Book: Ch. 5

Question 1

Define: pressure

Answer 1

Pressure = force / area

Question 2

Define: barometer

Answer 2

device used to measure atmospheric pressure.

Question 3

Define: manometer

Answer 3

Device used to measure the pressure of a gas.

Question 4

Define: pascal (Pa)

Answer 4

The SI unit of pressure: 1 Pa = 1 N/m²

Question 5

What is average atmospheric pressure at sea level and 0º C in terms of Pa?

Answer 5

1 atm = 101.325 kPa

Question 6

Define: the unit of pressure millimeter of mercury (mmHg) (aka torr)

Answer 6

1 torr = 1 mmHg = 1/760 atm = 133.322 Pa

also: 1 atm = 760 mmHg = 760 torr

Question 7

Define: ideal gas

Answer 7

A gas that exhibits linear relationships among volume, pressure, temperature, and amount.

Question 8

Define: Boyle’s law

Answer 8

PV = constant [T and n fixed]

Question 9

Define: Charles’s law

Answer 9

V/T = constant [P and n fixed]

Question 10

Define: Avogadro’s law

Answer 10

V/n = constant [P and T fixed]

Question 11

Define: standard temperature and pressure (STP)

Answer 11

STP: 0º C (273.15 K) and 1 atm (760 torr)

Question 12

Define: standard molar volume

Answer 12

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.

Question 13

Define: ideal gas law

Answer 13

PV = nRT

Question 14

Define: universal gas constant

Answer 14

R = PV/nT = 0.082058 (atm L)/(mol K)

Question 15

What is the equation for the density of a gas in terms of P, M, R, and T?

Answer 15

m/V = d = PM/RT, with M being the molar mass of the gas.

Question 16

What is the equation for the molar mass of a gas in terms of m, R, T, P, and V?

Answer 16

M = mRT/PV since n = m/M = PV/RT

Question 17

Define: Dalton’s law of partial pressures

Answer 17

The total pressure is the sum of the partial pressures: P total = ∑ P partial

Question 18

Define: mole fraction

Answer 18

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

Question 19

Define: kinetic-molecular theory

Answer 19

A model that accounts for macroscopic gas behavior at the level of individual particles (atoms or molecules).

Question 20

Define: rms speed (u_rms)

Answer 20

Speed of a gas particle that has the average kinetic energy of the particles in the sample: u_rms = sqrt(3RT/M)

Question 21

Define: effusion

Answer 21

The process by which a gas escapes through a tiny hole in its container.

Question 22

Define: Graham’s law of effusion

Answer 22

rate A / rate B = sqrt(M_B / M_A)

Question 23

Define: diffusion

Answer 23

Movement of one gas through another

Question 24

What is the equation for the rate of diffusion?

Answer 24

rate A / rate B = sqrt(M_B / M_A)

Question 25

Define: mean free path

Answer 25

The average distance a particle travels between collisions at a given temperature and pressure in a gas.

Question 26

Define: collision frequency

Answer 26

Average number of collisions per second that each particle in a gas undergoes.

Question 27

Define: van der Waals equation

Answer 27

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.