The meaning of pH
pH is a unit of measure that elaborate degree of acidity level or alkalinity of a liquid. The Unit of pH is measured at scale from 0 till 14. Term of pH indigenous to "p", mathematics symbol from negative logarithm, and " H", chemistry symbol for Hidrogen. Formal definition about pH is negative logarithm from ion activity Hydrogen.
pH=-log[H+]
pH are formed from quantitative information that expressed by level of acidity degree or related to basa ion activity hydrogen. Value pH from an unsure is comparison between ion concentration hydrogen [H+] with concentration of hydroxyl ion [OH-]. If concentration H+ bigger than OH-, significant is called acid that is mean the value of pH is less than 7. If concentration OH bigger than H+, significant is called basa, with a value of pH bigger than 7. If concentration H+ equal to OH- then significant is called neutral material. Acid and basa have ion free of hydrogen and alkali. The value of ion concentration H+ of liquid called acidity degree. To state acidity degree a sollution is weared understanding pH.
According text below, then determined:
- If value pH = pOH = 7, then the liquid has character of neutral.
- If value pH <7, then the liquid has character of acid
- If value pH > 7, then the liquid has character of basic.
- At room temperature: pKw = pH + pOH = 14 .
pH is a unit of measure that elaborate degree of acidity level or alkalinity of a liquid. The Unit of pH is measured at scale from 0 till 14. Term of pH indigenous to "p", mathematics symbol from negative logarithm, and " H", chemistry symbol for Hidrogen. Formal definition about pH is negative logarithm from ion activity Hydrogen.
pH=-log[H+]
pH are formed from quantitative information that expressed by level of acidity degree or related to basa ion activity hydrogen. Value pH from an unsure is comparison between ion concentration hydrogen [H+] with concentration of hydroxyl ion [OH-]. If concentration H+ bigger than OH-, significant is called acid that is mean the value of pH is less than 7. If concentration OH bigger than H+, significant is called basa, with a value of pH bigger than 7. If concentration H+ equal to OH- then significant is called neutral material. Acid and basa have ion free of hydrogen and alkali. The value of ion concentration H+ of liquid called acidity degree. To state acidity degree a sollution is weared understanding pH.
According text below, then determined:
- If value pH = pOH = 7, then the liquid has character of neutral.
- If value pH <7, then the liquid has character of acid
- If value pH > 7, then the liquid has character of basic.
- At room temperature: pKw = pH + pOH = 14 .
scale of pHMeasurement pH in harsh diffraction can do with conducted with paper pH or paper indicator pH method, with color transformation at which variety of pH level. This Indicator have limitation at level of measurement accuration, and can happen mistake of colour perception that caused the liquid sample has character chromatic sample or turbid sample.
Measurement of pH more accurate usual conducted by using pH metre. System measurement pH have three part are measurement electrodes pH, electrode refference,and high impedance grader. pH electrode can be assumed as battery, with which has variety of voltage measurement result from pH liquid measured.
History of pH metre
History in measured fluid acidity was in electric started in 1906 when Max Cremer in its study about fluid relation/link (interaction between hydrogen and solid substance) and found in the reality relation/link between fluid can be studied with to observe float a bubble from thin glass one fluid that place inside and outside. That make a measureable electrical tension. This Idea has been taken furthermore by Fritz Haber (that find ammonia synthesis and imitat fertiliser) and Zygmunt Klemsiewicz that find that bulb/glass bubble (that he name glass electrode) can be used to measure hydrogenic ions activity that followed a logarithmic function.
