units in Pv=nrt

[dentalstudent2021]

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thought they always have to be
P = Atm
V= Liters
T=K ?

but apparently not...Just did a question where P was mmHg and T was in K.

so what's the concept behind this ? is Temp the only one that has to be always K

 

[embrojam]

You need to look at the calculation you're doing, and what the units of the givens are.

R can equal 0.0821 L/atm K or 8.314 J/mol K

Now, you need to understand your conversions - and 760 mmHg = 1atm

 

[DAT Destroyer]

thought they always have to be
P = Atm
V= Liters
T=K ?

but apparently not...Just did a question where P was mmHg and T was in K.

so what's the concept behind this ? is Temp the only one that has to be always K

Yes....the concept is simple. P1V1 = P2V2 does NOT have a CONSTANT , thus there is no need to have the pressure and volume in units of atms or liters. In the Ideal gas law......R is a constant with specific units, thus you must respect it. Hope this helps.

Dr. Romano

 

[BYU4you]

I'm pretty sure they won't try to trick you on units if I remember correctly but definitely worth understanding.

 

[dentalstudent2021]

Yes....the concept is simple. P1V1 = P2V2 does NOT have a CONSTANT , thus there is no need to have the pressure and volume in units of atms or liters. In the Ideal gas law......R is a constant with specific units, thus you must respect it. Hope this helps.

Dr. Romano

Thanks everyone and as always thanks Dr. Romano.