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How a pH meter works!

today I'm going to talk about the pH

electrode and how it works let's go

ahead and identify the parts every pH

electrode has glass ball that comes in

contact with the solution there is a

wire that conducts electricity and is on

the inside of the electrode which is

directly connected to an internal

microchip surrounding this wire is an

electrical conductive solution called an

electrolyte solution the solution is

normally a KCl potassium chloride

solution of a concentration near 3.5

molar the KCl solution can be a gel or a

liquid depending on its design use this

kcl solution leaks out of the glass bulb

through a junction at a specific rate

example cloth junction equals 14 micro

liter per hour there are three basic

types of junctions to allow for the

leaking of the electrolyte KCl solution

into your testing solution ceramic

Junction normally used in large sized

particulate solutions with low

concentration for example city water

cloth Junction normally used in medium

to large sized particulate with high

concentrated solutions for example plant

nutrient solutions open junction

normally used in small to large sized

particulate with high concentration

solution for example wine on the bottom

layer of the glass bulb you have a gel

layer that must be hydrated for proper

use you will have your glass bulb

submerged in a testing or storage

solution that will submerge the junction

for this example we are going to show

you H+ hydrogen ions HOH water molecule

o H hydroxide ion pH stands for

potential hydrogen ions when measuring

the pH of a solution you are measuring

the number of hydrogen ions in that

solution a large number will create an

acid solution and a low number will

represent a base solution

now we are going to show how all these

parts work together to get you a pH

reading in a few seconds submerge your

pH electrode so that the junction is in

contact with your solution the

electrolyte will begin to leak out of

the junction at 40 micro liters per hour

a millivolt electrical charge is

supplied to the wire from the Meters

battery the millivolt charge will float

down the wire through the glass bulb

electrifying the hydrated gel layer the

hydrogen ions in your solution will

migrate toward and attach themselves to

the hydrated gel layer the number of

hydrogen ions inside of the glass bulb

versus the number of hydrogen ions

attached to the gel layer will

ultimately decide your solutions pH

value this is dependent on the millivolt

charge transmitted through the hydrogen

ions from your solution if more hydrogen

ions are attached to the gel layer than

are inside the glass bulb this will

create a low pH value called an acid if

less hydrogen ions are attached to the

gel layer than are inside the glass bulb

this will create a high pH value called

a base equal hydrogen ions on both sides

of the gel layer and glass bulb will

create a neutral pH value this is

created by a millivolt charge close to

zero based on the number of hydrogen

ions in this example we would expect

about an eight millivolt charge this 8

millivolt charge needs to re-enter the

pH electrode to be transmitted to the

microchip so the nearest equation can

provide a pH value the junction type

leaking 3.5 molar KCl a high salt

electrical conductive solution into your

example will now serve as a liquid wire

to transmit the 8 millivolt signal

through the liquid wire Junction metal

wire and into the microchip so the

Nernst equation can generate a pH value

this concludes how your pH value is

created with a millivolt charge pinch

electrode thank you for watching an

educational copywrited video from ph

professor