converting between partial pressure and concentration

Moderators: Chem_Mod, Chem_Admin

Madelyn Cearlock
Posts: 72
Joined: Fri Sep 28, 2018 12:19 am

converting between partial pressure and concentration

Postby Madelyn Cearlock » Sun Jan 13, 2019 4:05 pm

Can someone please explain to me how to convert between partial pressure and concentration?

505095793
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: converting between partial pressure and concentration

Postby 505095793 » Sun Jan 13, 2019 4:20 pm

The main use of the ideal gas law, PV=nRT, for us is to convert between Kc and Kp (concentration and partial pressure). You can think of the ideal gas equation as Kp=Kc(RT)^(n). In this case n=(c+d)-(a+b) according to the reaction form aA+bB=cC+dD.

Luc Lorain 1L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

Re: converting between partial pressure and concentration

Postby Luc Lorain 1L » Sun Jan 13, 2019 6:09 pm

Like the post above states, we do have to use the equation of the ideal gas law, PV=nRT, where P=pressure in atm, V=volume in L, n=moles of substance, R=ideal gas constant, and T=temperature in Kelvin. In order to convert between partial pressure (P) and concentration (M), we need to manipulate this equation to get our desired answer, and must be provided with the value of the temperature at which the rxn takes place.

To convert concentration --> partial pressure, set the ideal gas law to be: P=(n/V)RT. Because concentration (M) = n/V, we can change this to be P=MRT.
Making sure that all units are correct, you should be able to use this equation to find the partial pressure for each individual gas in equilibrium.

To convert partial pressure --> concentration, set the ideal gas law to be : (n/V)= P/RT --> M= P/RT. Use this equation for each species in equilibrium.


Return to “Equilibrium Constants & Calculating Concentrations”

Who is online

Users browsing this forum: No registered users and 1 guest