Physical Chemistry - The First Law

Front 1

work

Back 1

done when an object is moved against an opposing force

Front 2

energy

Back 2

the capacity to do work

Front 3

heat

Back 3

energy transfer as a result of a temperature difference between the system and its surroundings

Front 4

diathermic

Back 4

boundary if a change of state is observed when two objects at different temperatures are brought into contact

Front 5

adiabatic

Back 5

boundary in which there is no heat or matter exchange

Front 6

exothermic process

Back 6

releases energy as heat into its surroundings

Front 7

endothermic process

Back 7

energy is acquired from its surroundings as heat

Front 8

thermal motion

Back 8

disorderly movement of molecules as a result of a transfer of energy

Front 9

expansion work

Back 9

motion arising from a change in volume

Front 10

non-expansion work

Back 10

additional motion

Front 11

additional work

Back 11

non-expansion motion

Front 12

free expansion

Back 12

movement against zero opposing force

Front 13

indicator diagram

Back 13

a p,V-graph used to illustrate expansion work

Front 14

reversible change

Back 14

alteration that can be turned around by an infinitesimal modification of a variable

Front 15

calorimetry

Back 15

the study of heat transfer during physical and chemical processes

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calorimeter

Back 16

a device for measuring energy transferred as heat

Front 17

adiabatic bomb calorimeter

Back 17

most common device for measuring energy transferred as heat

Front 18

calorimeter constant

Back 18

measured electrically by passing a steady current from a source of known potential difference through a heater for a known period of time; used for calibration purposes; can also be determined by burning a known mass of substance that has a known heat output

Front 19

heat capacity

Back 19

the slope to the tangent of the curve of internal energy vs. temperature

Front 20

heat capacity at constant volume

Back 20

(dU / dT)V

Front 21

molar heat capacity at constant volume

Back 21

intensive property; transfer of energy due to temperature difference per mole of substance

Front 22

specific heat capacity

Back 22

ability to transfer energy due to temperature difference divided by mass

Front 23

internal energy

Back 23

total capacity of a system to do work

Front 24

state function

Back 24

in which the value depends only on the current condition of the system and is independent of how that condition has been prepared

Front 25

First Law of thermodynamics

Back 25

The internal energy of an isolated system is constant.

Front 26

enthalpy

Back 26

H = U + pV; a measure of the total energy of a thermodynamic system

Front 27

isobaric calorimeter

Back 27

a measuring device for studying processes at constant pressure

Front 28

adiabatic flame calorimeter

Back 28

used to measure the change in temperature when a given amount of substance burns in a supply of oxygen

Front 29

differential scanning calorimeter

Back 29

thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature; most sophisticated way to measure enthalpy changes

Front 30

heat capacity at constant pressure

Back 30

the slope of the tangent to a plot of enthalpy against temperature at a steady force per unit area

Front 31

molar heat capacity at constant pressure

Back 31

transfer of energy due to temperature difference per mole of material at a steady force per unit area

Front 32

adiabat

Back 32

the curves of pressure versus volume for changes in which there is no heat or matter exchange

Front 33

thermochemistry

Back 33

the study of the energy transferred as heat during the course of a reaction