Chapter 7

Question 1

Thermochemistry

Answer 1

study of the relationships between chemistry and energy

Question 2

Energy

Answer 2

capacity to work

Question 3

Work

Answer 3

the result of a force acting through a distance

Question 4

heat

Answer 4

the flow of energy by a temperature difference

Question 5

kinetic energy

Answer 5

energy associated with the motion of an object

Question 6

Thermal energy

Answer 6

energy associated with the temperature of an object

Question 7

potential energy

Answer 7

energy associated with the position or composition of an object

Question 8

chemical energy

Answer 8

energy is associated with the relative positions of electrons and nuclei in atoms and molecules

Question 9

law of conservation of energy

Answer 9

energy can be neither created nor destroyed

Question 10

surrounding

Answer 10

everything with which the system can exchange energy

Question 11

kinetic energy

Answer 11

1/2 mv^2
m- kg
v- m/s
kinetic energy - J

Question 12

1 calories (cal) to Joules (J)

Answer 12

1 cal = 4.184 J

Question 13

kilo watt per hour to joules

Answer 13

1 kWh = 3.60 x 10^6 J

Question 14

thermodynamics

Answer 14

the general study of energy and its interconversions

Question 15

first law of thermodynamics

Answer 15

the total energy of the universe is constant

Question 16

internal energy (E)

Answer 16

the sum of the kinetic and potential energies of all of the particles that compose the system

Question 17

The internal energy of a chemical system

Answer 17

delta E = E(products) - E(reactants)

Question 18

Reactants have a higher internal energy than the products

Answer 18

delta E(sys) Is negative
-energy flows out of the system into the surroundings

Question 19

reactants have a lower internal energy than the products

Answer 19

delta E(sys) is postive
energy flows into the system from the surroundings

Question 20

Change in thermal energy of the system

Answer 20

heat transfer (q) + work done (w)

Question 21

when q is positive

Answer 21

system gains thermal energy

Question 22

when q is negative

Answer 22

system loses thermal energy

Question 23

when w is positive

Answer 23

work down on the system

Question 24

when w is negative

Answer 24

work done by the system

Question 25

when a change in internal energy is positive

Answer 25

energy flows into the system

Question 26

when a change in internal energy is negative

Answer 26

energy flows out of the system

Question 27

Delta E(sys)

Answer 27

• delta E (surr)

Question 28

higher the heat capacity of a system

Answer 28

smaller the change in temperature for a given amount of absorbed heat

Question 29

The formula for F, W, D

Answer 29

Work = work as a force (F) x acting through a distance (D)

Question 30

the formula for F, P, A

Answer 30

Force = external pressure (P ext) x Area the pressure acts on (A)

Question 31

The formula for W, P, V

Answer 31

Work = -Pext x change in volume

Question 32

Enthalpy (H)

Answer 32

a system as the sum of its internal energy and the product of its pressure and volume

Question 33

Formula for enthalpy

Answer 33

H = change in E + P (change in V)

Question 34

Endothermic reaction

Answer 34

chemical reaction with a positive H
- absorbs heat from its surroundings
- strong bonds break to form weak bonds

Question 35

Exothermic reaction

Answer 35

chemcial reaction with a negative H
- weak bonds break to form strong bonds

Question 36

standard delta H(rxn)

Answer 36

sum of (delta Hf products x stoichiometry) - sum of (delta Hf reactants x stoichiometry)