Combined Gas Law (final pressure)

The Combined Gas Law (Final Pressure) computes the final pressure based on the initial and final temperatures and volumes and the initial pressure.

INSTRUCTIONS: Choose units and enter the following:

• (P_i) Initial Pressure
• (T_i) Initial Temperature
• (T_f) Final Temperature
• (V_i) Initial Volume
• (V_f) Final Volume

Final Pressure (P_f): The calculator return the final pressure in pascals. However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The Combined Gas Law  associates the pressure, volume, temperature and a constant of a gas, based on a combination of Charles's law, Boyle's law, and Gay-Lussac's law. There is no 'official' founder for this law because it is a consolidation of the three other laws.  The combined gas law states the ratio between the pressure-volume product and the temperature of a system remains constant (k).  This constancy can be used when comparing different conditions using the same substances. The combined gas law is mathematically expressed as follows:

`(P_i V_i)/(T_i) = (P_(f) V_f)/(T_f) = k`

The Combined Gas Law calculator groups the forms of the Combined Gas Law formula in two ways as follows:

P • V / T = k 

• Pressure based on known volume, temperature and the combined gas constant.
• Volume based on know pressure, temperature and the combined gas constant.
• Temperature based on known pressure, volume and the combined gas constant.
• k gas constant based on the proportionality of the gas if you know pressure, volume and the temperature for the specific gas.

P_i • V_i/T_i = P_f • V_f/T_f

Since P•V/T = k, one can compute the initial (i) and final (f) states using the expanded version of the Combined Gas Law. The P_i • V_i/T_i = P_f • V_f/T_f tab allows the user to enter any five of the six values in the formula to compute the remaining one via the Combined Gas Law.

• Final Pressure based on an initial and final temperature and volume and an initial pressure.
• Final Temperature based on an initial and final pressure and volume and an initial temperature.
• Final Volume based on an initial and final pressure and temperature and an initial volume.

Related Calculators

• Boyle's Law Calculator:  P₁ • V₁ = P₂ • V₂
• Charles Law Calculator: V₁• T₂ = V₂ • T₁
• Combined Gas Law Calculator:   P•V / T= k
• Gay-Lussac Law:  T₁•P₂ =T₂•P₁ 
• Ideal Gas Law: P•V = n•R•T