Ch 9 Thermodynamic And Electrochemistry

Question 1

What is the first law of thermodynamics?

Answer 1

Energy cannot be created or destroyed, only transformed.

Question 2

True or False: Enthalpy is a measure of the total energy of a thermodynamic system.

Answer 2

True

Question 3

Fill in the blank: The change in enthalpy (ΔH) for an exothermic reaction is ______.

Answer 3

negative

Question 4

What is the formula for calculating Gibbs free energy (ΔG)?

Answer 4

ΔG = ΔH - TΔS

Question 5

True or False: A spontaneous reaction (proceeds without external addition of energy) has a positive ΔG.

Answer 5

False

Question 6

What does the symbol ΔS represent in thermodynamics?

Answer 6

Change in entropy

Question 7

What is the standard state of a substance?

Answer 7

The most stable form of a substance at 1 atm and 25°C (298 K)

Question 8

True or False: In an endothermic reaction, heat is absorbed from the surroundings.

Answer 8

True

Question 9

Fill in the blank: The standard electrode potential (E°) is measured under ______ conditions.

Answer 9

standard

Question 10

What is the unit of electric charge?

Answer 10

Coulomb (C)

Question 11

True or False: A galvanic cell converts chemical energy into electrical energy.

Answer 11

True

Question 12

What is the difference between an anode and a cathode?

Answer 12

Anode is the electrode where oxidation occurs; cathode is where reduction occurs.

Question 13

Fill in the blank: In a galvanic cell ( don’t require more energy) , the anode is ______, while the cathode is ______.

Answer 13

negative; positive

Question 14

What is the significance of the cell potential (Ecell)?

Answer 14

It indicates the driving force of the electrochemical reaction.

Question 15

What are electrolytes?

Answer 15

Substances that dissociate into ions in solution and conduct electricity.

Question 16

What does the term ‘reduction potential’ refer to?

Answer 16

The tendency of a species to gain electrons.

Question 17

Fill in the blank: The overall cell reaction in a galvanic cell is the sum of the ______ reactions.

Answer 17

half

Question 18

What does Delta S represent in thermodynamics?

Answer 18

Delta S represents the change in entropy.

Question 19

What does Delta H represent in thermodynamics?

Answer 19

Delta H represents the change in enthalpy.

Question 20

What does a negative Delta G indicate?

Answer 20

A negative Delta G indicates that a reaction is thermodynamically favorable.

Question 21

True or False: A positive Delta H always indicates an exothermic reaction.

Answer 21

False

Question 22

In which scenario is Delta S considered favorable?

Answer 22

Delta S is favorable when it is positive, indicating increased disorder.

Question 23

What is the standard unit for Delta H?

Answer 23

The standard unit for Delta H is (kJ/mol).

Question 24

What does it mean for a reaction to be at equilibrium in terms of Delta G?

Answer 24

At equilibrium, Delta G equals zero.

Question 25

True or False: A reaction with a positive Delta G can still occur spontaneously.

Answer 25

False

Question 26

What is the effect of temperature on Delta G?

Answer 26

Temperature can affect Delta G through the term -T * Delta S.

Question 27

What is the relationship between Delta H and Delta S for a spontaneous reaction at low temperatures?

Answer 27

At low temperatures, a spontaneous reaction (thermodynamically favorable) is favored if Delta H is negative and Delta S is negative.

Question 28

Multiple Choice: Which of the following conditions must be met for a reaction to be spontaneous? A) Delta G < 0 B) Delta G > 0 C) Delta G = 0

Answer 28

A) Delta G < 0

Question 29

How does an increase in entropy (Delta S) affect Delta G?

Answer 29

An increase in entropy (positive Delta S) can lead to a more negative Delta G, favoring spontaneity.

Question 30

What is the significance of the Gibbs free energy equation?

Answer 30

The Gibbs free energy equation helps predict the spontaneity of a chemical reaction.

Question 31

True or False: A reaction with a negative Delta H and positive Delta S is always spontaneous.

Answer 31

True

Question 32

What is the formula to calculate Delta S for a reaction?

Answer 32

Delta S = S(products) - S(reactants)

Question 33

What does it mean if Delta S is negative?

Answer 33

A negative Delta S indicates a decrease in entropy, meaning the system becomes less disordered.

Question 34

Multiple Choice: Which process is likely to have a positive Delta S? A) Freezing water B) Vaporizing water C) Condensing steam

Answer 34

B) Vaporizing water

Question 35

What is the effect of high temperatures on reactions with a negative Delta S?

Answer 35

High temperatures can make reactions with a negative Delta S less favorable, potentially leading to a positive Delta G.

Question 36

True or False: Delta G can be used to determine the maximum work obtainable from a thermodynamic process.

Answer 36

True

Question 37

What is the importance of the sign of Delta H in determining reaction favorability?

Answer 37

A negative Delta H indicates that the reaction releases heat, which can favor spontaneity.

Question 38

Fill in the blank: At high temperatures, a reaction with a positive Delta S may still be spontaneous if ___ is sufficiently negative.

Answer 38

Delta H

Question 39

What is the term for the energy required to start a reaction, which is separate from Delta G?

Answer 39

Activation energy

Question 40

When is a reaction considered endothermic?

Answer 40

A reaction is considered endothermic when Delta H is positive.