Explain construction and working of glass electrode.

2.B] Explain construction and working of glass electrode.


construction and working of glass electrode:

Glass electrode is pH sensitive electrode which can selectively detect and measures H+ ions in a system. Thus, it is widely used for pH measurements.

Glass electrode consists of a long glass tube with a thin-walled glass bulb at one end as shown in figure. The bulb contains 0.1M HCl. Ag/AgCl electrode (internal reference electrode) is placed in the solution and connected by a platinum wire for external contact.

The electrode is represented as,

Ag│ AgCl │ 0.1 M HCl │ Glass membrane

Glass electrode


When the glass electrode is dipped in the test solution (xM), the Na+ ions of the glass membrane are exchanged for H+ ions of the solution inside & outside. The reaction is ion-exchange.

The boundary potential Eb is established due to the above reaction. The glass electrode potential EG is given by.

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