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Ch.6 - Gases
Chapter 6, Problem 59

Use the molar volume of a gas at STP to determine the volume (in L) occupied by 27.2 g of argon at STP.

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1
Identify the molar mass of argon (Ar) from the periodic table, which is approximately 39.95 g/mol.
Calculate the number of moles of argon using the formula: \( \text{moles of Ar} = \frac{\text{mass of Ar}}{\text{molar mass of Ar}} \). Substitute the given mass of argon (27.2 g) and its molar mass.
Recall that at standard temperature and pressure (STP), 1 mole of any ideal gas occupies 22.4 L.
Use the number of moles calculated in step 2 and multiply by the molar volume at STP (22.4 L/mol) to find the volume occupied by the argon gas.
Express the final volume in liters, ensuring that the units are consistent throughout the calculation.

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Key Concepts

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

Molar Volume of a Gas

The molar volume of a gas at standard temperature and pressure (STP) is the volume occupied by one mole of an ideal gas, which is approximately 22.4 liters. This value is crucial for converting between the mass of a gas and its volume, allowing for calculations involving the amount of substance in moles.
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Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For argon, the molar mass is about 39.95 g/mol. Understanding molar mass is essential for converting the mass of a gas to moles, which is a necessary step in determining its volume at STP.
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Stoichiometry

Stoichiometry is the area of chemistry that deals with the relationships between the quantities of reactants and products in chemical reactions. In this context, it involves using the molar mass and molar volume to relate the mass of argon to its volume at STP, enabling the calculation of how much space the gas occupies.
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