What is the Difference Between Boyle’s Law and Charles Law

The main difference between Boyle’s law and Charles’s law is that Boyle’s law relates the pressure and volume of a gas while keeping the temperature constant, whereas Charles’s law pertains to the relationship between the volume and temperature of a gas at constant pressure.

Boyle’s Law and Charles’s Law are fundamental principles in the field of gas physics, each describing how gases respond to changes in their surrounding conditions.

Key Areas Covered

1. What is Boyle’s Law  
      – Definition, Calculation, Applications
2. What is Charles Law
      – Definition, Calculation, Applications
3. Similarities Between Boyle’s Law and Charles’s Law
      – Outline of Common Features
4. Difference Between Boyle’s Law and Charles’s Law
      – Comparison of Key Differences
5. FAQ: Boyle’s Law and Charles Law
      – Frequently Asked Questions

Key Terms

Boyle’s Law, Charles Law

What is Boyle’s Law

Boyle’s Law can be traced back to the scientific experiments conducted by Robert Boyle in the mid-17th century. Boyle’s groundbreaking work focused on the relationship between the pressure and volume of a gas while holding the temperature constant. He used a J-shaped glass tube with mercury in the bottom to trap a fixed amount of air and a piston to vary the volume of the trapped air. By systematically altering the volume of the air and measuring the corresponding pressure, Boyle discovered that as the volume of the gas increased, the pressure decreased, and vice versa. The fundamental principle behind Boyle’s Law can be expressed mathematically as follows:

P₁ * V₁ = P₂ * V₂

Where:

P₁ and P₂ represent the initial and final pressures, respectively, in the same units of pressure (e.g., atmospheres, pascals, or torr).

V₁ and V₂ represent the initial and final volumes, respectively, typically in the same units of volume (e.g., liters, milliliters, or cubic centimeters).

This equation demonstrates that the product of the initial pressure and volume of a gas is equal to the product of the final pressure and volume as long as the temperature remains constant. In practical terms, it means that when the volume of a gas is reduced (V₂ < V₁), its pressure increases (P₂ > P₁), and when the volume is increased (V₂ > V₁), the pressure decreases (P₂ < P₁). The relationship between pressure and volume is inverse, illustrating that as one variable changes, the other changes in the opposite direction.

What are the Applications of Boyle’s Law

Boyle’s Law holds significant practical applications across various real-world contexts. In scuba diving, it’s crucial to understand how pressure changes with depth and its impact on scuba tank air volume to prevent decompression sickness. Weather balloons rely on Boyle’s Law to interpret atmospheric data as they ascend and experience pressure changes. Automotive airbags employ this law to rapidly expand and cushion during collisions. In laboratory equipment, it ensures accurate measurements and controlled reactions. In chemistry and industries, it aids in managing gas volumes and pressures for precise processes. Even in homebrewing and carbonation, Boyle’s Law is utilized to regulate carbon dioxide levels in beverages like beer and soda.

What is Charles Law

Jacques Charles, a French inventor and scientist, is often credited with the formulation of the law that now bears his name. Charles conducted experiments involving gases at various temperatures and observed a consistent pattern: as the temperature of a gas increased, its volume also increased proportionally. This relationship between temperature and volume provided a basis for Charles’s Law. Here, the gas is considered ideal.

Mathematical Formulation

Charles’s Law can be expressed mathematically as follows:

V₁/T₁ = V₂/T₂

Where:

V₁ and V₂ represent the initial and final volumes of the gas, respectively, typically in units of volume (e.g., liters or milliliters).

T₁ and T₂ represent the initial and final absolute temperatures of the gas, typically measured in Kelvin (K).

This equation illustrates that the ratio of the initial volume to the initial absolute temperature is equal to the ratio of the final volume to the final absolute temperature, provided that the pressure and the amount of gas remain constant. In practical terms, this means that as the temperature of a gas increases, its volume also increases, and as the temperature decreases, the volume decreases. The relationship between volume and temperature is direct, demonstrating that when one variable changes, the other changes in the same direction.

What are the Applications of Charles Law

Charles’s law finds practical applications in various real-world scenarios. In balloon flights, it explains the principles behind the ascent and descent of hot air balloons as the air inside expands and contracts with temperature changes. Cryonics and cryopreservation rely on Charles’s Law to regulate the volume and pressure of cryogenic gases for the storage of biological samples, organs, or bodies at extremely low temperatures.

HVAC systems use Charles’s Law to provide thermal comfort by controlling the expansion and contraction of air to maintain desired indoor temperatures. In industrial processes, the law ensures the safe release of excess pressure in gas storage tanks or equipment. Additionally, the food and beverage industry employs Charles’s Law to control the temperature and pressure of carbon dioxide gas for carbonating beverages like soda and beer. Scientific instruments such as gas chromatographs and mass spectrometers also utilize Charles’s Law to control the volume of gases involved in analytical processes.

Similarities Between Boyle’s Law and Charles Law

• Boyle’s and Charles’s laws are based on the assumption that gases behave as ideal gases.
• Both laws are expressed mathematically as simple proportionality relationships.
• Both Boyle’s and Charles’s laws assume that the amount of gas is held constant throughout the processes they describe.

Difference Between Boyle’s Law and Charles Law

Definition

Boyle’s law is a law that relates the pressure and volume of a gas while keeping the temperature constant, whereas Charle’s law is a law that pertains to the relationship between the volume and temperature of a gas at constant pressure.

Mathematical Equation

Boyle’s law is calculated as P1V1=P2V2, whereas Charle’s law is calculated as V1/T1 = V2/T2.

Constant

In Boyle’s law, temperature is kept constant, whereas in Charle’s law, pressure is kept constant.

FAQ: Boyle’s Law and Charles Law

What is common between Bolye’s law and Charle’s law?

Both laws deal with the temperature, pressure, and volume of ideal gasses.

Can Boyle’s law and Charle’s law be combined?

Together with Gay Lussac’s law, Boyle’s law, and Charles’s law form a combined equation. The combined law is called the combined gas law.

What is the difference between Boyle’s Law and Lussac’s law?

The primary difference between Boyle’s Law and Gay-Lussac’s Law is the gas property they relate to changes in pressure and temperature, respectively. Boyle’s Law describes the inverse relationship between the pressure and volume of a gas at constant temperature, while Gay-Lussac’s Law explains the direct relationship between the pressure and temperature of a gas at constant volume.

Conclusion

In brief, Boyle’s law relates the pressure and volume of a gas while keeping the temperature constant, whereas Charle’s law pertains to the relationship between the volume and temperature of a gas at constant pressure. Thus, this is the main difference between Boyle’s law and Charles law.

Reference:

1. “Boyle’s Law.” Byju’s.
2. “Charle’s Law.” Byju’s.

Image Courtesy:

1. “Boyles Law” By Krishnavedala – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Charles and Gay-Lussac’s Law animated” By NASA’s Glenn Research Center –  (Public Domain) via Commons Wikimedia