The haf reaction occuring in the standard hydrogen electrode "SHE" is 2H+ (aq) +2e- <=> H2...

The haf reaction occuring in the standard hydrogen electrode "SHE" is
2H⁺ (aq) +2e- <=> H₂ (g)

a) What is the EMF for this half-cell?
b) How is the EMF value listed in part (a) above for the standard ydrogen electrode measured?
c) Why do we need a "standard reference electrode" like this hydrogen half-cell?
d) How is SHE used to determine unknown half-cell voltages?

Solutions

Expert Solution

We know emf of 2H⁺ (aq) +2e- <=> H₂ (g)

This half reaction is 0 V

As we go above the EMV table we find that strength of oxidizing agent is increased.

And strength of reducing agent is decreased.

So value of EMF become more positive as we go above the EMF table.

EMF of Standard hydrogen electrode is set at 0 V or we can say that is reference point. All the EMF values are related to the this half reaction. To measure emf of half cell it become easy when we use the SHE as a reference electrode since SHE has 0 V so whatever measurement we get that is for the half cell.

For example,

We have to measure potential of half cell of Zn then we connect this metal electrode to the SHE and we get EMF. That emf half cell of Zn

We get total cell potential by measuring EMF of cell. We know EMF of SHE is 0 V

so whatever the potential of cell ( total ) that will be the potential of unknown half cell.

queen_honey_blossom answered 10 months ago

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