flinnsci.com 177
pH Meters, continued
Understanding pH
The pH scale represents the acidity or alkalinity of an aqueous solution. pH is defined as
the negative logarithm of the hydrogen ion concentration of a solution. pH = –logH+.
Absolutely pure water is the standard used in determining pH value. Since the pH scale
is derived from the chemical properties of water, the scale cannot be used with nonaqueous
solutions. The pH scale was established with a range of 0 to 14 pH units. The
low end of the scale is acid, the high end alkaline, with pH 7.00 at the midpoint as neutral.
Each unit on the pH scale represents a tenfold difference in acidity level. For example,
pH 4 is ten times as acidic as pH 5. A pH 3 solution has ten times the acidity level of a
pH 4 solution and 100 times the acidity level of a pH 5 solution.
APPARATUS pH METERS
Phosphorescent Materials
Properly Store and Maintain pH Electrodes
• Most slow, unresponsive pH meters can be rejuvenated by simply soaking the electrode
bulb in a saturated solution of KCl for 30 minutes.
• Gel-filled combination electrodes should be stored in a pH 4 buffer solution with a few
drops of saturated potassium chloride. This slightly acidic solution allows the electrode to
respond faster. Do not use distilled or deionized water; the low ionic strength extracts ions
from the electrode bulb, causing a slower response. Tap water may be used for short-term
storage.
• Use and store electrodes in a vertical position.
• Between samples, rinse electrodes with distilled or deionized water.
• Never wipe the end of an electrode. Dry it by blotting with a lint-free paper like Kimwipes®.
• To prevent breakage during use, always use an electrode swing arm or holder to assist in
raising and lowering the electrode into solutions.
• An electrode rack will help prevent electrode breakage during storage.
See free video at flinnsci.com.
Advanced pH Meter Kit, Benchtop, Orion Star™
The benchtop design is durable, easy-to-operate and gives stable and accurate pH
readings—perfect for students.
• Large LCD displays pH or mV reading and temperature
• Splash-proof exterior and wall-mountable
• Automatic or manual pH calibration
• Three-point calibration with auto-buffer recognition
• Storage memory for 50 data points
• Range: –2.00 to 16.00 pH, –5 to 105 ºC
• Resolution: 0.1, 0.01 pH; 0.1 ºC • Accuracy: ±0.01 pH; ±0.1 ºC
Instrument comes complete with pH meter; combination pH/temperature ATC
refillable electrode; electrode arm and holder; universal power adapter; solution kit
containing 60 mL each of electrode storage, refill, and cleaning solutions; and pH
4, 7 and 10 buffers. Includes instructions and CD with detailed manual and troubleshooting
guide. Accepts any pH probe with a standard BNC connector. Also able to
operate on 4 AA batteries, available separately. 3-year warranty.
Catalog No. Description Price/Each
AP7633 Advanced pH Meter Kit, Benchtop, Orion Star™ $910.00
pH Meter Accessories
Flinn Benchtop Touchscreen pH Meter
Measuring pH and temperature has never been easier
than with this fully digital benchtop pH meter. A large LCD
touchscreen provides easy-to-read pH and temperature
data and can be operated with touchscreen buttons. Unit
is self calibrating, and performs experimental calculations.
The USB interface allows for use
with a computer. Includes pH meter,
pH combined electrode, temperature
electrode, electrode holder, pH standard
buffer solution, 12 V power adapter and
instruction manual.
• Measuring ranges: -2.00–19.99 pH range, -1999–1999 mV, -5.0–105.0 °C
• Resolution: pH: 0.01–0.001, Temperature: 0.01 °C
• Accuracy: pH: ±0.002, 0.1 mV–1 mV, ±0.2 °C
• Automatic and manual temperature compensation
• Able to store up to 200 data sets (printed and deleted)
• 5 calibration points
• Standard RS-232 and USB interface
• Dimensions (mm): 215 x 170 x 35
Catalog No. Description Price/Each
AP9702 Flinn Benchtop Touchscreen pH Meter $660.00
pH Meter Accessories
See details at flinnsci.com.
Catalog No. Description Price/Each
AP1300 Buffer Set for pH Meter Calibration $ 32.00
AP7526 Electrode Rack 52.85
AP8692 Electrode Swing Arm 111.00
AP1391 pH Combination Electrode Replacement 89.70
AP1296 Electrolyte Solution, Saturated 6.55
Low Ion pH Test Kit
High-quality water may not have enough ions to provide
a reliable pH value. If you use standard pH indicator
paper, the indicator in the test paper may be the only
contaminant present when you dip it in the water,
resulting in an erroneous pH value. This low ion test kit
provides you with a sample tube, special low ion test
paper (roll of 25 feet) and a color comparison chart.
Unlike most test paper, this paper is not to be dipped.
Place the paper in the sample tube and add your unknown liquid. Cap the tube and
shake, then read the pH value by holding the tube against the color comparison chart.
Catalog No. Description Price/Each
AP1660 Low Ion pH Test Kit $13.90
Phosphorescent Vinyl Sheet
Glow-in-the-dark vinyl sheet gives off a yellow-green
glow upon absorption of light. Simply place an object,
such as your hand, on the vinyl sheet and expose it to
light. Turn off the lights, and remove your hand from the
sheet. The area where your hand was will remain dark
while the region of the sheet that was exposed to light
will phosphoresce, or glow in the dark! In a darkened
room, exposure to a camera flash will provide the same glow. Great for demonstrating
the principles of absorption and emission of light, particularly the process of phosphorescence.
Material has an adhesive backing and can be easily cut with scissors.
Each sheet is 12" x 12".
Use different color LED micro lights with the phosphorescent vinyl sheet to
demonstrate the effect of wavelength on light energy and phosphorescence! For
free activity instructions, please contact Flinn Scientific and request Publication No.
10978, Phosphorescence and LED Lights.
Catalog No. Description Price/Each
AP4794 Phosphorescent Vinyl Sheet $23.00
AP7784 LED Micro Light, Yellow 12.90
AP7781 LED Micro Light, Blue 12.65
Pins, Push See page 135.
/flinnsci.com
/flinnsci.com
/flinnsci.com
/
/
/
/
/
/
/
/
/
/
/