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Ch.7 Chemical Quantities and Reactions
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 7, Problem 79c

Using the models of the molecules (black = C, white = H, yellow = S, green = Cl), determine each of the following for models of compounds 1 and 2:

d. number of moles in 10.0 g

Verified step by step guidance
1
Step 1: Identify the molecular formulas of the compounds based on the models provided. For compound 1 (top model), the molecule consists of two yellow spheres (sulfur) and one red sphere (oxygen), indicating the formula is likely SO2. For compound 2 (bottom model), the molecule consists of four black spheres (carbon) and eight white spheres (hydrogen), indicating the formula is likely C4H8.
Step 2: Determine the molar mass of each compound. For SO2, calculate the molar mass by summing the atomic masses of sulfur (32.07 g/mol) and oxygen (16.00 g/mol × 2). For C4H8, calculate the molar mass by summing the atomic masses of carbon (12.01 g/mol × 4) and hydrogen (1.008 g/mol × 8).
Step 3: Use the formula for moles: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \). Substitute the given mass (10.0 g) and the molar mass calculated for each compound into the formula.
Step 4: Perform the calculation for each compound separately to determine the number of moles in 10.0 g of SO2 and C4H8. Ensure units are consistent (grams for mass and g/mol for molar mass).
Step 5: Interpret the results to understand the number of moles present in 10.0 g of each compound. This will provide insight into the quantity of each substance in terms of moles.

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Key Concepts

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

Molecular Composition

Molecular composition refers to the types and numbers of atoms that make up a molecule. In the context of the question, understanding the molecular formulas of the compounds represented in the models is essential. For example, the black spheres represent carbon (C), white spheres represent hydrogen (H), yellow represents sulfur (S), and green represents chlorine (Cl). Identifying these components allows for the calculation of moles based on the molecular weight.
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Mole Concept

The mole concept is a fundamental principle in chemistry that relates the mass of a substance to the number of particles it contains. One mole of any substance contains Avogadro's number of entities (approximately 6.022 x 10²³). To determine the number of moles in a given mass (like 10.0 g), one must divide the mass by the molar mass of the substance, which is derived from its molecular composition.
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Molar Mass Calculation

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 atoms in a molecule. For the compounds in the question, determining the molar mass is crucial for calculating the number of moles in 10.0 g. This involves using the periodic table to find the atomic weights of carbon, hydrogen, sulfur, and chlorine, and applying them to the molecular formulas.
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