Nernst equation and its applications — NEET & JEE Questions

Question 1 · difficulty L1 · recall

At 298 K, which form of the Nernst equation is correct for a cell reaction involving $n$ electrons and reaction quotient $Q$?

• A. $E=E^\circ-\frac{0.0591}{n}\log Q$
• B. $E=E^\circ+\frac{0.0591}{n}\log Q$
• C. $E=E^\circ-0.0591n\log Q$
• D. $E=E^\circ+\frac{n}{0.0591}\log Q$

Question 2 · difficulty L2 · understanding

For a concentration cell made from identical electrodes and the same redox couple at different concentrations, what is the standard cell potential $E^\circ_{cell}$?

• A. $0$
• B. $0.0591\,\text{V}$
• C. $1.00\,\text{V}$
• D. It depends on the two concentrations

Question 3 · difficulty L2 · understanding

At 298 K, if the reaction quotient $Q$ for a galvanic cell is less than 1, how does its cell potential compare with $E^\circ_{cell}$?

• A. $E_{cell}>E^\circ_{cell}$
• B. $E_{cell}<E^\circ_{cell}$
• C. $E_{cell}=E^\circ_{cell}$ for every value of $Q$
• D. The sign cannot be predicted

Question 4 · difficulty L2 · understanding

In the Nernst equation for a complete cell reaction, what does $n$ represent?

• A. The total stoichiometric coefficient of all species
• B. The number of moles of electrons transferred in the balanced cell reaction
• C. The number of ions present in the salt bridge
• D. The oxidation number of the cathode metal

Question 5 · difficulty L3 · application

For the cell $\text{Zn}|\text{Zn}^{2+}(0.010\,M)||\text{Cu}^{2+}(1.0\,M)|\text{Cu}$ at 298 K, $E^\circ_{cell}=1.10\,\text{V}$. What is $E_{cell}$? Use $0.0591\,\text{V}$ in the Nernst equation.

• A. $1.04\,\text{V}$
• B. $1.10\,\text{V}$
• C. $1.16\,\text{V}$
• D. $1.22\,\text{V}$

Question 6 · difficulty L3 · application

A cell reaction transfers 2 electrons and has $E^\circ_{cell}=0.1182\,\text{V}$ at 298 K. Approximately what is its equilibrium constant $K$?

• A. $10^2$
• B. $10^4$
• C. $10^6$
• D. $10^8$

Question 7 · difficulty L3 · application

For the half-cell $\text{Cu}^{2+}+2e^-\rightarrow\text{Cu}$, $E^\circ=0.34\,\text{V}$. What is the electrode potential at 298 K when $[\text{Cu}^{2+}]=0.010\,M$?

• A. $0.281\,\text{V}$
• B. $0.310\,\text{V}$
• C. $0.340\,\text{V}$
• D. $0.399\,\text{V}$

Question 8 · difficulty L3 · application

For the reduction $\text{Fe}^{3+}+e^-\rightarrow\text{Fe}^{2+}$, $E^\circ=0.77\,\text{V}$. At 298 K, $[\text{Fe}^{2+}]=1.0\,M$ and $[\text{Fe}^{3+}]=0.10\,M$. What is $E$?

• A. $0.711\,\text{V}$
• B. $0.770\,\text{V}$
• C. $0.829\,\text{V}$
• D. $0.652\,\text{V}$

Question 9 · difficulty L4 · application

For the cell $\text{Zn}|\text{Zn}^{2+}(0.10\,M)||\text{Cu}^{2+}(0.0010\,M)|\text{Cu}$ at 298 K, $E^\circ_{cell}=1.10\,\text{V}$. What is the cell potential?

• A. $0.982\,\text{V}$
• B. $1.041\,\text{V}$
• C. $1.159\,\text{V}$
• D. $1.218\,\text{V}$

Question 10 · difficulty L4 · application

A hydrogen electrode at 298 K has hydrogen gas at $1\,\text{bar}$ and electrode potential $-0.2364\,\text{V}$ relative to the standard hydrogen electrode. What is the pH of the solution?

• A. 2
• B. 4
• C. 6
• D. 8