Ideal Gas Law (PV = nRT)
The Ideal Gas Law relates the pressure (P), volume (V), temperature (T), and amount of substance (n) of an ideal gas through the equationPV = nRT, whereR is the universal gas constant (8.314462618 J/(mol·K)). This calculator helps you compute one property when the other three are known or check consistency between your provided values. Understanding the Ideal Gas Law is essential for many scientific and engineering fields, making this calculator an invaluable tool for students, professionals, and hobbyists.
How to Use the Ideal Gas Law Calculator
- Enter values for pressure (P in pascals), volume (V in m³), number of moles (n in mol), and temperature (T in K).
- Choose the compute mode: Auto will compute a single missing value or check consistency when all four are provided. You can also explicitly choose which variable to compute.
- Results update automatically as you change inputs — no calculate button required.
- Download a PDF of the inputs and results using the download button.
Examples of Using the Ideal Gas Law
Example 1: Compute Pressure
Given n = 2 mol, T = 300 K, V = 0.05 m³ → P = nRT / V = (2 × 8.314462618 × 300) / 0.05 ≈ 99,773 Pa
Example 2: Compute Moles
Given P = 101325 Pa, V = 0.0224 m³, T = 273 K → n = PV / (RT) ≈ 1 mol
Frequently Asked Questions about the Ideal Gas Law
Is the Ideal Gas Law always accurate?
The Ideal Gas Law is an approximation that works well for many gases at moderate temperatures and low pressures. Real gases can deviate from ideal behavior at high pressures and low temperatures due to intermolecular forces and the finite volume of molecules.
What units should I use?
Use SI units: pressure in pascals (Pa), volume in cubic meters (m³), temperature in kelvin (K), and amount in moles (mol). The calculator assumes these units for correct results.
Why does the calculator sometimes show a difference between provided and calculated pressure?
When all four properties are provided, the calculator computes the pressure from n, R, T, and V and compares it against the provided pressure. Small differences can arise from rounding or measurement error. Large disagreements indicate inconsistent inputs or non-ideal gas behavior.
Can the Ideal Gas Law be applied to real gases?
While the Ideal Gas Law offers great easy calculations for many scenarios, it does not perfectly describe real gases. When accuracy is critical, especially under high pressure or low temperature, use more complex equations of state.
Notes on the Ideal Gas Law Calculator
R used in this calculator: 8.31446261815324 J/(mol·K). If you require more advanced corrections (like van der Waals forces, compressibility factors), consider using an equation of state appropriate for real gases.