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Ch.2 - Atoms & Elements
Chapter 2, Problem 93c

What is the amount, in moles, of each elemental sample? a. 23.2 g Kr

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1
Identify the molar mass of krypton (Kr) from the periodic table. The molar mass of Kr is approximately 83.8 g/mol.
Use the formula for moles: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \).
Substitute the given mass of krypton (23.2 g) and the molar mass of krypton (83.8 g/mol) into the formula.
Calculate the division to find the number of moles of krypton.
The result will give you the amount of krypton in moles.

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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 krypton (Kr) is approximately 83.8 g/mol, which is essential for converting grams to moles.
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Conversion from Grams to Moles

To find the number of moles from a given mass in grams, the formula used is: moles = mass (g) / molar mass (g/mol). This relationship allows chemists to relate the mass of a substance to the amount of substance in moles, facilitating stoichiometric calculations in chemical reactions.
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Stoichiometry

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