Voltaic Cells with Liquid Junction—The Practical Kind

There are two basic ways a cell may be set up, either without or with a salt bridge. The first is called a cell without liquid junction An example of a cell of this type would be 

The cell reaction would be (half-reaction)nght (half-reaction)ieft (to give a positive Eceii and the spontaneous reaction), or 

Cells without liquid junction are always used for the most accurate measurements because there are no uncertain potentials to account for and were used for measuring the pH of NIST standard buffers (see below). However, there are few examples of cells without liquid junction (sometimes called cells without transference), and these are inconvenient to use. Therefore, the more convenient but less accurate cells with liquid junction are most commonly used. 

It is possible to constiuct a cell without a salt bridge. For practical purposes, this is rai e because of the tendency of the reference electrode potential to be influenced by the test solution. 

This cell is used to accurately measure the pH of standard buffers. See Section 13.12. 

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VOLTAIC CELLS WITH LIQUID JUNCTION—THE PRACTICAL KIND... 

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