Chapter 5 Vocab

Question 1

Pressure (P)

Answer 1

The force exerted per unit of surface area.

Question 2

Barometer

Answer 2

A device used to measure atmospheric pressure. Most commonly, a tube open at one end, which is filled with mercury and inverted into a dish of mercury.

Question 3

Manometer

Answer 3

A device used to measure the pressure of a gas in a laboratory experiment.

Question 4

Pascal (Pa)

Answer 4

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

Question 5

Standard atmosphere (atm)

Answer 5

The average atmospheric pressure measured at seal level and 0°C, defined as 1.01325x10^5 Pa.

Question 6

Millimeter of mercury (mmHg)

Answer 6

A unit of pressure based on the difference in the heights of mercury in a barometer or manometer. Renamed the torr in honor of Torricelli.

Question 7

Torr

Answer 7

A unit of pressure identical to 1 mmHg.

Question 8

Ideal gas

Answer 8

A hypothetical gas that exhibits linear relationships among volume, pressure, temperature, and amount (mol) at all conditions; approximated by simple gases at ordinary conditions.

Question 9

Boyle’s law

Answer 9

The gas law stating that, at constant temperature and amount of gas, the volume occupied by a gas is inversely proportional to the applied (external) pressure: V ∝ 1/P.

Question 10

Charles’s law

Answer 10

The gas law stating that, at constant pressure, the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature: V ∝ T.

Question 11

Avogadro’s law

Answer 11

The gas law stating that, at fixed temperature and pressure, equal volumes of any ideal gas contain equal number of particles, and, therefore, the volume of the gas is directly proportional to its amount (mol): V ∝ n.

Question 12

Standard temperature and pressure (STP)

Answer 12

The reference conditions for a gas: 0°C (273.14 K) and 1 atm (760 torr).

Question 13

Standard molar volume

Answer 13

The volume of 1 mol of an ideal gas at standard temperature and pressure: 22.414 L.

Question 14

Ideal gas law

Answer 14

(Also ideal gas equation) An equation that expresses the relationships among volume, pressure, temperature, and amount (mol) of an ideal gas: PV = nRT.

Question 15

Universal gas constant (R)

Answer 15

A proportionality constant that relates the energy, amount of substance, and temperature of a system; R = 0.082057366 atm⋅L/mol⋅K = 8.3144626 J/mol⋅K.

Question 16

Partial pressure

Answer 16

The portion of the total pressure contributed by a gas in a mixture of gases.

Question 17

Mole fraction (X)

Answer 17

A concentration term expressed as the ratio of number of moles of solute to the total number of moles (solute plus solvent).

Question 18

Kinetic-molecular theory

Answer 18

The model that explains macroscopic gas behavior in terms of particles in random motion whose volumes and interactions are negligible.

Question 19

rms (root-mean-square) speed (urms)

Answer 19

The speed of a molecular having the average kinetic energy; very close to the most probable speed.

Question 20

Effusion

Answer 20

The process by which a gas escapes from its container through a tiny hole into an evacuated space.

Question 21

Diffusion

Answer 21

The movement of one fluid through another.

Question 22

Mean free path

Answer 22

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

Question 23

Collision frequency

Answer 23

The average number of collisions per second that a particle undergoes.

Question 24

Atmosphere

Answer 24

The mixture of gasses that extends from a planet’s surface and eventually merges with outer space; the gaseous region of Earth’s crust (for the unit, see standard atmosphere).

Question 25

van der Waals equation

Answer 25

An equation that accounts for the behavior of real gases.

Question 26

van der Waals constants

Answer 26

Experimentally determined positive numbers used in the van der Waals equation to account for the inter particle attractions and particle volume of real gases.