Combined Gas Law 12-3 Fff 09

Combined Gas Law The Best of Boyles, Charles & Gay-Lussac’s Laws

A little review  BOYLE’S

LAW –PRESSURE & VOLUME –AS P↑ THEN V↓ –AT CONSTANT T, n

P 1V1

=

A Little review

CHARLES’

LAW: –TEMPERATURE & VOLUME –AS T↑ THEN V↑ –AT CONSTANT P, n

V1 V2 = T1 T2

A Little review

CHARLES’

LAW: –TEMPERATURE & VOLUME –AS T↑ THEN V↑ –AT CONSTANT P, n

V1 V2 = T1 T2

If

Another step up…

we combine all of the relationships from the 3 laws covered thus far

 (Boyle’s,

Charles’s, and Gay-Lussac’s)

We

can develop a mathematical equation that can solve for a situation where 3 variables change :

PV=k1 V/T=k2 P/T=k3

Combined gas AMOUNT IS law HELD

CONSTANT = k IS USED WHEN YOU HAVE A CHANGE IN VOLUME, PRESSURE, OR TEMPERATURE

P1V1 =k T1

P2V2 =k T2

Combined gas  AMOUNT ISlaw HELD CONSTANT  IS

USED WHEN YOU HAVE A CHANGE IN VOLUME, PRESSURE, OR TEMPERATURE

P1V1 P2V2 = T1 T2 P1V1T2 = P2V2T1

Example problem A GAS WITH A VOLUME OF 4.0L AT STP. WHAT IS ITS VOLUME AT 2.0ATM AND AT 30°C?

P1 ⇒ 1atm V1 ⇒4.0 L T1 ⇒ 273K

P2⇒ 2.0 V2 ⇒ ?atm T2 ⇒ 30°C + = 273

PLUG & CHUG P1V1 P2V2 = T1 T2

2.22L = V2