Then, Dane biochemist Soren Sorensen finds scale pH in 1909. Because sensitivity in very high glass wall, range from 10 till 100 Mega-Ohms, voltage of glass electrode is will never measured accurately till electron tube has been found. Then, the discovery of field effect transistor (field-effect transistors FETs) and integrated circuit ( ICs) by lighten temperature, make it maybe to measure that voltage of glass electrode accurately. Voltage that produced by one pH unit (for example just from pH=7.00 - 8.00) characteriscally around 60 mV (mili volt). Now Ph Meter that consisted of microprocessor required just for temperature correction and calibrate. Nevertheless, modernpH metre still has insuffiency, that is slow change, that is important issue in determining valid scale.
pH metre for commercial usage first time produced by Radiometer in 1936 in Denmark and Arnold Orville Beckman from United States. Discovery is referred when Beckman become assisten professor chemistry in California Institute of Technology, he tells to get quick and accurate method for acid measurement from lemon juice that produced by California Fruit Growers Exchange (Sunkist). Its discovery result bring him to found Beckman Instruments Company (now Beckman Coulter).
Principle of pH metre
In principle measurement of a pH is based on potential chemistry electro that occured between liquid that existed in glass electrode (membrane glass) that has been known with liquid that existed outside unknown glass electrode. This condition because of thin layer from glass bubble will interact with ion hydrogen that its size relative of small and active, glass electrode will measure potential electrochemical from hydrogen ion or it’s called potential of hydrogen. To complete electrical circuit is required a comparator electrode. As note, the tool is not measure electric current but only measure electric tension.
Measurement of pH more accurate usual conducted by using pH metre. System measurement pH have three part are measurement electrodes pH, electrode refference,and high impedance grader. pH electrode can be assumed as battery, with which has variety of voltage measurement result from pH liquid measured.
History of pH metre
History in measured fluid acidity was in electric started in 1906 when Max Cremer in its study about fluid relation/link (interaction between hydrogen and solid substance) and found in the reality relation/link between fluid can be studied with to observe float a bubble from thin glass one fluid that place inside and outside. That make a measureable electrical tension. This Idea has been taken furthermore by Fritz Haber (that find ammonia synthesis and imitat fertiliser) and Zygmunt Klemsiewicz that find that bulb/glass bubble (that he name glass electrode) can be used to measure hydrogenic ions activity that followed a logarithmic function.
Then, Dane biochemist Soren Sorensen finds scale pH in 1909. Because sensitivity in very high glass wall, range from 10 till 100 Mega-Ohms, voltage of glass electrode is will never measured accurately till electron tube has been found. Then, the discovery of field effect transistor (field-effect transistors FETs) and integrated circuit ( ICs) by lighten temperature, make it maybe to measure that voltage of glass electrode accurately. Voltage that produced by one pH unit (for example just from pH=7.00 - 8.00) characteriscally around 60 mV (mili volt). Now Ph Meter that consisted of microprocessor required just for temperature correction and calibrate. Nevertheless, modernpH metre still has insuffiency, that is slow change, that is important issue in determining valid scale.
pH metre for commercial usage first time produced by Radiometer in 1936 in Denmark and Arnold Orville Beckman from United States. Discovery is referred when Beckman become assisten professor chemistry in California Institute of Technology, he tells to get quick and accurate method for acid measurement from lemon juice that produced by California Fruit Growers Exchange (Sunkist). Its discovery result bring him to found Beckman Instruments Company (now Beckman Coulter).
Principle of pH metre
In principle measurement of a pH is based on potential chemistry electro that occured between liquid that existed in glass electrode (membrane glass) that has been known with liquid that existed outside unknown glass electrode. This condition because of thin layer from glass bubble will interact with ion hydrogen that its size relative of small and active, glass electrode will measure potential electrochemical from hydrogen ion or it’s called potential of hydrogen. To complete electrical circuit is required a comparator electrode. As note, the tool is not measure electric current but only measure electric tension.
Scheme the Electorde of pH metrepH metre will measure potential electrics (at picture clockwise) between merkuri Cloride (HgCl) at comparator electrode and potassium chloride (KCl) that is liquid in glass electrode and potential between liquid and silver electrode. But potential between unknown sampel and glass electrode can change hung up the sample, in consequence, must conducted calibrate use liquid that equivalen another to specify value of pH.
Comparator Electrode calomel consist of glass tube containing potassium kloride (KCl) that is electrolyte which occured contact with mercuri chloride (HgCl) at top liquid KCl. This glass tube is fragile (breakable) so that to connect it used ceramic or other same thing materials. This sort of electrode is not easy contaminable by metal and unsure natrium.
