   Question Answers

# The standard reduction potential of Zn and Ag in water at 298 K are, Zn$^{2+}$ + 2e$^{-}$ $\rightleftharpoons$ Zn; E$\circ$ = -0.76 V and Ag$^{+}$ + e$^{-}$ $\rightleftharpoons$ Ag;E$\circ$= +0.80 V. Which of the following reactions take place? a- Zn$^{+2}$(aq) +2Ag(s) $\rightarrow$ 2Ag$^{+}$ (aq) + Zn(s)b- Zn (s) +2Ag$^{+}$ (aq) $\rightarrow$ Zn$^{2+}$ (aq) + 2Ag(s)c- Zn$^{+2}$(aq) +Ag$^{+}$(aq) $\rightarrow$ Zn(s) + Ag(s)d- Zn (s) + Ag(s) $\rightarrow$ Zn$^{2+}$ (aq) + Ag$^{+}$(aq)  Hint: We are given with the standard reduction potential of both the metals, i.e Zn, and Ag. Identify the reactions occurring at anode, and at the cathode on the basis of reduction potential. Then, the reaction could be known.

First, let us know about the standard reduction potential. It is considered to be the reduction potential of metals, or ions under the specific conditions. It is the difference between the potential difference of the reactions occurring at the anode, and cathode.
As we know, the specific conditions for standard reduction potential are 298K, 1atm, and 1M solutions.
Now, we can see in the question that the reduction potential of Ag is more than the Zn.
Thus, silver will try to reduce; it means the reaction of zinc will occur at the anode, and it will oxidise (lose electrons).
The reaction of zinc at anode is Zn $\rightarrow$ Zn$^{2+}$ + 2e$^{-}$
Now, the reaction of silver at cathode is Ag$^{+}$ + e$^{-}$ $\rightarrow$ Ag(s), But the silver will gain two electrons, then the reaction will be 2Ag$^{+}$ + 2e$^{-}$ $\rightarrow$ 2Ag(s)
Now, to get the cell reaction we will combine the reaction occurring at anode, and cathode.
Then, the cell reaction is Zn (s) +2Ag$^{+}$ (aq) $\rightarrow$ Zn$^{2+}$ (aq) + 2Ag(s).
Hence, the correct option is (B).

Note: Don’t get confused between the words oxidising and reducing. Just remember that the molecule losing electrons will oxidise, and gain of electrons by the molecule means it will reduce. The above mentioned reactions will help to understand this concept.
View Notes
Preparation of Standard Solution of Oxalic Acid  Reduction Formula  Standard Deviation Formulas  CBSE Class 12 Physics Electrostatic Potential and Capacitance Formula  Potential Energy of Charges in an Electric Field  NSEC 2020- National Standard Examination in Chemistry (NSEC)  Standard Error Formula  Meiosis I - Reductional Cell Division  Electric Potential - Point Charge  NSEB 2020 - National Standard Examination in Biology (NSEB)  Important Questions for CBSE Class 12 Physics Chapter 2 - Electrostatic Potential and Capacitance  NCERT Books Free Download for Class 12 Physics Chapter 2 - Electrostatic Potential and Capacitance  Important Questions for CBSE Class 12 Chemistry Chapter 6 - General Principles and Processes of Isolation of Elements  NCERT Books Free Download for Class 12 Chemistry Chapter 6 - General Principles and Processes of Isolation of Elements  Important Questions for CBSE Class 12 Chemistry Chapter 16 - Chemistry in Everyday life  NCERT Books Free Download for Class 12 Chemistry Chapter 16 - Chemistry in Everyday life  Important Questions for CBSE Class 12 Chemistry Chapter 8 - The d and f Block Elements  NCERT Books Free Download for Class 11 Chemistry Chapter 3 - Classification of Elements and Periodicity in Properties  Important Questions for CBSE Class 11 Chemistry Chapter 3 - Classification of Elements and Periodicity in Properties  NCERT Books Free Download for Class 12 Chemistry Chapter 8 - The d and f Block Elements  Chemistry Question Paper for CBSE Class 12  CBSE Class 12 Chemistry Question Paper 2020  Chemistry Question Paper for CBSE Class 12 - 2013  Chemistry Question Paper for CBSE Class 12 - 2015  CBSE Class 12 Chemistry Question Paper 2019 - Free PDF  CBSE Class 12 Chemistry Question Paper 2017 - Free PDF  CBSE Class 12 Chemistry Question Paper 2018 - Free PDF  Previous Year Question Paper for CBSE Class 12 Chemistry - 2014  Chemistry Question Paper for CBSE Class 12 - 2016 Set 1 E  Chemistry Question Paper for CBSE Class 12 - 2016 Set 1 S  HC Verma Class 12 Physics Part-2 Solutions for Chapter 29 - Electric Field and Potential  NCERT Solutions for Class 12 Physics Chapter 2  NCERT Solutions for Class 12 Physics Chapter 2 Electrostatic Potential and Capacitance in Hindi  NCERT Solutions for Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements in Hindi  NCERT Solutions for Class 12 Chemistry Chapter 8 The d and f Block Elements in Hindi  NCERT Solutions for Class 12 Chemistry Chapter 1 The Solid State in Hindi  NCERT Solutions for Class 12 Chemistry Chapter 5 Surface Chemistry in Hindi  NCERT Solutions for Class 12 Chemistry Chapter 7 The p-Block Elements In Hindi  NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry Some Basic Principles and Techniques In Hindi  NCERT Solutions for Class 11 Chemistry Chapter 3 Classification of Elements and Periodicity in Properties In Hindi  