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Questions and Answers
The reference electrode in a pH meter probe can lose ions through interactions with the surrounding environment.
The reference electrode in a pH meter probe can lose ions through interactions with the surrounding environment.
False
The external tube of a pH meter probe is filled with potassium chloride solution to prevent a loss of ions.
The external tube of a pH meter probe is filled with potassium chloride solution to prevent a loss of ions.
True
Hydrogen ions [H+] can pass through the glass membrane of the pH electrode.
Hydrogen ions [H+] can pass through the glass membrane of the pH electrode.
False
A pH meter typically has at least two calibration controls identified as Cal 1 and Cal 2.
A pH meter typically has at least two calibration controls identified as Cal 1 and Cal 2.
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Not all pH meters include an ON and OFF switch.
Not all pH meters include an ON and OFF switch.
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The glass bulb of the pH electrode is not covered with any material.
The glass bulb of the pH electrode is not covered with any material.
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The temperature control on a pH meter adjusts only the pH reading.
The temperature control on a pH meter adjusts only the pH reading.
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The mode selector on a pH meter includes a standby mode, which protects the electrodes from electrical currents.
The mode selector on a pH meter includes a standby mode, which protects the electrodes from electrical currents.
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The screen shows a calibration error if the electrode is not immersed properly.
The screen shows a calibration error if the electrode is not immersed properly.
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To eliminate air bubbles in the pH electrode, it is necessary to soak the electrode.
To eliminate air bubbles in the pH electrode, it is necessary to soak the electrode.
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A flashing battery indicator on the pH meter indicates that the batteries are functioning properly.
A flashing battery indicator on the pH meter indicates that the batteries are functioning properly.
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The automatic temperature control mode is necessary for all pH meters.
The automatic temperature control mode is necessary for all pH meters.
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A combined electrode integrates both a reference electrode and an internal electrode in the same body.
A combined electrode integrates both a reference electrode and an internal electrode in the same body.
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Cleaning the electrode can resolve slow response issues for the meter.
Cleaning the electrode can resolve slow response issues for the meter.
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Replacing the batteries is the solution when there is no signal on the pH meter screen due to incorrectly installed batteries.
Replacing the batteries is the solution when there is no signal on the pH meter screen due to incorrectly installed batteries.
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Two point calibration is ideal for everyday pH measurements.
Two point calibration is ideal for everyday pH measurements.
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The electrodes must always be stored in distilled water.
The electrodes must always be stored in distilled water.
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For accurate readings, it is important to rinse the electrode with distilled water between different solutions.
For accurate readings, it is important to rinse the electrode with distilled water between different solutions.
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The pH meter should be calibrated using a known pH solution only after it has been used sporadically.
The pH meter should be calibrated using a known pH solution only after it has been used sporadically.
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The lower extremity of the electrode should touch the bottom of the calibration beaker.
The lower extremity of the electrode should touch the bottom of the calibration beaker.
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A magnetic agitator can be used during pH testing if care is taken to avoid contact with the electrode.
A magnetic agitator can be used during pH testing if care is taken to avoid contact with the electrode.
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Buffer solutions have a variable pH even when contaminated.
Buffer solutions have a variable pH even when contaminated.
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The functions selector of the pH meter should be set to the pH position for calibration.
The functions selector of the pH meter should be set to the pH position for calibration.
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The pH reading from a meter is most accurate when viewed perpendicularly.
The pH reading from a meter is most accurate when viewed perpendicularly.
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The pH probe should be rinsed with distilled water before measuring a solution of unknown pH.
The pH probe should be rinsed with distilled water before measuring a solution of unknown pH.
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Calibrating the pH meter should be done after every single use.
Calibrating the pH meter should be done after every single use.
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General maintenance of the pH meter should be conducted every month.
General maintenance of the pH meter should be conducted every month.
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The pH meter must be turned off after measuring the last solution to ensure its longevity.
The pH meter must be turned off after measuring the last solution to ensure its longevity.
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After using the pH electrode, it should be stored immediately without rinsing.
After using the pH electrode, it should be stored immediately without rinsing.
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The equipment controls must be in good condition and activated without difficulty.
The equipment controls must be in good condition and activated without difficulty.
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The measuring electrode requires maintenance every six months.
The measuring electrode requires maintenance every six months.
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It is acceptable for the tip of the syringe to touch the inside of the electrode when filling it with KCI solution.
It is acceptable for the tip of the syringe to touch the inside of the electrode when filling it with KCI solution.
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The pH electrode can be soaked in a diluted domestic bleach solution for the removal of deposits and bacteria.
The pH electrode can be soaked in a diluted domestic bleach solution for the removal of deposits and bacteria.
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Rinsing the electrode after cleaning should be done with deionised water before refilling the reference electrode.
Rinsing the electrode after cleaning should be done with deionised water before refilling the reference electrode.
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It is recommended to strike the electrode gently to check its durability.
It is recommended to strike the electrode gently to check its durability.