Glass electrode consist of sturdy glass tube that connected to thin glass bubble. Inside there’s liquid KCl as buffer pH 7. Silver Electrode that the top of it is silver kloride (AgCl2) connected into that liquid. For meminimalisir influence electric that unwanted, the tool must covered by a layer of protector paper that usually existed at the inside glass electrode.
At most modern pH metre has been provided with thermistor temperature that is a tool to correction influence temperature. Between comparator electrode and glass electrode have been compiled in one unity.
Comparator Electrode calomel consist of glass tube containing potassium kloride (KCl) that is electrolyte which occured contact with mercuri chloride (HgCl) at top liquid KCl. This glass tube is fragile (breakable) so that to connect it used ceramic or other same thing materials. This sort of electrode is not easy contaminable by metal and unsure natrium.
Glass electrode consist of sturdy glass tube that connected to thin glass bubble. Inside there’s liquid KCl as buffer pH 7. Silver Electrode that the top of it is silver kloride (AgCl2) connected into that liquid. For meminimalisir influence electric that unwanted, the tool must covered by a layer of protector paper that usually existed at the inside glass electrode.
At most modern pH metre has been provided with thermistor temperature that is a tool to correction influence temperature. Between comparator electrode and glass electrode have been compiled in one unity.
Modern Electrode pH metreUsed Method Calibration
Before pH metre is used, pH metre is must calibrated use standard pH or often called pH buffer. Standard pH is liquid that value of it pH has been known in each temperature change. Standard pH is liquid buffer pH where its value constant relative and is not rapidly changed.
Procedure calibrates pH metre are :
1. Prepare buffer pH 7 and buffer pH 4
2. Open plastic cover electrode
3. Rinse electrode with water DI (De Ionisasi/ free water ion) and dry it by using tissue paper
4. Turn on pH metre by pressing ON/OFF button.
5. Enter the electrode into liquid buffer pH 7
6. Press CAL button two times, turn around electrode so that to liquid buffer homogeny
7. Let it a few moments till value that at display is not changed
8. Press CAL button once again, and let text CAL at disply stop blinking
9. Lift the electrode from pH 7 buffer liquid, then rinse with DI water several times and dry it with tissue paper
10. Enter Electrode into pH 4 buffer liquid
11. Press CAL button two times, turn around electrode so that buffer liquid homogeny
12. Let it a few moments till value that at display is not changed
13. Press CAL button once again, and let text CAL at disply stop blinking
14. Lift the electrode from pH 4 buffer liquid, then rinse with DI water several times and dry it with tissue paper
15. At underside of screen will emerge number 7 and number 4 that show pH metre has been calibrated with buffer pH 7 and buffer pH 4
16. pH metre has been ready to used
Measurement of pH liquid
After pH metre is calibrated then pH metre has been ready to used. Usually calibrate suggested one day before use it.
Measurment procedure :
1. Prepare the liquid sample which will check the value of pH
2. If the liquid sample is heat, let it cool till temperature equal to temperature when calibrate. The example if calibrate at temperature 20°C then measurment are conducted at temperature 20°C.
3. Open the electorde plastic cover, rinse with DI water and dry it by using tissue paper.
4. Turn on the pH metre by pressing ON/OFF button.
5. Enter the electrode into sample, then turn arounds in order to liquid homogeny.
6. Press MEAS button to start measurement, at screen will emerge text HOLD that blinking.
7. Let it till the text HOLD at secreen stop blinking.
8. Value of pH that showed at screen is value of pH liquid that in check
9. Turn off pH metre by press ON/OFF button
Maintenance of pH metre
pH metre must be done periodic treatment. Its maintenance include :
a) Battery, battery replacement is conducted if at screen emerge text low battery
b) Electrode, electrode cleaning can be conducted periodic every minimal once a week. Its cleaning uses liquid HCL 0.1 N (liquid) by soaked for 30 minute, then cleaned with DI water.
c) Storage, when not used, the electrode especially part of glass bubble always must in damp situation. In consequence, electrode storage are suggested always soaked with DI water. Sotage in dry condition will cause membrane on glass electrode bubble will breakable and its read inaccurate.
d) Storage Temperature. When kept, pH metre may not at room temperature that heat because the censor temperature will broken quickly.
