Chapter 11: Problem 99
Use the ideal gas law to show that the molar volume of a gas at STP is \(22.4 \mathrm{~L}\).
Short Answer
Expert verified
At STP, standard temperature is taken as 273.15K and standard pressure as 1 atm. Inserting these values into the ideal gas law (\(PV=nRT\)) and setting the number of moles to 1, we get the volume of 1 mole of gas is approximately 22.4 L.
Step by step solution
01
State the ideal gas law
The ideal gas law is an equation of state for a hypothetical ideal gas. It is a good approximation to the behavior of many gases under many conditions, although it has several limitations. The ideal gas law is usually stated as: \( PV = nRT \), where \( P \) is the pressure of the gas, \( V \) is the volume of the gas, \( n \) is the number of moles of the gas, \( R \) is the ideal gas constant, and \( T \) is the temperature of the gas.
02
Insert the STP conditions into the ideal gas law
At STP (Standard Temperature and Pressure), the defined conditions are \( 0^\circ\mathrm{C} \) for temperature, which is \( 273.15\mathrm{K} \), and \( 1\mathrm{atm} \) for pressure. The gas constant \( R \) is generally given as \( 0.0821\frac{\mathrm{L \cdot atm}}{\mathrm{K \cdot mol}} \). With \( n \) set to 1 mole for molar volume, the ideal gas law becomes: \( (1\mathrm{atm})V = (1\mathrm{mol})(0.0821\frac{\mathrm{L \cdot atm}}{\mathrm{K \cdot mol}})(273.15\mathrm{K}) \).
03
Calculate the volume of the gas at STP
To find the molar volume of the gas at STP, solve for \( V \) in the ideal gas law equation. Multiplying out the right-hand side of the equation we get: \( V = (0.0821\frac{\mathrm{L \cdot atm}}{\mathrm{K \cdot mol}})(273.15\mathrm{K}) \). By calculating this, we find that \( V \approx 22.4\mathrm{L} \), which is the molar volume of an ideal gas at STP.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
STP (Standard Temperature and Pressure)
Understanding STP is essential when working with gases in chemistry. STP refers to the condition under which the temperature is set to 0 degrees Celsius (273.15 Kelvin) and the pressure is 1 atmosphere (atm). These standardized conditions make calculations simpler and more uniform across different scenarios. At STP, behaviors of gases can be predicted more accurately using the ideal gas law, as it provides a common reference point.
The use of STP is widespread in the study of gases because it corresponds to 'standard' lab conditions, and therefore is helpful in allowing scientists and students to compare results from different experiments effectively. Being familiar with STP conditions also facilitates understanding of how gases will behave under different temperatures and pressures, a valuable aspect in various industrial and scientific applications.
The use of STP is widespread in the study of gases because it corresponds to 'standard' lab conditions, and therefore is helpful in allowing scientists and students to compare results from different experiments effectively. Being familiar with STP conditions also facilitates understanding of how gases will behave under different temperatures and pressures, a valuable aspect in various industrial and scientific applications.
Molar Volume
Molar volume is a term used to describe the volume occupied by one mole of a substance, usually a gas. At STP, the molar volume of any ideal gas is approximately 22.4 liters. This volume allows scientists and students to calculate how much space a known amount of gas will occupy under standard conditions, which is important for applications such as chemical reactions happening in closed systems, or industrial processes where the volume of gases needs to be controlled.
Understanding molar volume is also crucial for stoichiometry calculations in chemistry, where reactions often involve volumes of gases. With the molar volume known, predicting product volumes in gas-producing reactions becomes possible. This concept is part of the foundation for advanced chemistry education and helps in making real-world connections to theoretical knowledge.
Understanding molar volume is also crucial for stoichiometry calculations in chemistry, where reactions often involve volumes of gases. With the molar volume known, predicting product volumes in gas-producing reactions becomes possible. This concept is part of the foundation for advanced chemistry education and helps in making real-world connections to theoretical knowledge.
Chemistry Education
Chemistry education involves making complex concepts approachable and understandable for students. When introducing the ideal gas law and related concepts such as STP and molar volume, it's important to use clear explanations, relate them to real-world examples, and reinforce learning through practice. Chemistry is often taught using a combination of theoretical lessons, hands-on experiments, and problem-solving exercises to engage students and enhance their understanding.
Effective chemistry education relies on sequencing knowledge in a logical manner, beginning with easier concepts and building up to more advanced topics. This structured approach encourages the development of critical thinking skills and scientific literacy. Providing students with a strong foundation in understanding gases and the laws that govern their behavior underpins their ability to grasp more intricate chemical phenomena.
Effective chemistry education relies on sequencing knowledge in a logical manner, beginning with easier concepts and building up to more advanced topics. This structured approach encourages the development of critical thinking skills and scientific literacy. Providing students with a strong foundation in understanding gases and the laws that govern their behavior underpins their ability to grasp more intricate chemical phenomena.
Gas Constant
The gas constant, denoted by the symbol 'R', is fundamental in the field of thermodynamics and plays a pivotal role in the ideal gas law. It is a proportionality constant that relates the energy scale to the temperature scale and appears in the equation of state for an ideal gas. The value of R is derived from the conditions where one mole of an ideal gas at STP occupies 22.4 liters.
The constant is typically given as 0.0821 L·atm/K·mol for calculations at STP. Its value enables the bridging of macroscopic measurements (like pressure and volume) to the microscopic behavior of gas molecules. Knowledge of the gas constant is integral to performing calculations involving energy, work, and transformations in chemical reactions. Recognizing and correctly applying the gas constant is a key competency in advanced chemistry calculations.
The constant is typically given as 0.0821 L·atm/K·mol for calculations at STP. Its value enables the bridging of macroscopic measurements (like pressure and volume) to the microscopic behavior of gas molecules. Knowledge of the gas constant is integral to performing calculations involving energy, work, and transformations in chemical reactions. Recognizing and correctly applying the gas constant is a key competency in advanced chemistry calculations.