nm CdSe quantum dot?

Textbook Question

Very small semiconductor crystals, composed of approximately 1000 to 10,000 atoms, are called quantum dots. Quantum dots made of the semiconductor CdSe are now being used in electronic reader and tablet displays because they emit light efficiently and in multiple colors, depending on dot size. The density of CdSe is 5.82 g/cm3. (e) If you wanted to make one 6.5-nm dot from multiple 2.5-nm dots, how many 2.5-nm dots would you need, and how many CdSe formula units would be left over, if any?

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Textbook Question

(b) Hemoglobin, the oxygen-carrying protein in red blood cells, has four iron atoms per molecule and contains 0.340% iron by mass. Calculate the molar mass of hemoglobin.

Textbook Question
Cinnamaldehyde is a compound that is responsible for the characteristic aroma of cinnamon. It contains 81.79% C, 6.10% H, and the remaining is oxygen. Its molar mass is 132 g/mol. Determine its molecular formula.
Textbook Question
The fluoride ion reacts with water to produce HF. (a) Write out the chemical equation for this reaction.