Charles Law Calculator
Calculate gas volume or temperature at constant pressure using Charles’s law. Enter any three inputs; instantly compute the fourth value.
Equation Preview
Helping Notes
- Charles’s law: \( \dfrac{V_1}{T_1}=\dfrac{V_2}{T_2} \) at constant pressure and fixed amount of gas.
- Enter any three values; the blank one is solved. Converted internally to SI (m³, K) for computation.
- Kelvin must be positive. We convert °C and °F to K: \(K=(°C+273.15)=(°F-32)\cdot5/9+273.15\).
Results
Solved Value
Substitutions
Error
Steps
What is Charles’s Law Calculator?
A Charles’s Law Calculator determines how a gas’s volume changes with temperature when pressure and amount of gas remain constant. Charles’s law states that volume is directly proportional to absolute temperature (Kelvin). If \(V\) is volume and \(T\) is temperature, then \(V/T\) is constant for a fixed pressure and fixed moles of gas. This emerges from the ideal gas law \(PV=nRT\): holding \(P\) and \(n\) fixed yields \(V/T=nR/P=\text{constant}\). Always convert Celsius to Kelvin before computing to ensure proportionality is valid.
About the Charles’s Law Calculator
Enter any two of \(V_1, T_1, V_2, T_2\) and the calculator solves for the unknown, showing algebraic steps and unit handling. It flags common pitfalls—using Celsius instead of Kelvin, negative or zero absolute temperatures, and inconsistent volume units (mL vs L). For teaching, it displays proportionality and rearranged forms, and connects to the combined gas law to emphasize that Charles’s law is the constant‑pressure special case.
How to Use this Charles’s Law Calculator
- Choose the unknown you want to compute (\(V_2\) or \(T_2\)).
- Enter known \(V_1\) and \(T_1\) (convert °C to K via \(T_K=t_{\degree\mathrm{C}}+273.15\)).
- Enter the new temperature \(T_2\) (K) or new volume \(V_2\) (consistent units: L, mL, m³).
- Click calculate to see the rearranged formula, substitution, and final value.
- Review the interpretation: direct proportionality means doubling \(T\) (in K) doubles \(V\) at constant pressure.
Examples
Example 1: Find new volume
\(V_1=2.00\,\text{L}\) at \(t_1=20^{\circ}\text{C}\Rightarrow T_1=293.15\,\text{K}\). Heat to \(t_2=75^{\circ}\text{C}\Rightarrow T_2=348.15\,\text{K}\).
Example 2: Find new temperature
\(V_1=500\,\text{mL}\) at \(t_1=15^{\circ}\text{C}\Rightarrow T_1=288.15\,\text{K}\). When \(V_2=600\,\text{mL}\), find \(t_2\).
Example 3: Connection to ideal gas law
At constant \(P\) and \(n\), \(PV=nRT\) implies \(V/T=nR/P\). If \(P\) changes, use the combined gas law.
FAQs
Do I have to use Kelvin?
Yes. Charles’s law is linear only with absolute temperature; always convert °C to K with \(T_K=t_{\degree\mathrm{C}}+273.15\).
What stays constant in Charles’s law?
Pressure and moles of gas. The law describes \(V\)–\(T\) changes when \(P\) and \(n\) do not change.
Is Charles’s law exact for real gases?
It’s an ideal‑gas approximation; real gases deviate at high pressure or very low temperature.
Can I input Celsius directly?
Enter Celsius if the calculator converts to Kelvin internally; the formulas still operate on Kelvin values.
Does volume unit matter?
Use consistent units across \(V_1\) and \(V_2\) (e.g., both in L). Ratios cancel, but consistency avoids mistakes.
What if pressure changes?
Then Charles’s law no longer applies. Use the combined gas law \(P_1V_1/T_1=P_2V_2/T_2\).
Can the volume become negative?
No. Negative results indicate an input or unit error; volumes are nonnegative physical quantities.
What happens at 0 °C?
It’s simply 273.15 K. The law holds provided the gas remains in a single phase and pressure is constant.