Book: Ch. 5 Flashcards
Define: pressure
Pressure = force / area
Define: barometer
device used to measure atmospheric pressure.
Define: manometer
Device used to measure the pressure of a gas.
Define: pascal (Pa)
The SI unit of pressure: 1 Pa = 1 N/m²
What is average atmospheric pressure at sea level and 0º C in terms of Pa?
1 atm = 101.325 kPa
Define: the unit of pressure millimeter of mercury (mmHg) (aka torr)
1 torr = 1 mmHg = 1/760 atm = 133.322 Pa
also: 1 atm = 760 mmHg = 760 torr
Define: ideal gas
A gas that exhibits linear relationships among volume, pressure, temperature, and amount.
Define: Boyle’s law
PV = constant [T and n fixed]
Define: Charles’s law
V/T = constant [P and n fixed]
Define: Avogadro’s law
V/n = constant [P and T fixed]
Define: standard temperature and pressure (STP)
STP: 0º C (273.15 K) and 1 atm (760 torr)
Define: standard molar volume
Standard molar volume = 22.4141 L or 22.4 L [to 3 s.f.]. At STP, this is the volume of 1 mol of an ideal gas.
Define: ideal gas law
PV = nRT
Define: universal gas constant
R = PV/nT = 0.082058 (atm L)/(mol K)
What is the equation for the density of a gas in terms of P, M, R, and T?
m/V = d = PM/RT, with M being the molar mass of the gas.
What is the equation for the molar mass of a gas in terms of m, R, T, P, and V?
M = mRT/PV since n = m/M = PV/RT
Define: Dalton’s law of partial pressures
The total pressure is the sum of the partial pressures: P total = ∑ P partial
Define: mole fraction
Each component of a mixture contributes a fraction of the total number of moles in the mixture; this portion is the mole fraction (X) of the component: P_A = X_A P_total
Define: kinetic-molecular theory
A model that accounts for macroscopic gas behavior at the level of individual particles (atoms or molecules).
Define: rms speed (u_rms)
Speed of a gas particle that has the average kinetic energy of the particles in the sample: u_rms = sqrt(3RT/M)
Define: effusion
The process by which a gas escapes through a tiny hole in its container.
Define: Graham’s law of effusion
rate A / rate B = sqrt(M_B / M_A)
Define: diffusion
Movement of one gas through another
What is the equation for the rate of diffusion?
rate A / rate B = sqrt(M_B / M_A)
Define: mean free path
The average distance a particle travels between collisions at a given temperature and pressure in a gas.
Define: collision frequency
Average number of collisions per second that each particle in a gas undergoes.
Define: van der Waals equation
An equation to account for the behavior of real gases. For n moles of a real gas, it is (P + n²a/V²)(V - nb) = nRT, where a and b are van der Waals constants. a and b are experimentally determined and specific for a given gas.
