Cells and half cells

2,647 views

Published on

Published in: Education
0 Comments
5 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
2,647
On SlideShare
0
From Embeds
0
Number of Embeds
9
Actions
Shares
0
Downloads
31
Comments
0
Likes
5
Embeds 0
No embeds

No notes for slide

Cells and half cells

  1. 1. Chemistry<br />Cells and Half Cells<br />
  2. 2. Definition<br />An electrochemical cell controls the electron transfer to produce electrical energy<br />A half cell comprises of an element in two oxidation states<br />The electrode potential of the half cell indicates its tendency to lose or gain electrons<br />
  3. 3. Example<br />
  4. 4. Cells from metal/metal ion half cells<br /><ul><li>The difference in electrode potential is measured with a voltmeter
  5. 5. The wire allows electrons to be transferred between the half cells
  6. 6. The salt bridge allows ions to be transferred between the half cells
  7. 7. A salt bridge can be made out of a strip of filter paper soaked in an aqueous solution of an ionic compound that doesn’t react with the half cell solutions
  8. 8. Usually aqueous KNO₃ (aq) or NH₄NO₃ (aq) is used</li></li></ul><li>Non-metal/non-metal ion half cells<br />Problem<br />There is no electrode to connect wire to<br />Solution<br />A platinum electrode is placed in the solution<br />The platinum doesn’t react at all<br />Its purpose is to allow the transfer of electrons in and out of the half cell<br />The surface of the platinum electrode is coated with platinum black<br />
  9. 9. Metal ion/metal ion half cell<br />Fe²⁺ (aq) + e⁻ ↔ Fe³⁺ (aq)<br />Cell is made up of:<br />A solution containing Fe²⁺ (aq) and Fe³⁺ (aq) ions of the same concentration<br />Also known as Equimolar<br />Inert platinum electrode with a connecting wire<br />

×