Definition of conditions STP, N, Rbar

[c2sco]

Now I realise thast volume conversions is a topic discussed at great length in other threads here, but none seem to bump into all of this question. I realise that there are various definitions of "standard" gas conditions around in different industries, especially in the USA (and I suspect that most people reading this might be in the USA..)
BUT
Has anyone got a firm view on the differences between
STP (I believe this is 0°C, 101.325 kPa)
N (Normal, as in Nm3/hr)
Rbar (as in Rbar m3/hr) (I suspect this is 20°C, 101.325kPa)
Thanks,
Stuart

 

[c2sco]

Further, I think N is 0°C, 1 barabs (10^5Pa)
Stuart

 

[25362]

Visit

thread124-95060
thread135-97506
thread378-90884
thread378-97454
thread798-106556

 

[c2sco]

Thanks, I'd seen these - nothing there on Rbar conditions unless I've missed it.
S

 

[25362]

As far as I know Rbar is 8.314 J/(mol.k).
Thus, following the ideal gas law and assuming STP conditions taken as T=273.15 K, and P=101.325 bar for 1 mol:

V = nRT/P = (1.0 mol)[8.314 J/(mol.K)](273.15 K)/101325 Pa = 0.02241 m³ = 22.41 L.

Remember J/Pa = (N.m)/(N/m²) = m³.

The standard conditions you mentioned are those of the Compressed Gas Institute, namely 20^oC (=68^oF), and 1 atm=101325 Pa. For these conditions the ideal gas molar volume would be 24 L.

The ideal gas molar volume subject was raised in thread378-97454, in particular when considering the latest IUPAC STP conditions. Whatever the selected definition one should follow Mr Montemayor's advice and explicitly detail these conditions to avoid confusion.

 

[Montemayor]

Stuart:

You may have read the previous countless threads on this subject, but you failed to understand the messages:

There are no universal, standard, normal, or cosmic conditions for gas volumes - except those that various peoples, organizations, or countries want to impose, recommend, or institute because they like their choice or zealously believe in it. In other words, you can name your own so-called standards if you want to; everyone else seems to have done it.

I would advise you to eliminate the obvious headaches and memory cells required to deal with this subject and simply concentrate on always working with designated and fully identified conditions of temperature and pressure - whatever the name they may be assigned. Don't follow the herd over the cliff; be your own engineer and secure in the fact that you know what you are doing.

Art Montemayor
Spring, TX