Following there is video of usage way pH metre, just directly click here.
Picture and Description
Before pH metre is used, pH metre is must calibrated use standard pH or often called pH buffer. Standard pH is liquid that value of it pH has been known in each temperature change. Standard pH is liquid buffer pH where its value constant relative and is not rapidly changed.
Procedure calibrates pH metre are :
1. Prepare buffer pH 7 and buffer pH 4
2. Open plastic cover electrode
3. Rinse electrode with water DI (De Ionisasi/ free water ion) and dry it by using tissue paper
4. Turn on pH metre by pressing ON/OFF button.
5. Enter the electrode into liquid buffer pH 7
6. Press CAL button two times, turn around electrode so that to liquid buffer homogeny
7. Let it a few moments till value that at display is not changed
8. Press CAL button once again, and let text CAL at disply stop blinking
9. Lift the electrode from pH 7 buffer liquid, then rinse with DI water several times and dry it with tissue paper
10. Enter Electrode into pH 4 buffer liquid
11. Press CAL button two times, turn around electrode so that buffer liquid homogeny
12. Let it a few moments till value that at display is not changed
13. Press CAL button once again, and let text CAL at disply stop blinking
14. Lift the electrode from pH 4 buffer liquid, then rinse with DI water several times and dry it with tissue paper
15. At underside of screen will emerge number 7 and number 4 that show pH metre has been calibrated with buffer pH 7 and buffer pH 4
16. pH metre has been ready to used
Measurement of pH liquid
After pH metre is calibrated then pH metre has been ready to used. Usually calibrate suggested one day before use it.
Measurment procedure :
1. Prepare the liquid sample which will check the value of pH
2. If the liquid sample is heat, let it cool till temperature equal to temperature when calibrate. The example if calibrate at temperature 20°C then measurment are conducted at temperature 20°C.
3. Open the electorde plastic cover, rinse with DI water and dry it by using tissue paper.
4. Turn on the pH metre by pressing ON/OFF button.
5. Enter the electrode into sample, then turn arounds in order to liquid homogeny.
6. Press MEAS button to start measurement, at screen will emerge text HOLD that blinking.
7. Let it till the text HOLD at secreen stop blinking.
8. Value of pH that showed at screen is value of pH liquid that in check
9. Turn off pH metre by press ON/OFF button
Maintenance of pH metre
pH metre must be done periodic treatment. Its maintenance include :
a) Battery, battery replacement is conducted if at screen emerge text low battery
b) Electrode, electrode cleaning can be conducted periodic every minimal once a week. Its cleaning uses liquid HCL 0.1 N (liquid) by soaked for 30 minute, then cleaned with DI water.
c) Storage, when not used, the electrode especially part of glass bubble always must in damp situation. In consequence, electrode storage are suggested always soaked with DI water. Sotage in dry condition will cause membrane on glass electrode bubble will breakable and its read inaccurate.
d) Storage Temperature. When kept, pH metre may not at room temperature that heat because the censor temperature will broken quickly.
Following there is video of usage way pH metre, just directly click here.
Picture and Description
Picture Description and Button pH metre1. Body of pH meter
2. Body of elektroda
3. Screen display
4. Electrode cable
5. Temperature censore display
6. MEAS button for measurement
7. MODE button for selected measurement mode
8. Set button for measurment setting
9. CAL button for calibration
10. CAL DATA for review data calibration that calibrated
11. ON/OFF button for Turn ON/Turn OFF
12. Data OUT button for output
13. ENTER button
14. Glass electrode
15. Comparison Electrode (reference)
Macam-macam pH Meter
1 komentar:
Nice blog great information...
Thanks for sharing...
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