2.
The pH meter was invented in 1934 by the American chemist Arnold O.
Beckman (1900-2004) to measure the sourness of lemons
A simple and speedy device to measure the acidity and alkalinity of a fluid.
A pH meter acts as a volt meter that measures the electrical potential
difference between a pH electrode and a reference electrode and displays the
result in terms of the pH value of the solution in which they are immersed.
INTRODUCTION
3.
The logarithm of the reciprocal of hydrogen-ion concentration in
gram atoms per litre; provides a measure on a scale from 0 to 14 of the
acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is
more basic and less than 7 is more acidic);
pH
(Potential of Hydrogen)
The formal definition of pH is the
negative logarithm of the hydrogen ion
activity.
pH = -log[H+]
4. An acid can be defined as a proton donor, a chemical that increases the
concentration of hydrogen ions in solution. HCL----------H+
+ CL-
A corrosive liquid with a pH less than 7; a solution of in water of a substance
that releases hydrogen ions
A base can be defined as a proton acceptor, a chemical that reduces the
concentration of hydrogen ions in solution. KOH……..K+
+ OH-
A corrosive liquid with a pH greater than 7; a solution of in water of a
substance that releases hydroxyl ions
Acids and Bases
5.
A pH measurement system consists of
High input meter
2 probes
Buffer powder/capsules for calibration
Distil water
pH Meter
7. 1.Glass electrode: It consists thin bulb of special glass
blown(lithium) at the end of the glass tube,and the bulb is filled with
dilute acid for example decinormal HCL acid connected to a silver
chloride electrode
2.Calomel electrode: It consists of a glass tube containing
saturated KCL connected to platinum wires through mercury (mercury
chloride)
3.Reference junction: typically made of porous ceramic or porus teflon
Probe 1 consists of 3 parts (2 electrodes)
ELECTRODE: A conductor used to make electrical contact with some
part of a circuit
Probe 1
1
2
3
8. Probe 2
CHECKING FOR SOLUTION’S
TEMPERATURE
2 PROBES ARE CONNECTED
TO HIGH INPUT pH
READING MTER
9.
The act of checking or adjusting (by comparison with a standard) the accuracy of a measuring instrument
BUFFER
POWDER/CAPSULES
11.
A voltmeter in the probe measures the difference between the voltages of the
two electrodes.
The meter then translates the voltage difference into pH and displays it on
the screen.
Before taking a pH measurement the meter must be calibrated using a
solution of known pH.
pH Meter
12.
Temperature compensation is connected within the instrument
because pH electrodes are temperature sensitive.
Temperature compensation only corrects for the change in the
output of the electrode, not for the change in the actual solution.
Buffers are solutions that have constant pH values and the ability
to resist changes in pH.
They are used to calibrate the pH meter.
Temperature and Buffers
13.
1.The 2 probes should connect to pH reading meter
Connect the power pack of 230v to the pH meter
Dip the electrode in a standard solution of pH and set the temparature and take reading
(The 1st probe should be calibrate with different buffer solutions for rule out the errors of the
electrode(buffer solution:buffer powder + distil water).Then should check the solution
temperature with 2nd
probe)
Remove buffers wash and wipe the electrode and dip it in the desireble solution and take
the reading.
METHOD OF USING
14.
An electrical potencial devolops when one liquid is brought into contact with
another one ,but a membrane is needed to keep such liquid aparts
A ph meter measures essentially the electro – chemicall potencial between a
known liquid inside the glass electrode and unknown liquid outside
Because the thin glass bulb allows mainly the agile and small hydrogen ions
to interact with the glass,the glass electrode measures the electro chemical
potential of hydrogen ions.
How a pH meter works
15. PH EXAMPLE
0 HCL
1 GASTRIC JUICES
2 LEMON JUICE
3 ORANGE JUICE
4 COLA
5 COFEE
6 RAIN WATER
7 PURE WATER
8 SEA WATER
9 BAKING SODA
10 ANTACIDS
12 DETERGENT
13 OVEN CLEANER
14 NAOH
17.
THANK U
REFERENCES:
RESEARCH METHDOLOGY FOR AYURVEDIC SCHOLARS-DR.S.SURESHBABU
TABER’S CYCLOPEDIC MEDICAL DICTIONARY EDITION 20
INTERNET
IMAGES COLLECTED FROM RASASHASTRA DEPT SDMCAH