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One of the methods for cleaning oil and grease off the pH electrode is to use methyl alcohol.
One of the methods for cleaning oil and grease off the pH electrode is to use methyl alcohol.
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Cleaning with 1% pepsin and 0.1 M HCl is recommended for protein deposits on the pH electrode.
Cleaning with 1% pepsin and 0.1 M HCl is recommended for protein deposits on the pH electrode.
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The plasma pH of a healthy individual typically measures between 6.35 and 6.45.
The plasma pH of a healthy individual typically measures between 6.35 and 6.45.
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The pH meter can be used in fields such as agriculture and pharmaceuticals.
The pH meter can be used in fields such as agriculture and pharmaceuticals.
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Hydrogen ions [H+] and bicarbonate ions [HCO -] are both involved in maintaining the acid-base balance in the organism.
Hydrogen ions [H+] and bicarbonate ions [HCO -] are both involved in maintaining the acid-base balance in the organism.
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The pH electrode consists of two different electrodes combined into one probe.
The pH electrode consists of two different electrodes combined into one probe.
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A pH meter measures the concentration of sodium ions [Na+] in a solution as its primary function.
A pH meter measures the concentration of sodium ions [Na+] in a solution as its primary function.
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The interior of the pH probe is filled with a solution of saturated calcium chloride (CaCl2).
The interior of the pH probe is filled with a solution of saturated calcium chloride (CaCl2).
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The pH electrode can function correctly only when in contact with a single type of ion.
The pH electrode can function correctly only when in contact with a single type of ion.
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The kidneys play a significant role in maintaining the acid-base ratio in the body.
The kidneys play a significant role in maintaining the acid-base ratio in the body.
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Study Notes
pH Meter: Purpose and Operation
- Used in various scientific fields, including agriculture, water treatment, petrochemicals, and food science.
- Used in health labs to control culture media and measure broth/buffer acidity.
- Also used for measuring pH in blood components to evaluate patient health.
- Normal plasma pH is between 7.35 and 7.45.
- Measurements relate to patient metabolism, where acids and bases are balanced.
- Acidity/basicity balanced by liberating hydrogen ions (H+) and bicarbonate ions (HCO3-).
- Kidneys maintain acid-base ratio.
- Plasma pH varies with factors such as age and health.
pH Meter: Components
-
Body: Contains circuits, controls, connectors, and display screens.
- ON/OFF switch (some models have cord connection instead)
- Temperature control
- Calibration controls (1 or 2, sometimes 3)
-
Mode Selector:
- Standby (electrode protection)
- pH mode (measurement)
- Millivolt mode (measuring voltage)
- ATC (Automatic Temperature Compensation)
pH Meter: Combined Electrode/Probe
- Integrated reference and internal glass electrode.
- Lower part of probe ends in a round glass bulb (internal electrode).
- Contains saturated KCl and 0.1 M HCl solution.
- Reference electrode cathode inside, and anodized end outside.
- Reference solution in both internal and external tubes.
- Outer tube interacts with solution via porous cap (saline bridge).
- Cannot lose ions due to interactions with surrounding environment during measurements.
pH Meter: Operation Principles
- Measures hydrogen ion concentration ([H+]) using an ion-sensitive electrode.
- Ideal electrode responds solely to one ion type.
- Actual solution often has multiple ions, leading to interactions/interferences.
- External tube must be filled with KCl solution periodically to prevent loss of ions and evaporation.
pH Meter: Calibration
- One Point Calibration: For normal use, with one known pH reference solution
-
Two Point Calibration: For more precise measurements, using two known pH reference solutions.
- Used if instrument isn't used regularly and regular maintenance is lacking
pH Meter: Measuring pH of a Solution
- Remove electrode from calibration solution.
- Rinse and dry the electrode.
- Submerge in the unknown pH solution.
- Turn functions selector to pH mode.
- Read pH on meter.
- Turn functions selector back to standby mode.
- Repeat steps if measuring multiple solutions. Rinse with distilled and dry with lint-free paper in between readings.
pH Meter: Electrode Maintenance
- Frequency: Every four months.
- Steps: Remove electrode from buffer, rinse with distilled water, remove upper cover, fill conduit with saturated KCl solution using syringe, close electrode and cover, rinse in distilled water, store in buffer solution.
pH Meter: Body Maintenance
- Frequency: Every six months.
- Steps: Inspect exterior, check connections, ensure controls are functioning, disconnect, adjust to zero. Ensure indicator(bulb/diode) operates normally
- Other precautions: avoid striking the electrode.
pH Meter: Troubleshooting Table
- Troubleshooting table provided with causes and troubleshooting steps for various problems.
- Example issues and probable causes include: unstable readings, slow response, error messages, no signal, and flashing battery indicator.
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Description
This quiz covers the purpose and components of pH meters used in various scientific fields. Learn how pH meters function in health labs, agriculture, and water treatment, as well as the importance of plasma pH in patient health. Test your knowledge on the different modes and measurements of pH meters.
