AP Chemistry:: Applications Thermodynamics

What is the relationship between the sign of GIBBS FREE ENERGY (delta G) and whether a reaction is THERMODYNAMICALLY SPONTANEOUS, reviewing this key concept from the earlier Thermodynamics unit?

- **A)** A negative delta G indicates a non-spontaneous reaction, the reverse of the actual relationship between the sign of delta G and spontaneity
- **B)** Delta G's sign depends only on temperature, with no actual relationship to reaction spontaneity
- **C)** A NEGATIVE delta G indicates a SPONTANEOUS reaction (thermodynamically favorable under the given conditions), while a POSITIVE delta G indicates a NON-spontaneous reaction
- **D)** This concept has no actual relationship to predicting whether a reaction is spontaneous under given conditions

What is an OXIDATION-REDUCTION (REDOX) reaction, reviewing this key concept from the earlier Kinetics/Reactions material, and why are redox reactions specifically relevant to this unit's focus on ELECTROCHEMISTRY?

- **A)** Electrochemistry is concerned only with reactions that do NOT involve any electron transfer, contradicting the actual redox foundation of this field
- **B)** This concept has no actual relationship to why redox reactions are foundational to electrochemistry
- **C)** A reaction involving the TRANSFER of electrons between substances; because electrochemistry is fundamentally about HARNESSING or DRIVING electron transfer via an electrical circuit, ALL electrochemical processes are built on redox reactions
- **D)** Redox reactions never actually involve electron transfer, making them irrelevant to electrochemistry

What is a GALVANIC (VOLTAIC) CELL, and what general TYPE of process does it use to GENERATE electrical energy?

- **A)** A galvanic cell uses a NON-spontaneous redox reaction, requiring external electrical energy INPUT rather than generating it (this actually describes an electrolytic cell, not a galvanic cell)
- **B)** An electrochemical cell that uses a SPONTANEOUS redox reaction to GENERATE electrical energy -- the reaction's thermodynamic favorability is HARNESSED to produce usable electric current
- **C)** Galvanic cells always require continuous electrical energy input to function, rather than generating energy on their own
- **D)** This type of cell has no actual relationship to generating electrical energy from a spontaneous redox reaction

What is an ELECTROLYTIC CELL, and how does it FUNDAMENTALLY DIFFER from a GALVANIC cell in terms of reaction spontaneity and energy flow?

- **A)** Electrolytic cells always generate MORE electrical energy than they consume, contradicting the requirement for external energy input
- **B)** An electrolytic cell also uses a spontaneous reaction to generate electrical energy, identical to a galvanic cell, with no meaningful distinction between the two
- **C)** This type of cell has no actual relationship to using external electrical energy to drive a non-spontaneous reaction
- **D)** An electrochemical cell that uses EXTERNALLY SUPPLIED electrical energy to DRIVE a NON-spontaneous redox reaction forward -- the OPPOSITE energy relationship of a galvanic cell, which generates energy from a spontaneous reaction

What is an ELECTRODE, and what are the specific NAMES given to the electrode where OXIDATION occurs versus the electrode where REDUCTION occurs, in ANY electrochemical cell (galvanic or electrolytic)?

- **A)** An electrode is a conductor where a half-reaction occurs; the electrode where OXIDATION occurs is called the ANODE, and the electrode where REDUCTION occurs is called the CATHODE -- this naming convention applies to BOTH galvanic and electrolytic cells
- **B)** This concept has no actual relationship to naming specific electrodes based on which half-reaction occurs there
- **C)** The anode is where reduction occurs, and the cathode is where oxidation occurs (the reverse of the actual, universal naming convention)
- **D)** Electrode naming (anode/cathode) is COMPLETELY REVERSED between galvanic and electrolytic cells, with no consistent naming convention across both cell types

What is a HALF-REACTION, and why is it useful to separate an overall redox reaction into TWO separate half-reactions (an oxidation half-reaction and a reduction half-reaction)?

- **A)** A half-reaction always shows BOTH oxidation and reduction occurring simultaneously in a single combined equation, rather than separating them
- **B)** This concept has no actual relationship to separating an overall redox reaction into distinct oxidation and reduction components
- **C)** A half-reaction shows EITHER the oxidation OR the reduction portion of an overall redox reaction separately, showing explicitly how many electrons are LOST or GAINED -- separating them makes it easier to balance the overall reaction and to understand each electrode's individual role in an electrochemical cell
- **D)** Half-reactions are used exclusively for reactions that do NOT involve any electron transfer, contradicting their actual redox-specific purpose

What is a SALT BRIDGE, as a component of a typical GALVANIC cell setup, and what specific PURPOSE does it serve in maintaining the cell's operation?

- **A)** A salt bridge allows ELECTRONS (rather than ions) to flow directly between the two half-cells, bypassing the external circuit entirely
- **B)** This component has no actual relationship to maintaining electrical neutrality between a galvanic cell's two half-cells
- **C)** A salt bridge serves only a DECORATIVE purpose, with no actual functional role in maintaining a galvanic cell's operation
- **D)** A component (often a tube filled with an inert electrolyte) that allows IONS to flow between the two half-cells, maintaining ELECTRICAL NEUTRALITY in each half-cell as electrons flow through the external circuit -- without it, charge would build up and stop the reaction

What is STANDARD REDUCTION POTENTIAL (E°), and what does a MORE POSITIVE standard reduction potential indicate about a species' TENDENCY to be REDUCED (gain electrons)?

- **A)** E° values are used exclusively to measure a solution's TEMPERATURE, rather than a species' tendency to be reduced
- **B)** A more positive E° indicates a species has a WEAKER tendency to be reduced, the reverse of the actual relationship between E° magnitude and reduction tendency
- **C)** Standard reduction potential has no actual relationship to a species' tendency to gain electrons
- **D)** A measured voltage value indicating a species' tendency to be reduced (gain electrons) under standard conditions; a MORE POSITIVE E° indicates a GREATER tendency to be reduced (a stronger oxidizing agent)