Questions 32-36 refer to the following. Two half-cells are set up as follows: Half-Cell A: Strip of \(\mathrm{Cu}(s)\) in \(\mathrm{CuNO}_{3}(a q)\) Half-Cell B: Strip of \(\mathrm{Zn}(s)\) in \(\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}\) (aq) When the cells are connected according to the diagram below, the following reaction occurs: GRAPH CAN'T COPY $$2 \mathrm{Cu}^{+}(a q)+\mathrm{Zn}(s) \rightarrow 2 \mathrm{Cu}(s)+\mathrm{Zn}^{2+}(a q) E^{\circ}=+1.28 \mathrm{V}$$ What will happen in the salt bridge as the reaction progresses? (A) The Na' ions will flow to the Cu/Cu' half-cell. (B) The Br' ions will flow to the Cu/Cu' half-cell. (C) Electrons will transfer from the Cu/Cu' half-cell to the Zn/Zn" half cell. (D) Electrons will transfer from the \(\mathrm{Zn} / \mathrm{Zn}^{2+}\) half- cell to the Cu/Cu' half cell.

Step by step solution

01

Understanding the Galvanic cell

In a Galvanic cell, the chemical reaction is a spontaneous redox reaction which drives the flow of electrons from the anode (the electrode where oxidation occurs) to the cathode (the electrode where reduction occurs). In this case, we know from the given reaction equation that Zinc is getting oxidized (it is losing electrons) and Copper ions are getting reduced (they are gaining those electrons). Therefore, Zinc is acting as a anode and Copper as the cathode.

02

Understanding the function of the salt bridge

A salt bridge is a U shaped tube containing a relatively inert electrolyte like KNO3, NaCl etc. The main function of the salt bridge is to maintain electrical neutrality within the internal circuit, without the movement of electrons, which pass through the wire connected between the two half cells.

03

Establishing the direction of ion flow

When the Zinc is oxidized, it leaves its electrons in the anode and enters the solution as \(Zn^{2+}\) ions. This would cause charge imbalance, hence to restore the charge balance, the negatively charged ions from the salt bridge flow towards the zinc solution. Likewise, at the copper cathode, \(Cu^{+}\) ions are accepting electrons and getting reduced to form Cu metal, resulting in a positive charge imbalance in the copper solution. To restore the neutrality in half-cell B, positive ions from the salt bridge move towards it.

04

Identifying the correct option

From our understanding of the Voltaic cell, it's clear that electrons will transfer from Zinc to Copper, via the connecting wire, not within the salt bridge. So options (C) and (D) are incorrect. The question does not mention what exactly is the electrolyte in the salt bridge but given options (A) and (B), it's reasonable to assume that it may contain both Na+ and Br- ions. Since we established that the Na+ ions go to copper solution and Br- ions go to zinc solution, Option (A) is correct.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!