Ch. 4 Equilibrium and Thermodynamics

Question 1

What is reversibility?

Answer 1

reactants are converted into products at the same time products are converted into reactants

Question 2

IN a chemical reaction, the reaction rate is dependant upon?

Answer 2

reactant concentration.

The more product produced, the higher the decomposition rate

Question 3

What is the rate equation of equilibrium?

Answer 3

Rate(forward) = Rate(reverse)

Question 4

A reaction that is Spontaneous favors which direction?

Answer 4

Forward direction, making product

Question 5

A reaction that is non-spontaneous favors which direction?

Answer 5

The reverse direction, to reactants

Question 6

At equilibrium, what is ΔG

Answer 6

0

Question 7

Keq is used to determine equilibrium constant, which is denoted as

Answer 7

products/reactants (coefficients are raised as powers)

Question 8

When Keq favors the products

Answer 8

it will be a large value

Numerator greater than denominator

Question 9

When Keq favors the reactants

Answer 9

It will be a smaller value

Denomenator larger than numerator

Question 10

Which phases should not be included in the equilibrium expression?

Answer 10

Solids and pure liquids (water)

Question 11

How would you calculate Keq for a reverse reaction?

Answer 11

this is the reciprocal of Keq, so 1/Keq

Question 12

What are the units for Keq

Answer 12

moles/liter (Molarity)

Question 13

Keq is negative when reactants are favored (T/F)

Answer 13

False.

Keq should never be negative

Question 14

What is the reaction quotient?

Answer 14

A formula used to determine if a reaction is at equilibrium

It is also used to predict the direction in which the reaction will take to reach equilibrium

Question 15

When Q < Keq

Answer 15

Ratio of products to reactants is lower than at equilibrium, products will want to form.

Question 16

When Q >Keq

Answer 16

Raio of products to reactants is higher than t equilibrium, reactants will want to form.

Question 17

When Q = Keq = 1

Answer 17

Equilibrium is reached

Question 18

Calorimetry mimics which type of reaction?

Answer 18

combustion

Question 19

1 calorie = how many Joules?

Answer 19

4.184

Question 20

What is a calorie?

Answer 20

The amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celcius (1cal/g°C)

Question 21

What is the specific heat capacity of water in Joules and calories

Answer 21

4.184 J/g °C

1 cal/g °C

Question 22

1 mL of water = how many grams?

Answer 22

1 gram

Question 23

What is heat capacity?

Answer 23

The heat required to raise the temperature of a system by 1 °C

Question 24

What is ΔH?

Answer 24

Enthalpy change (unit is kJ/mol)

Question 25

What is Enthalpy?

Answer 25

Heat absorbed/released by the system (heat transfer)

Question 26

Under what conditions would ΔH be negative?

Answer 26

Energy is released Energy is produced Heat is released Heat is produced

Question 27

Under what conditions would ΔH be positive?

Answer 27

Energy is absorbed | Heat is absorbed

Question 28

Enthalpy(H) may also be used with the internal energy of a system. What is the formula?

Answer 28

``` ΔU = Q-W (or ΔU= Q+PΔV) Q= heat transfer W = work done by the system (PV) ```

Question 29

What is an endothermic process?

Answer 29

One that requires heat to work (ΔH positive)

Question 30

What does it mean if something has low entropy?

Answer 30

It has concentrated energy

Question 31

What does it mean if something has High entropy?

Answer 31

energy is spread out among the molecule

Question 32

Which entropy would be a favorable process?

Answer 32

Spontaneous, when ΔS is positive

Question 33

What unit is used for Entropy(S)?

Answer 33

J/K or J/K mol

Question 34

What is the formula for standard entropy(ΔS°)?

Answer 34

Products - reactants

Question 35

The Gibbs free energy formula is

Answer 35

ΔG = ΔH - TΔS

Question 36

What is Gibbs free energy?

Answer 36

The maximum amount of work that can be performed by a system consisting of one or more reversible reactions. This allows us to know if a reaction is spontaneous

Question 37

What type of reaction is ΔH > 0?

Answer 37

Endothermic, heat needs to be added to the system

Question 38

What type of reaction is ΔH < 0?

Answer 38

Exothermic, heat is removed from the system

Question 39

What is ΔHf

Answer 39

Standard Enthalpy of formation (standard heat of formation), the enthalpy change associated with forming one mole of a compound from its elements under standard conditions (1 atm, 25°C)

Question 40

Enthalpy of any element in its elemental form is

Answer 40

0

Question 41

What is the formula for Bond dissociation?

Answer 41

ΔHrxn = ΔH°bonds broken - ΔH°bonds formed

Question 42

Forming bonds is what type of reaction

Answer 42

Exothermic, bonded atoms are more stable and lower in energy

Question 43

If ΔHrxn > 0 it is

Answer 43

Endothermic, energy is required

Question 44

For a reaction to take place it must overcome

Answer 44

Activation energy

Question 45

If ΔG < 0 during a reaction

Answer 45

it is spontaneous and exergonic

Question 46

If products are higher than reactants, energy must be absorbed to form products, how does this relate to ΔG?

Answer 46

non-spontaneous, ΔG is a positive and endergonic reaction

Question 47

What is the difference between Kinetic energy and Thermodynamics?

Answer 47

Kinetics focuses on the rate | Thermodynamics is about stability, spontaneity, and equilibrium

Question 48

Keq and ΔG have a _________ relationship

Answer 48

inverse