Question

What is the final pressure when two gases at different pressure are mixed?

Answer 1

3 answers · Chemistry 

 Best Answer

The easiest way to work this out is from the Ideal Gas Law, PV=nRT. Assuming that they start at the same temperature, this is even easier because both R and T will be constants. 

Lets make the first gas 1, the second gas 2 and the final mix f so that : 

Pressure Gas 1 =P1, Volume Gas 1 = V1, Temperature Gas 1 = T1 
Pressure Gas 2 =P2, Volume Gas 2 = V2, Temperature Gas 2 = T2 
Pressure final mix =Pf, Volume final mix = Vf, Temperature final mix = Tf 

then : P1V1/RT1+P2V2/RT2=PfVf/RTf 

take out the constant R 

P1V1/T1+P2V2/T2=PfVf/Tf 

If T is different for each mix 

Pf=(Tf*(P1V1/T1+P2V2/T2))/Vf 

if T is constant (which I assume from your question) 

P1V1+P2V2=PfVf 

Pf=(P1V1+P2V2)/Vf 

Hope this will help u... :-)