Calculating Temperature Decrease

Oct 13, 2025 by wbrum.org 115 views

Understanding the Problem

In this problem, we are tasked with calculating the decrease in temperature (in Celsius) when 2.00 L of a gas at 21.0 °C is compressed to 1.00 L. This problem involves the application of the ideal gas law and the concept of adiabatic processes.

The Ideal Gas Law

The ideal gas law is a fundamental principle in chemistry that describes the behavior of ideal gases. It is expressed by the equation:

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 gas constant
T is the temperature of the gas in Kelvin

Adiabatic Processes

An adiabatic process is a thermodynamic process in which no heat is transferred between the system and its surroundings. In an adiabatic process, the temperature of the gas changes as the volume of the gas changes.

Calculating Temperature Decrease

To calculate the decrease in temperature, we can use the following equation:

T1 / T2 = (V2 / V1)^(γ - 1)

where:

T1 is the initial temperature of the gas
T2 is the final temperature of the gas
V1 is the initial volume of the gas
V2 is the final volume of the gas
γ is the adiabatic index, which is approximately 1.4 for diatomic gases

Given Values

Initial volume (V1) = 2.00 L
Final volume (V2) = 1.00 L
Initial temperature (T1) = 21.0 °C = 294.15 K
Adiabatic index (γ) = 1.4

Substituting Values

Substituting the given values into the equation, we get:

T2 = T1 * (V1 / V2)^(γ - 1) = 294.15 K * (2.00 L / 1.00 L)^(1.4 - 1) = 294.15 K * (2.00 L / 1.00 L)^0.4 = 294.15 K * 1.319 = 388.51 K

Calculating Temperature Decrease

To calculate the temperature decrease, we subtract the final temperature from the initial temperature:

ΔT = T1 - T2 = 294.15 K - 388.51 K = -94.36 K

Converting to Celsius

To convert the temperature decrease from Kelvin to Celsius, we subtract 273.15 from the temperature decrease:

ΔT (°C) = -94.36 K - 273.15 = -367.51 °C

Conclusion

In this problem, we calculated the decrease in temperature when 2.00 L of a gas at 21.0 °C is compressed to 1.00 L. We used the ideal gas law and the concept of adiabatic processes to derive the equation for calculating the temperature decrease. The final answer is a temperature decrease of -367.51 °C.

Problem #1: Calculating Temperature Decrease in Compressed Gas Solution

Parameter	Value
Initial Volume (V1)	2.00 L
Final Volume (V2)	1.00 L
Initial Temperature (T1)	294.15 K
Adiabatic Index (γ)	1.4
Final Temperature (T2)	388.51 K
Temperature Decrease (ΔT)	-94.36 K
Temperature Decrease (ΔT) in °C	-367.51 °C

Key Takeaways

The ideal gas law is a fundamental principle in chemistry that describes the behavior of ideal gases.
Adiabatic processes are thermodynamic processes in which no heat is transferred between the system and its surroundings.
The temperature decrease can be calculated using the equation T2 = T1 * (V1 / V2)^(γ - 1).
The temperature decrease can be converted from Kelvin to Celsius by subtracting 273.15 from the temperature decrease.
Problem #1: Calculating Temperature Decrease in Compressed Gas - Q&A ===========================================================

Understanding the Problem

Q&A Session

Q: What is the ideal gas law?

A: The ideal gas law is a fundamental principle in chemistry that describes the behavior of ideal gases. It is expressed by the equation 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 gas constant, and T is the temperature of the gas in Kelvin.

Q: What is an adiabatic process?

A: An adiabatic process is a thermodynamic process in which no heat is transferred between the system and its surroundings. In an adiabatic process, the temperature of the gas changes as the volume of the gas changes.

Q: How do I calculate the temperature decrease?

A: To calculate the temperature decrease, you can use the equation T2 = T1 * (V1 / V2)^(γ - 1), where T1 is the initial temperature of the gas, T2 is the final temperature of the gas, V1 is the initial volume of the gas, V2 is the final volume of the gas, and γ is the adiabatic index.

Q: What is the adiabatic index?

A: The adiabatic index is a constant that depends on the type of gas. For diatomic gases, the adiabatic index is approximately 1.4.

Q: How do I convert the temperature decrease from Kelvin to Celsius?

A: To convert the temperature decrease from Kelvin to Celsius, you subtract 273.15 from the temperature decrease.

Q: What is the final answer to the problem?

A: The final answer to the problem is a temperature decrease of -367.51 °C.

Q: Can I use this equation to calculate the temperature decrease for any gas?

A: Yes, you can use this equation to calculate the temperature decrease for any gas, as long as you know the initial and final volumes, temperatures, and adiabatic index.

