[Shah]

i have a read a lot and still couldn't understand how does a PH meter work, so could anybody explain it in a simple way. In fact, the point is that how could we measure a voltage in a neutral solution (when an acid is dissociated, the solution would contain both anions and cations in equal amount, hence it would be neutral)

Also, i couldn't understand calibration and the purpose of doing it.

please help and thanks

[Shah]

can anybody post a site to explain simply and clearly what i am asking about?

aren't acidic and basic solutions neutral ?

[typhoon2028]

read here
http://en.wikipedia.org/wiki/PH_meter

Also, it is not PH.  It should read pH.

[Shah]

frankly what is written in Wikipedia is unclear and poorly illustrated. so can u give me other source

[JGK]

In this situation "Google" Is your friend

[Shah]

Anyway, can anybody answer this point please: how could we measure a voltage in a neutral solution (when an acid is dissociated, the solution would contain both anions and cations in equal amount, hence it would be neutral)
aren't acidic and basic solutions neutral?

[typhoon2028]

"Frankly" if you read and perform some critical thinking, you may get the bright idea to search "glass electrode."  Wikipedia appears to have a good explanation as well as a picture.

I think you are confusing electrical charge, ion balance, and acidity. 

[rabolisk]

Metals are neutral, but they conduct electricity, do they not?

[Shah]

in Wikipedia it is written: In a neutral solution the pH probe would generate 0v. An acidic sample would generate a positive voltage proportional to the ionic strength of the sample being measuring.

this is confusing me. Aren't acidic solution electrically neutral, So why is there a voltage?

[rabolisk]

They mean neutral in the sense of acidity/basicity.

[Shah]

i have read that a pH meter is a galvanic measurement circuit which is formed by connecting the measuring electrode (half-cell potential) and the reference electrode (half-cell potential) to the signal input of the measuring device. At the reference electrode there is a solid/solution interface, where a chemical reaction takes place. This enables an electrical current to flow through the measuring device.

My question is: Can you give me the chemical reactions taking place at each electrode of the pH meter? i.e between which ions is the reaction occurring which that is leading to electron flow allowing us to measure the voltage and deduce the pH?

[Arkcon]

I have missed this topic for over a year, however, for completeness, Wikipedia does have a very through article on the topic of the glass electrode: http://en.wikipedia.org/wiki/Glass_electrode#Construction