Question

For the cell prepared from electrodes A and B;
Electrode $A:C{r}_2{O}_7^{2-}|C{r}^{3+},E_{red}^o=1.33$V and
Electrode $B:F{e}^{3+}|F{e}^{2+},E_{red}^o=0.77$V
Which of the following statements is correct?

• A. The electrons will flow from B to A when connections are made
• B. The standard EMF of the cell will be $0.56$V
• C. A will be a positive electrode
• D. All of these

Answer 1

The correct option is D All of these

In an electrochemical cell the one which is having higher reduction potential acts as Anode and the one with lower reduction potential acts as cathode.

Here, $A:C{r}_2{O}_7^{2-}|C{r}^{3+}$acts as anode and $B:F{e}^{3+}|F{e}^{2+}$ acts as cathode.

So, the electrons will flow from cathode to anode i.e. from B to A.

We know that,

$E_{cell}^0$=$E_{cathode}^0$-$E_{anode}^0$

$⟹1.33-0.77=0.56V$

As ,A is cathode and hence is a positive electrode.