Chapter 10 Flashcards
What are the 6 characteristics of gases?
nonmetals | simple molecular formulas | low masses | expand spontaneously to fill the volume of a container | highly compressible | form homogenous mixtures
What allows for the existence of the characteristics that gases have?
because the gas molecules are far apart
What are vapors?
substances that exists as solids and liquids under ordinary conditions and can exist in the gaseous state
What is pressure?
the force gas molecules exert on the walls of the container (outward push against walls)
What is the equation for pressure?
P = Force / Area of container
What is atmospheric pressure?
force atmosphere exerts on a given surface area
What is the equation for force?
F = ma
What is the value of acceleration?
9.8 m/s^2
Who is Blaise Pascal?
French scientist who studied pressure
What is the unit of 1 Pascal (Pa)?
N/m^2
How many Pascals is 1 bar?
10^5 Pa
What is a barometer?
a 760 mm long tube filled with mercury = the height of Hg is a measure of atmospheric pressure and changes as the atmospheric pressure changes
Who invented the barometer?
Evangelista Torricelli
What is standard atmospheric pressure?
corresponds to the typical pressure at sea level
What is the unit for atmospheric pressure?
1 atm
How many mmHg = torr = Pa = kPa = bar is 1 atm?
1 atm = 760 mmHg = 760 torr = 1.01325*10^5 Pa = 101.325 kPa = 1.01325 bar
What are the 4 variables needed to define the state of a gas?
temperature (T) | pressure (P) | volume (V) | amount of gas in moles (n)
What does Boyle’s Volume-Pressure relationship state?
volume (V) inversely proportional to pressure (P) @ constant T and n
What does Jacques Charles’ Volume-Temperature relationship state?
volume(V) directly proportional to temperature(T)
who is William Thomson?
aka: Lord Kelvin = Kelvin scale
What was Guy-Lussac’s law of combining volumes?
pressure(P) and temperature(T) are directly proportional
What does Avogadro’s Law state?
volume(V) of a gas is directly proportional to the number of moles (n) of the gas at constant T and P
What was Avogadro’s hypothesis?
equal volumes of gases at the same temperature contain equal numbers of molecules
What is an ideal gas?
hypothetical gas whose pressure, volume, and temperature relationships are described completely by the ideal-gas equation
What is the ideal gas law?
PV = nRT
What is the gas constant and its value?
R = 0.08206 L.atm/mol.K
What are 2 assumptions made when deriving the ideal-gas equation?
ideal gas molecules don’t interact with one another | combined volume of the molecules is smaller than the container volume
What does STP stand for?
standard temperature and standard pressure
What are the conditions for STP?
P = 1 atm | T = 273 K (0 degC)
What is molar volume?
volume occupied by 1 mol of ideal gas at STP
What is the value of the molar volume?
22.41
What is Dalton’s law of partial pressures?
total pressure of a gas mixture = the sum of the pressures that each would exert alone
What is partial pressure?
pressure exerted by a gas in a gas mixture
What is mole fractions?
dimensionless number | expresses the ratio of the #moles of a gas in a gas mixture to the total #moles of the mixture
What is the kinetic molecular theory of gases?
model that depicts what happens to gas particles when conditions (temp, pressure, or volume) change
Who developed the kinetic molecular theory of gases?
Rudolf Clausius
What are the 5 things that summarize the theory of moving molecules?
random motion | negligible molecular volume | negligible forces | constant average kinetic energy | average kinetic energy proportional to temp(T)
What is random motion?
gases consist of large numbers of particles that are in continuous random motion
What is negligible molecular volume?
combined volume of all gas particles is negligible relative to the container that holds these gases
Why are forces negligible in the theory of moving molecules?
attractive and repulsive forces between particles are negligible
What is constant average kinetic energy?
energy can be transferred between particles during collisions as long as temp(T) is constant
What is the average kinetic energy proportional to temperature?
avg KE of the particles is proportional to the absolute temp = @given T = particles of all gases have the same avg KE
What is most probable speed µ(mp)?
molecular speed measured by the largest total of particles
What is root-mean-squared speed µ(rms)?
speed of a particle whose KE is equal to the avg. (mean) KE of all gas particles
What is average (mean) speed µ(av)?
the average (mean) speed of all particles
What are the 2 applications of the kinetic molecular theory to the Gas Laws?
Boyle’s Law (V and P are inverse) at constant T = constant KE = constant µ(rms) | Guy-Lussac’s Law (T and P are direct) at constant V = increase KE = increase µ(rms)
What is effusion of gas particles?
escape of gas particles through a tiny hole
What is diffusion of gas particles?
spread of gas A throughout gas B or space
What is Graham’s Law of Effusion?
effusion rate of a gas is inversely proportional to the sqrt of its molar masses
Who developed Graham’s Law?
Thomas Graham
What is mean free path?
average distance traveled by a molecule in between collisions
What is a short mean free path?
high pressure = crowded space
What is a long mean free path?
low pressure = empty space
What does van der Waals equation state?
takes into account the attraction of gas particles to each other and the finite volume
