Chemistry

Charles's Law Calculator

Calculate gas volume or temperature changes using Charles's Law (V₁/T₁ = V₂/T₂) for ideal gases at constant pressure.

Solve for
Temperature unit
L
K
K
Final Volume (V₂)
3.00 L
Initial Volume (V₁)
2.00 L
Initial Temperature (T₁)
300.00 K
Final Volume (V₂)
3.00 L
Final Temperature (T₂)
450.00 K

Charles's Law assumes constant pressure and an ideal gas. Temperature must be in absolute units (Kelvin) for calculations, but you can input in any unit.

What is Charles's Law?

Charles's Law describes the relationship between the volume and temperature of a gas at constant pressure. It states that the volume of a gas is directly proportional to its absolute temperature when pressure remains constant.

Formula

V1T1=V2T2\frac{V_1}{T_1} = \frac{V_2}{T_2}

Where:

  • V₁ = Initial volume
  • T₁ = Initial temperature (in Kelvin)
  • V₂ = Final volume
  • T₂ = Final temperature (in Kelvin)

Solving for each variable

V2=V1×T2T1T2=V2×T1V1V1=V2×T1T2T1=V1×T2V2\begin{aligned} V_2 &= \frac{V_1 \times T_2}{T_1} \\[0.5em] T_2 &= \frac{V_2 \times T_1}{V_1} \\[0.5em] V_1 &= \frac{V_2 \times T_1}{T_2} \\[0.5em] T_1 &= \frac{V_1 \times T_2}{V_2} \end{aligned}

Important notes

  • Temperature must be in absolute units: Charles's Law requires temperature in Kelvin. This calculator automatically converts Celsius or Fahrenheit to Kelvin for calculations.
  • Constant pressure: The law only applies when pressure remains constant.
  • Ideal gas assumption: Real gases may deviate from this relationship at extreme conditions.

Temperature conversions

FromTo Kelvin
Celsius (°C)K = °C + 273.15
Fahrenheit (°F)K = (°F - 32) × 5/9 + 273.15

Example

A gas occupies 2.0 L at 300 K. What volume will it occupy at 450 K?

V2=V1×T2T1V2=2.0 L×450 K300 KV2=3.0 L\begin{aligned} V_2 &= \frac{V_1 \times T_2}{T_1} \\[0.5em] V_2 &= \frac{2.0 \text{ L} \times 450 \text{ K}}{300 \text{ K}} \\[0.5em] V_2 &= 3.0 \text{ L} \end{aligned}

Real-world applications

  • Hot air balloons: Heating air causes it to expand, making the balloon rise
  • Car engines: Combustion gases expand as temperature increases
  • Weather balloons: Volume changes as balloons rise through different temperatures
  • Refrigeration: Understanding gas behavior in cooling systems