Solve V₁/T₁ = V₂/T₂ | Volume & Temperature of Gas at Constant Pressure
Result
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📝 Step-by-step solution
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💡 Charles's Law: V₁/T₁ = V₂/T₂ at constant pressure | Temperature must be in Kelvin (K = °C + 273.15)
📖 What is Charles's Law?
Charles's Law (also known as the Law of Volumes) states that at constant pressure,
the volume of a fixed amount of gas is directly proportional to its absolute temperature
(measured in Kelvin). As the temperature of a gas increases, its volume increases proportionally — and vice versa.
The law was first published by French scientist Jacques Charles in 1787 and later refined by
Joseph Louis Gay-Lussac in 1802. It is one of the three fundamental gas laws, along with
Boyle's Law (pressure-volume) and Gay-Lussac's Law (pressure-temperature).
V₁ / T₁ = V₂ / T₂ (at constant P and n)
Where:
• V₁ = Initial volume (L or mL)
• T₁ = Initial absolute temperature (K)
• V₂ = Final volume (L or mL)
• T₂ = Final absolute temperature (K)
Result: The balloon expands to 2.67 L when heated from 300 K to 400 K.
🌡️ Why Kelvin Matters
Charles's Law requires temperature in Kelvin, not Celsius or Fahrenheit.
This is because the Kelvin scale starts at absolute zero (−273.15 °C),
where the volume of an ideal gas theoretically becomes zero. Using Celsius would give incorrect results
(e.g., 0 °C is 273.15 K, not zero).
K = °C + 273.15 °C = K − 273.15
💡 Common Uses of Charles's Law
Hot air balloons: Heating air causes it to expand and become less dense, providing lift.
Weather balloons: As they rise, pressure decreases and temperature drops, causing expansion.
Car engines: Air-fuel mixture expands when ignited, pushing the piston.
Baking: Bread and cakes rise because gas bubbles expand when heated.
Tire pressure: Tires appear more inflated in summer due to thermal expansion.
Refrigerators and AC: Gas compression and expansion cycles rely on Charles's Law.
⚠️ Limitations & Assumptions
📌 Important Notes
Pressure must be constant throughout the process.
Temperature must be in Kelvin — using Celsius or Fahrenheit will give wrong answers.
Assumes the gas behaves ideally — real gases deviate at very high pressure or low temperature.
The amount of gas (moles) must be constant — no gas leaks in or out.
Volume units must be consistent (both in L, or both in mL).
Results are theoretical — real-world conditions may introduce slight variations.
📚 Sources & References
Authoritative Sources
OpenStax — Chemistry 2e, Chapter 9: Gases
NIST — Thermodynamic Properties of Gases
Khan Academy — Ideal Gas Laws
CRC Handbook of Chemistry and Physics
❓ Frequently Asked Questions
Why does Charles's Law use Kelvin?
Kelvin is an absolute temperature scale starting at absolute zero (−273.15 °C),
where gas volume theoretically becomes zero. Using Celsius would give incorrect proportionality
because 0 °C is not absolute zero.
What is the difference between Charles's Law and Gay-Lussac's Law?
Charles's Law relates volume and temperature at constant pressure (V₁/T₁ = V₂/T₂).
Gay-Lussac's Law relates pressure and temperature at constant volume (P₁/T₁ = P₂/T₂).
Can Charles's Law be used for liquids or solids?
No — Charles's Law applies specifically to gases. Liquids and solids have very different
thermal expansion behavior described by coefficients of thermal expansion.
What happens if temperature doubles?
If temperature (in Kelvin) doubles at constant pressure, the volume also doubles.
For example, 2 L at 300 K becomes 4 L at 600 K.
Is Charles's Law valid at very low temperatures?
Only approximately. Real gases deviate from ideal behavior near their boiling point
and at very low temperatures. Charles's Law is exact only for an ideal gas.
This Charles's Law Calculator is provided for informational and educational purposes only.
Results are based on the ideal gas approximation and assume constant pressure and constant amount of gas.
Real gases deviate from ideal behavior at high pressures and low temperatures.
Always verify critical calculations with authoritative sources or a qualified instructor.
Online Calculator Zone is not responsible for any decisions made based on these results.