Electrochemical cells, Chemistry

Assignment Help:

ELECTROCHEMICAL CELLS

Galvanic and electrolytic cells:

The difference between potential of the two metals results in a potential difference (also called a electromotive force or voltage, emf) between the two half-cells. That can be measured by means of a high impedance voltmeter which measures the driving force or voltage for reaction without allowing current to flow from which can be calculated thermodynamic data. Alternatively the reaction can be allowed to proceed by connecting the two half-cells by circuit (a wire or a resistor) and allowing the current to flow. These are both examples of galvanic cells, where the chemical reaction occurs. Electrons flow from the electrode with the most negative potential (the anode, where oxidation occurs) to that with the most positive potential (the cathode, where reduction occurs). The salt bridge (or porous glass frit) allows ions to transfer into each half-cell. That flow counteracts the imbalance of charge that would develop in each half cell as electrons (e-) pass from one electrode to the other, which would inhibit the reaction. The need for a frit or salt bridge is avoided if both half cells can share a common electrolyte. It is a special case, where all redox active ions in the solution react at one half cell electrode only and therefore do not have to be separated from the other electrode.

1024_electrochemical cells.png

Fig. 1. Examples of (a) an electrolytic cell incorporating a salt bridge; (b) a galvanic cell incorporating a porous frit.

Other half-cell reactions:

The metal-insoluble salt electrode consists of a metal M coated with a porous insoluble salt MX in a solution of X-. A good example is the silver/silver chloride electrode (Fig. 2a) for which the half-cell reaction is, where the reduction of solid silver chloride produces solid silver and releases chloride ion into solution.

 

 

2232_other half reaction.png

Fig. 2. (a) The silver/silver chloride half-cell; (b) the ferric (Fe3+)/ferrous (Fe2+) half-cell; (c) the

fluorine/fluoride ion half-cell.


Related Discussions:- Electrochemical cells

What are conjugate acid and conjugate bases?, when H+ is removed from any c...

when H+ is removed from any compound it forms conjugate acid. the addition of H+ ion gives conjugate base.

Calculate the standard entropy change, (a) Discuss, with the aid of diagram...

(a) Discuss, with the aid of diagrams, and with suitable examples, the chemistry (including half-cell reactions), construction and principles of the following electrode types: (

Which group of elements is called alkaline earth metals, 1st A group becaus...

1st A group because the oxides and hydrides are alkaline in nature.

Chemical combination, the verification of the law of chemical combination

the verification of the law of chemical combination

Effectiveness of blanching by peroxidase inactivity test, Q. Effectiveness ...

Q. Effectiveness of blanching by peroxidase inactivity test? • check the adequacy of the blanching process, • appreciate the importance of time-temperature relationship i

Nonstoichiometry, Whereas a pure molecular species has a definite stoichiom...

Whereas a pure molecular species has a definite stoichiometry, this is not often true for solids. Defects in crystals will include vacancies (atoms missing from their expected site

Quantum mechanical model of the atom, Q. Quantum Mechanical Model of the At...

Q. Quantum Mechanical Model of the Atom? Ans: Using quantum mechanics, scientists realized that the exact location of an electron could not be determined. Instead, only the p

Law of crystallography, how law of crystallography helps in the study of cr...

how law of crystallography helps in the study of crystal structure

Find the number of intensive variables, Find the number of intensive variab...

Find the number of intensive variables? Consider the lime-kiln process CaCO 3 (s) → CaO (s) + CO 2 (g) Find the number of intensive variables that can be varied independen

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd