Skip to main content
Ch.20 - Electrochemistry
Tro - Chemistry: A Molecular Approach 6th Edition
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Non è quello che usi tu?Cambia libro di testo
Capitolo 20, Problema 66a,b

Calculate E°cell for each balanced redox reaction and determine if the reaction is spontaneous as written. a. O2(g) + 2 H2O(l) + 4 Ag(s) → 4 OH–(aq) + 4 Ag+(aq) b. Br2(l) + 2 I–(aq) → 2 Br–(aq) + I2(s)

Guida verificata passo dopo passo
1
Step 1: Identify the half-reactions. The reduction half-reaction is O2(g) + 2 H2O(l) + 4 e- → 4 OH-(aq). The oxidation half-reaction is 4 Ag(s) → 4 Ag+(aq) + 4 e-.
Step 2: Look up the standard reduction potentials for each half-reaction in a table of standard reduction potentials. The standard reduction potential for the reduction of O2 to OH- is +0.40 V. The standard reduction potential for the oxidation of Ag to Ag+ is +0.80 V.
Step 3: Calculate the standard cell potential (Ec°ell) using the formula Ec°ell = E°cathode - E°anode. In this case, the cathode is the reduction half-reaction and the anode is the oxidation half-reaction.
Step 4: If the calculated Ec°ell is positive, the reaction is spontaneous as written. If it is negative, the reaction is non-spontaneous as written.
Step 5: Remember that standard cell potentials are calculated under standard conditions (1 M concentrations, 1 atm pressure, 25°C). If the conditions are different, the actual cell potential may be different from the standard cell potential.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
5m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Standard Electrode Potential (Ec°ell)

The standard electrode potential, Ec°ell, is a measure of the tendency of a chemical species to be reduced, expressed in volts. It is determined under standard conditions (1 M concentration, 1 atm pressure, and 25°C). The overall cell potential for a redox reaction can be calculated by subtracting the reduction potential of the anode from that of the cathode, indicating whether the reaction can occur spontaneously.
Video consigliato:
Percorso guidato
01:27
Standard Cell Potential

Redox Reactions

Redox reactions involve the transfer of electrons between two species, where one is oxidized (loses electrons) and the other is reduced (gains electrons). In these reactions, the oxidation state of the elements changes, and they can be balanced using half-reactions. Understanding the oxidation states and identifying the oxidizing and reducing agents is crucial for analyzing redox processes.
Video consigliato:
Percorso guidato
03:12
Identifying Redox Reactions

Spontaneity of Reactions

A reaction is considered spontaneous if it occurs without external intervention, which can be determined by the sign of the cell potential (Ec°ell). If Ec°ell is positive, the reaction is spontaneous as written; if negative, it is non-spontaneous. This concept is rooted in thermodynamics, where spontaneous processes tend to increase the overall entropy of the system.
Video consigliato:
Percorso guidato
04:20
Spontaneity of Processes