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

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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.

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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). 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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