What is the amount, in moles, of each elemental sample? a. 11.8 g Ar b. 3.55 g Zn c. 26.1 g Ta d. 0.211 g Li

Name: Chemistry: A Molecular Approach
Author: Tro
ISBN: 9780134112831

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Identify the molar mass of argon (Ar) from the periodic table, which is approximately 39.95 g/mol.

Use the formula for moles: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \).

Substitute the given mass of argon (11.8 g) and its molar mass (39.95 g/mol) into the formula.

Calculate the division to find the number of moles of argon.

Express the result in moles, ensuring the units are correct.

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). For elements, it corresponds to the atomic weight found on the periodic table. For example, the molar mass of argon (Ar) is approximately 39.95 g/mol, which is essential for converting grams of an element to moles.

Conversion from Grams to Moles

To convert grams of a substance to moles, the formula used is: moles = mass (g) / molar mass (g/mol). This relationship allows chemists to quantify the amount of substance in a sample, facilitating calculations in stoichiometry and chemical reactions.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. Understanding stoichiometry is crucial for determining how much of each substance is involved in a reaction, which is often based on the mole concept and molar mass calculations.

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