Charles's Law — Science definition
At constant pressure, the volume of a fixed amount of gas is directly proportional to its Kelvin temperature: V₁/T₁ = V₂/T₂.
Where it is taught
- The Gas Laws — States of Matter & Gases, Physical Science: Chemistry, Grade 11
In use
Charles's Law freezes the pressure instead and links volume to temperature, and here the two rise together — they are directly proportional.
The Gas Laws
Questions using charles's law
Problem 1
A student uses 25°C directly in Charles's Law and gets the wrong answer. What did they do wrong, and what should they have used?
Answer and explanation
They forgot to convert to kelvin. Charles's Law requires absolute temperature, so 25°C must first become 25 + 273 = 298 K. Using the Celsius value gives an incorrect ratio because the Celsius scale does not start at absolute zero.