Charles's Law Calculator

Charles's law states that at constant pressure, gas volume is directly proportional to absolute temperature (Kelvin). Double the temperature, double the volume. Temperature MUST be in Kelvin.

💨 Gas Laws📐 V₁/T₁ = V₂/T₂🌡️ Constant Pressure

Initial Volume V₁ (L)

Initial Temperature T₁ (K)

Final Temperature T₂ (K)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Charles Law	—	V₁/T₁ = V₂/T₂	—
Final Volume	V₂	V₁ × T₂/T₁	L
Final Temperature	T₂	T₁ × V₂/V₁	K
Convert °C	T(K)	T(°C) + 273.15	K
Absolute Zero	0 K	= −273.15°C	K

Step-by-Step Examples

Example 1

Heating Gas

Gas at 273 K (0°C) has volume 5.00 L. Heated to 373 K (100°C) at constant P.

V₂ = V₁×T₂/T₁ = 5.00×373/273
V₂ = 6.83 L

✓ 6.83 L at 100°C

Example 2

Balloon in Freezer

Balloon at 298 K (25°C), 2.50 L placed in freezer at 253 K (-20°C).

V₂ = 2.50×253/298 = 2.12 L

✓ 2.12 L (shrinks in cold)

Example 3

Find Temperature

Gas at 300 K, 3.00 L must expand to 4.50 L. Find T₂.

T₂ = 300×4.50/3.00 = 450 K = 177°C

✓ Must be heated to 450 K (177°C)

Real-World Applications

🎈

Hot Air Balloons

Heating air reduces density; balloon rises when inside air is less dense than outside.

🌡️

Thermometers

Gas thermometers use volume change with temperature (Charles's law) to measure T.

✈️

Engine Design

Combustion products expand when heated, driving pistons. Charles's law describes this.

❄️

Cold Weather

Tires deflate in winter because air volume decreases with temperature at constant P.

Common Mistakes to Avoid

⚠️

Temperature must be in Kelvin

Charles's law requires absolute temperature. 0°C = 273.15 K. NEVER use Celsius. At ∐0°C = 263 K, not ∐10 K.

⚠️

Pressure must be constant

This law holds only at constant pressure. If pressure changes, use Combined Gas Law.

⚠️

Extrapolation to 0 K

Charles's law predicts V = 0 at 0 K (absolute zero). Real gases liquefy before this.

Frequently Asked Questions

Who discovered Charles's Law? ▾

Jacques Charles in 1787. Published by Joseph Gay-Lussac in 1802, crediting Charles. States V ∝ T at constant P.

Why Kelvin and not Celsius? ▾

At 0°C (273 K), gas still has volume. Charles's law requires V ∝ T, which means V=0 at T=0. Only absolute temperature (Kelvin) has a true zero.

What happens to gas at very low temperatures? ▾

Real gases deviate from Charles's law and eventually liquefy. Nitrogen liquefies at 77 K, oxygen at 90 K.

How is Charles's Law used in hot air balloons? ▾

Heating air from 20°C (293 K) to 100°C (373 K) expands it by 373/293 = 1.27x. Expanded air is less dense than outside air, providing lift.

What is the temperature of absolute zero? ▾

0 K = −273.15°C = −459.67°F. The theoretical temperature at which molecular motion ceases. Unattainable in practice.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship connects pressure, volume, temperature, amount or phase composition for gases and volatile mixtures. Assumption: Use absolute temperature and compatible pressure-volume units. Ideal behavior weakens at high pressure, low temperature, strong intermolecular attraction or near phase change.

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