Ley Combinada de los Gases
Resuelve la ley combinada de los gases P₁V₁/T₁ = P₂V₂/T₂. Despeja presión, volumen o temperatura final (usa kelvin).
Fórmula principal
(P1V1)/T1 = (P2V2)/T2
How do you use the combined gas law?
For a fixed amount of gas, P₁V₁/T₁ = P₂V₂/T₂. Convert °C to K (add 273 or 273.15), keep P and V units consistent, then rearrange for the unknown: P₂ = P₁V₁T₂/(T₁V₂), V₂ = P₁V₁T₂/(T₁P₂), or T₂ = P₂V₂T₁/(P₁V₁).
Sobre esta herramienta
La ley combinada de los gases es P₁V₁/T₁ = P₂V₂/T₂. Despeja presión, volumen o temperatura final con temperatura absoluta.
Cómo usar esta calculadora
- Elige la variable que quieres despejar y confirma qué valores ya conoces.
- Introduce los datos en unidades coherentes antes de calcular.
- Comprueba si el resultado es físicamente razonable comparándolo con las entradas.
- Usa el desglose paso a paso para ver cómo se aplicó la fórmula.
Ejemplos resueltos
Example 1: find final pressure
A gas at 100 kPa, 2.0 L, and 300 K is heated to 360 K at 2.0 L (volume fixed). P₂ = (100)(2.0)(360) / ((300)(2.0)) = 120 kPa. Check: T rose by 20%, so P rose by 20%.
Example 2: convert °C first
Initial: 1.0 atm, 5.0 L, 27 °C. Final: 2.0 atm, T₂ = ? at 2.5 L. T₁ = 27 + 273 = 300 K. T₂ = (2.0)(2.5)(300) / ((1.0)(5.0)) = 300 K. Using 27 °C raw in the formula would be wrong.
Example 3: find final volume
P₁ = 200 kPa, V₁ = 3.0 L, T₁ = 250 K → P₂ = 100 kPa, T₂ = 250 K. V₂ = (200)(3.0)(250) / ((250)(100)) = 6.0 L. Halving pressure at fixed T doubles volume (Boyle’s law).
Preguntas frecuentes
What is the combined gas law formula?
P₁V₁/T₁ = P₂V₂/T₂ for a fixed amount of gas. It combines Boyle’s, Charles’s, and Gay-Lussac’s laws into one two-state relation. Temperatures must be absolute (kelvin).
Why must temperature be in kelvin?
Gas laws use absolute temperature. 0 °C is 273 K, not zero. Leaving Celsius in P₁V₁/T₁ = P₂V₂/T₂ breaks the ratio and often produces nonsense answers.
How do I convert °C to K for gas laws?
T(K) = T(°C) + 273 (many school papers) or + 273.15. Convert both T₁ and T₂ before substituting. Never mix °C on one side with K on the other.
When should I use the ideal gas law instead?
Use PV = nRT when moles (or mass via molar mass) change, or when you need an absolute state from P, V, n, and T rather than comparing two states of the same sample.
Do pressure and volume units have to be SI?
They must match across both states. kPa with litres is fine if both sides use the same pair. Mixing atm with kPa, or mL with L, without converting will skew the unknown.