4.  Essential for life  Expand to fill container  Compressible  Readily flow  Form homogeneous mixtures with other gases  Vol of gases itself=smaller portion of total volume at room temp. and pressure  Noble gases=monotomic gases  Diatomic gases  Gases: molecular compounds, nonmetals  Vapors

5.  T- temperature (in K)  V- volume (in L)  n- quantity (in moles)  P- pressure (in atm)

6.  P=F/A  Barometer- contains a column of mercury (Hg) whose height is directly related to the pressure exerted by the atmosphere (mm Hg or torr)  Manometer- used to measure pressure in enclosed gases (usually below atm. Pressure); det’ed from the difference in heights of mercury levels in U-tube

7.  Caused by gravity  Atoms of atm.=tiny masses  override gravitational forces  Magnitude: F= ma  a = 9.8 m/s^2

8.  PRESSURE= 1 atm = 760 mmHg = 760 torr = 1.013E5Pa = 101.3kPa  P gas = P atm + P h

9.  Boyle’s Law - V=contant/P (T, n) ;or P 1 V 1 =P 2 V 2  Charles Law- V= constant x T (P, n); or V 1 /T 1 =V 2 /T 2  Gay-Lussac’s Law- V= constant x n (P, T); or P 1 /T 1 =P 2 /T 2

10.  PV=nRT  P in atm  V in L  n in moles  T in K  R is gas constant = 0.0821 L-atm/mol-K  Combined: PV/T=PV/T

11.  STP:  Pressure = 1 atm  Temperature = 0 degrees Celsius = 273K  Volume of 1 mol = 22.4 L

12.  The total pressure of a mixture of ideal gases is the sum of the individual pressures each ideal gas would exert if it were the only gas in the container  P t =P 1 +P 2 +…+P N  P i =n i RT/V  P t =P gas +P H2O

13.  The ratio of the # of moles of a component in a mixture of the total # of moles present  Xi = #of moles of component i / total # of moles in mixture  P A = ( X A ) ( P T )  Vol % of a gas in a mixture = mole fraction of that gas

14.  KMT- at the same temperature, molecules of all gases have the same average translational kinetic energy  rms speed is the square root of the average of the squared velocities of the gas molecules:  The average speed is the average of the velocities:  Temp increases  speed increases  The rms speed of a gas is inversely related to the molar mass of the gas at a given temp:

15.  Is the flow of gas molecules through a small pinhole or small opening into a vacuum  Graham’s Law of Effusion relates the rates of 2 gases escaping through the same pinhole and their molar masses at constant temperature

16.  Diffusion - A process in which a substance gradually mixes with another  Mean Free Path - the average distance gas molecules travel between collisions

17.  Gas molecules- attracts at short distances  do not collide with walls of container like ideal gas  Cause the experimental gas pressure to be less than the ideal-gas pressure  Vol for gas to move in container < total vol of container  Van der Waals equation: