# GAS LAWS (p. 421 – 433 in text book)

* Unlike Ideal Gas Equation, the "Gas Laws" describe one gas undergoing a change in conditions
The Gas Laws are also different from the Ideal Gas Equation because you do not have to convert any
units except temperature that has to be in Kelvins.

Combined Gas Law:                                 P1 V1 = P2 V2
T1       T2

* All of the other gas laws can be derived from the combined gas law. *

~ Boyle's Law
-  describes relationship between pressure and volume when temperature is constant
-  because temperature is constant, it can be excluded from the equation
-  so, equation for Boyle's Law is ____________________________
-  pressure & volume are __________________ proportional
-  graph of pressure vs. volume would have the general shape of

EXAMPLE:  A sample of gas occupies 15 liters under 2.1 atm of pressure.  What would the volume of the gas be if the pressure were decreased to 1.2 atm?  (Assume that temperature is constant.)

~ Charles' Law
- describes relationship between volume and temperature when pressure is constant
- because pressure is constant, it can be excluded from the equation
- so, equation for Charles' Law is ____________________________
- volume & temperature are ________________ proportional
- graph of volume vs. temperature would have the general shape of

EXAMPLE:  When I purchase a helium balloon at the store (where the temperature is 25 oC) for my friend’s birthday, the clerk fills the balloon to a volume of 20.0 liters.  When I go outside, the balloon shrinks to a volume of 17.9 liters.  What is the temperature outside?

~ Gay-Lussac's Law
- describes relationship between pressure and temperature when volume is constant
- because volume is constant, it can be excluded from the equation
- so, equation for Gay-Lussac's Law is _________________________
- pressure & temperature are _______________ proportional
- graph of pressure vs. temperature would have the
general shape of

EXAMPLE:  An aerosol can has an internal pressure of 2.75 atm at room temperature (25 oC).  What is the pressure in the can if I leave it outside in the sun and the temperature goes up to 35 oC?