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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: mistaken on May 08, 2004, 05:00:58 PM

Title: why cant you have a negative gas value?
Post by: mistaken on May 08, 2004, 05:00:58 PM

why cant you have a negative gas value?

Title: Re:gas laws
Post by: Mitch on May 08, 2004, 07:54:08 PM

huh?

Title: Re:gas laws
Post by: gregpawin on May 08, 2004, 08:10:30 PM

Are you talking about pressure?  Negative pressure?

Title: Re:gas laws
Post by: Donaldson Tan on May 09, 2004, 02:32:29 AM

 :boff:

negative gas value? LOL.

Values related to gas are the molar gas constant, no. of moles, pressure, volume, temperature. They are all positive by notation, including pressure.

Pressure is only negative when u comparing it to another pressure acting in the opposite direction. Note that pressure is a vector, since it contains the force component.

Title: Re:gas laws
Post by: billnotgatez on May 09, 2004, 01:26:17 PM

If you are talking PV=nrT Then you are talking absolute values for the variables
Absolute pressure – you can not have less than a vacuum
Absolute Temperature – you can not have less than absolute zero
Absolute volume – you can not have less than zero volume
And for the “n” variable you can not have less than no atoms

When using the Ideal Gas Law always use absolute values
Many people make the mistake of using Celsius rather than Kelvin
0 degrees Celsius equals 273.15 degrees Kelvin

Regards,
Bill

Title: Re:gas laws
Post by: MAchemi on April 30, 2005, 02:31:50 PM

when there is a negative given in a gas laws problem, it means that the energy is leaving, that it belongs on the product side of the balanced equation.  Positive means the reactant side.