Chapter 5: Thermochemistry

Question 1

thermodynamics

Answer 1

studies of energy changes during physical and chemical changes

Question 2

thermochemistry

Answer 2

deals with energy changes during the chemical reactions

Question 3

energy

Answer 3

capacity to do work or transfer heat

Question 4

heat

Answer 4

the energy transferred from a hotter object to a cooler one

Question 5

units of energy

Answer 5

Joule, J = kg*m^2/s^2

1 cal = 4.184 J

Question 6

calorie

Answer 6

the amount of heat energy needed to warm up 1.00 g of pure liquid water by 1C from 14.5 to 15.5

Question 7

potential energy

Answer 7

energy of position

Question 8

chemical potential energy

Answer 8

reflects relative position of atoms in molecules

Question 9

electrostatic potential energy

Answer 9

reflects interactions between oppositely charged ions and same sign ions at small distances apart

Question 10

kinetic energy

Answer 10

energy of motion; thermal energy of atoms, moecules or ions in motion

Question 11

1st law of thermodynamics

Answer 11

law of conservation of energy = the total energy of the universe is constant (neither created nor detroyed)

Question 12

system

Answer 12

chemical or physical phenomenon that is taking place

Question 13

how does heat travel

Answer 13

always from a hotter to cooler object and only until thermal =m is reached (both objects have the same temperature)

Question 14

the amount of heat lost by the hotter object=

Answer 14

the amount of heat gained by the cooler object

Question 15

exothermic (products < reactants)

Answer 15

heat, q, leaves the system and travels to the surroundings; surroundings feel warmer; -E

Question 16

endothermic (products > reactants)

Answer 16

heat, q, leaves the surroundings and travels to the system; surroundings feel cooler; +E

Question 17

thermoneutral process

Answer 17

there is no heat transfer; energy is still transferred just not in the form of heat

Question 18

system expansion , w<0

Answer 18

exothermic if the system loses heat; endothermic if the system gains heat

Question 19

system shrinks because the surrounding is doing work on the system, w>0

Answer 19

endothermic if the system gains heat; exothermic if the system loses heat

Question 20

state function

Answer 20

a function whose change depends only on the final and initial states not on the path between them

Question 21

what are NOT state functions?

Answer 21

heat and work

Question 22

enthalpy <0

Answer 22

EXOTHERMIC

Question 23

enthalpy > 0

Answer 23

ENDOTHERMIC

Question 24

enthalpy

Answer 24

the heat energy that takes place during chemical reactions

Question 25

small specific heat

Answer 25

means it does not take much to warm it up

Question 26

q>0

Answer 26

heat is ABSORBED

Question 27

q<0

Answer 27

heat is RELEASED

Question 28

calorimetry

Answer 28

measures heat flow by measuring the temperature difference that occur on the surroundings

Question 29

calorimeter

Answer 29

apparatus that measures heat flow

Question 30

Hess’s Law

Answer 30

if a reaction is carried out in a series of steps, deltaH(rxn) for the reaction will equal the sum of the enthalpy changes for the individual steps

Question 31

vaporization

Answer 31

going from a liquid to a gas

Question 32

fusion

Answer 32

melting solids

Question 33

combustion

Answer 33

combusting substance in O2

Question 34

standard enthalpy of formation

Answer 34

heat of a reaction in which 1 mole of a compound is formed from elements at the pressure of 1 atm; all substances must be in there standard state