Q: What are some common applications of the ideal gas law and adiabatic processes?

A: The ideal gas law and adiabatic processes have many common applications in chemistry and physics, including the calculation of gas pressures, volumes, and temperatures, as well as the design of engines, compressors, and other devices that involve the compression and expansion of gases.

Q: Can I use this equation to calculate the temperature decrease for a gas that is not ideal?

A: No, this equation is only applicable to ideal gases. For real gases, you would need to use a more complex equation that takes into account the non-ideal behavior of the gas.

Q: What are some common mistakes to avoid when using this equation?

A: Some common mistakes to avoid when using this equation include:

Using the wrong units for the variables
Failing to account for the adiabatic index
Using the equation for a gas that is not ideal
Failing to convert the temperature decrease from Kelvin to Celsius

Q: Can I use this equation to calculate the temperature decrease for a gas that is at a constant pressure?

A: No, this equation is only applicable to adiabatic processes, which involve a change in volume. If the gas is at a constant pressure, you would need to use a different equation to calculate the temperature decrease.

Q: What are some common applications of the ideal gas law and adiabatic processes in real-world scenarios?

A: The ideal gas law and adiabatic processes have many common applications in real-world scenarios, including:

The design of engines and compressors
The calculation of gas pressures and volumes in industrial processes
The design of refrigeration systems
The calculation of gas temperatures and pressures in aerospace applications

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston?

A: Yes, you can use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston, as long as you know the initial and final volumes, temperatures, and adiabatic index.

Q: What are some common mistakes to avoid when using this equation in real-world scenarios?

A: Some common mistakes to avoid when using this equation in real-world scenarios include:

Failing to account for the adiabatic index
Using the equation for a gas that is not ideal
Failing to convert the temperature decrease from Kelvin to Celsius
Failing to consider the effects of friction and other non-ideal factors on the gas behavior.

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a fixed volume?

A: No, this equation is only applicable to adiabatic processes, which involve a change in volume. If the gas is in a container with a fixed volume, you would need to use a different equation to calculate the temperature decrease.

Q: What are some common applications of the ideal gas law and adiabatic processes in engineering and technology?

A: The ideal gas law and adiabatic processes have many common applications in engineering and technology, including:

The design of engines and compressors
The calculation of gas pressures and volumes in industrial processes
The design of refrigeration systems
The calculation of gas temperatures and pressures in aerospace applications

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston and a fixed temperature?

A: No, this equation is only applicable to adiabatic processes, which involve a change in volume. If the gas is in a container with a fixed temperature, you would need to use a different equation to calculate the temperature decrease.

Q: What are some common mistakes to avoid when using this equation in engineering and technology?

A: Some common mistakes to avoid when using this equation in engineering and technology include:

Failing to account for the adiabatic index
Using the equation for a gas that is not ideal
Failing to convert the temperature decrease from Kelvin to Celsius
Failing to consider the effects of friction and other non-ideal factors on the gas behavior.

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston and a variable temperature?

A: Yes, you can use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston and a variable temperature, as long as you know the initial and final volumes, temperatures, and adiabatic index.

Q: What are some common applications of the ideal gas law and adiabatic processes in scientific research?

A: The ideal gas law and adiabatic processes have many common applications in scientific research, including:

The study of gas behavior in high-temperature and high-pressure environments
The study of gas behavior in microgravity environments
The study of gas behavior in complex systems and networks
The study of gas behavior in biological systems and organisms.

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a fixed volume and a variable temperature?

Q: What are some common mistakes to avoid when using this equation in scientific research?

A: Some common mistakes to avoid when using this equation in scientific research include:

Failing to account for the adiabatic index
Using the equation for a gas that is not ideal
Failing to convert the temperature decrease from Kelvin to Celsius
Failing to consider the effects of friction and other non-ideal factors on the gas behavior.

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston and a variable temperature, and is also subject to external forces and torques?

A: Yes, you can use this equation to calculate the temperature decrease for a gas that is in a container with a movable piston and a variable temperature, and is also subject to external forces and torques, as long as you know the initial and final volumes, temperatures, and adiabatic index.

Q: What are some common applications of the ideal gas law and adiabatic processes in environmental science and conservation?

A: The ideal gas law and adiabatic processes have many common applications in environmental science and conservation, including:

The study of gas behavior in the atmosphere and oceans
The study of gas behavior in ecosystems and biological systems
The study of gas behavior in soil and groundwater systems
The study of gas behavior in urban and industrial environments.

Q: Can I use this equation to calculate the temperature decrease for a gas that is in a container with a fixed volume and a variable temperature, and is also subject to external forces and torques?

Q: What are some common mistakes to avoid when using this equation in environmental science and conservation?

A: Some common mistakes to avoid when