Module 13 Flashcards Preview

Apologia Chemistry > Module 13 > Flashcards

Flashcards in Module 13 Deck (33)
Loading flashcards...
1

Hess's Law

Enthalpy is a state function and is therefore independent of path.

2

State function

any quantity that depends solely on the final destination, not on the way you get to that destination

3

for enthalpy, the amount of energy contained in a substance is

independent of how it is made

4

enthalpy of formation (ΔHf)

the ΔH of a formation reaction

5

standard conditions

a temp of 25 C and a pressure of 1.00 atm

6

standard enthalpies of formation

the ΔHf for molecules under standard conditions
denoted with an "°"

7

the ΔH° of any chemical reaction is the

sum of the ΔHf° for the products minus the sum of the ΔHf° for the reactants

8

when a reaction is exothermic energy will be thought of a s

a product in the reaction

9

when a reaction is endothermic energy will be thought of as

a reactant in the reaction

10

enthalpy

the energy stored in a substance
stated as the 'enthalpy of that substance'
symbolized by 'H'

11

change in enthalpy (ΔH)

the energy change that accompanies a chemical reaction

12

1 calorie =

4.184 Joules

13

ΔH is positive for -- reactions and negative for -- reactions

endothermic
exothermic

14

whether a reaction is exothermic or endothermic, energy is both-- and-- during the course of the reaction. the difference is ---

absorbed
released
how much

15

bond energy

the strength of a chemical bond

16

ΔH=

energy required to bread bonds/ energy released when bonds form

17

the standard enthalpy of formation of an element in its elemental form is

zero

18

energy diagram

a 'picture' of the energy associated with a chemical reaction

19

reaction coordinate

tells us how close the reaction is to completion
plotted on the horizontal/ x axis of the graph

20

intermediate state/ activated complex

occurs at the top of the hump, which represents the midpoint of the reaction

21

activation energy

the energy necessary to start a chemical reaction

22

entropy

a measure of the disorder that exists in any system
denoted by an 'S'

23

2nd law of thermodynamics

the entropy of the universe must always either increase or remain the same. It can never decrease

24

which state has the least amount of entropy associated with it? How about the middle amount? What about the highest amount?

solid
liquid
gaseous

25

the entropy of a system increases with -- temp

increasing

26

the entropy of a system increases os the matter it contains--

increases

27

ΔS universe ≥

0

28

all substances, even elements have

an absolute entropy

29

what does the Gibbs Free equation tell us?

whether or not a reaction is consistent with the second Law of thermodynamics

30

if a reaction is consistent with the second law, we call it

spontaneous
this is because we know that it con proceed