Chapter 6 Vocab

Question 1

Internal energy (E)

Answer 1

The sum of the kinetic and potential energies of all the particles in a system.

Question 2

Heat (q)

Answer 2

(Also thermal energy) The energy transferred between objects because of a difference in their temperatures only.

Question 3

Work (w)

Answer 3

The energy transferred when an object is moved by a force.

Question 4

State function

Answer 4

A property of a system determine only by the system’s current state, regardless of how it arrived at that state.

Question 5

Pressure-volume work

Answer 5

(Also PV work) A type of mechanical work done when a volume change occurs against an external pressure.

Question 6

Enthalpy (H)

Answer 6

A thermodynamic quantity that is equal to the system’s internal energy plus the product of the pressure and volume.

Question 7

Change in enthalpy (ΔH)

Answer 7

The change in the system’s internal energy plus the product of the constant pressure and the change in volume: ΔH = ΔE + PV; alternatively, the heat lost or gained at constant pressure: ΔH = qp.

Question 8

Exothermic process

Answer 8

A process that occurs with a release of heat to the surrounding and therefore a decrease in the enthalpy of the system (ΔH < 0).

Question 9

Enthalpy diagram

Answer 9

A graphic depiction of the enthalpy change of a system.

Question 10

Endothermic process

Answer 10

A process that occurs with an absorption of heat from the surroundings and therefore an increase in the enthalpy of the system (ΔH > 0).

Question 11

Heat capacity (C)

Answer 11

The quantity of heat required to change the temperature of an object by 1 K.

Question 12

Specific heat capacity (c)

Answer 12

The quantity of heat required to change the temperature of 1 gram of a substance or material by 1 K.

Question 13

Molar heat capacity (Cm)

Answer 13

The quantity of heat required to change the temperature of 1 mol for substance by 1 K.

Question 14

Calorimeter

Answer 14

A device used to measure the heat released or absorbed by a physical or chemical process taking place within it.

Question 15

Thermochemical equation

Answer 15

A balanced chemical equation that includes the enthalpy change for the reaction.

Question 16

Hess’s law

Answer 16

A law stating that the enthalpy change of an overall process is the sum of the enthalpy changes of the individual steps.

Question 17

Standard state

Answer 17

A set of specific conditions used to compare thermodynamic data: 1 atm for gases behaving ideally, 1 M for dissolved species, or the pure substance for liquids and solids.

Question 18

Standard enthalpy of reaction

Answer 18

(Also standard heat of reaction) The enthalpy change that occurs during a reaction when all components are in their standard states.

Question 19

Formation equation

Answer 19

An equation in which 1 mole of a compound forms from its elements.

Question 20

Standard enthalpy of formation

Answer 20

(Also standard heat of formation) The enthalpy change occurring when 1 mol of a compound forms from its elements with all components in their standard states.

Question 21

Fossil fuels

Answer 21

Any fuel, including coal, petroleum, and natural gas, derived from the products of the decay of dead organisms.

Question 22

Coal gasification

Answer 22

An industrial process for altering the large molecules in coal to sulfur-free gaseous fuels.

Question 23

Biomass conversion

Answer 23

The process of applying chemical and biological methods to convert plant or animal matter into fuels.

Question 24

Methanogenesis

Answer 24

The process of producing methane by anaerobic biodegradation of plant and animal waste.

Question 25

Photovoltaic cell

Answer 25

A device capable of converting light directly into electricity.