PASCO PS-2108 - Manual

Model No. PS-2108 Dissolved Oxygen Sensor 3 ® The negatively charged hydroxide ions diffuse to the silver anode. There they combine with silver (Ag) atoms from the silver anode, forming silver oxide and releasing electrons that join the current in the electrode in the following chemical reaction: Th...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 4 ® Equilibrate the Probe in 100% Humidified Air 1. Place about 5 mL (to a height of about 1 cm) of deionized water into a clean soaker bottle. Slip the cap and O-ring of the soaker bottle over the end of the probe. 2. Insert the probe into the soake...

Model No. PS-2108 Dissolved Oxygen Sensor 5 ® your software settings back to mg/L. DataStudio: Click the Setup button on the DataStudio toolbar. Click the % button next to the Calibrate button and select mg/L from the drop-down menu. Note: Calibration is not required for measurements of relative DO ...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 6 ® General Sampling Procedure 1. Immerse the Dissolved Oxygen probe into the test solution until the silver temperature compensation band is submerged. 2. Click the Start button on the DataStudio tool bar or select Monitor Data from the Experiment m...

Model No. PS-2108 Dissolved Oxygen Sensor 7 ® Maintenance Changing the Electrolyte solution The electrolyte solution (probe filling solution) should be periodically replaced and the silver electrode cleaned to maintain optimal performance of the probe. If the probe is not performing optimally, repla...

Model No. PS-2108 Dissolved Oxygen Sensor 9 ® Storage Short-Term Storage (two weeks or less) Store the probe in the plastic storage bag with the tip inserted in the soaker bottle containing about 10 ml of deionized water. Long-Term Storage (more than two weeks) 1. Unscrew and remove the cartridge ho...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 10 ® Theory of Dissolved Oxygen: What is the chemical mechanism by which diatomic oxygen dissolves in water? This is a particularly eloquent description of the mechanism of oxygen solubility in water: [from Water on the Web 1 ] Water, as a polar mole...

Model No. PS-2108 Dissolved Oxygen Sensor 11 ® 1. Water Temperature effects • Gases usually dissolve in liquids in an exothermic process. This expression represents that process: gas + solvent liquid  gas saturated solvent + heat (this will reach an equilibrium) • Le Chatelier's Principle predicts ...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 12 ® 2. Overlying Gas Pressure Effects • Henry's Law states that the solubility of a gas in a liquid is affected by the pressure of the gas above the liquid-gas interface. P=gas pressure (or partial pressure)C=concentration of dissolved gask = Henry’...

Model No. PS-2108 Dissolved Oxygen Sensor 13 ® equilibrium. A famous, naturally occurring case of supersaturation and subsequent gas release (in this case it was dissolved carbon dioxide gas) was the Lake Nyos tragedy, which took place in Cameroon (1986). 4. Salinity. • Salt and other solids dissolv...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 14 ® 5. Surface Area and Mixing/Turbulence • The surface area of the water/gas interface may affect the rate at which gas dissolves into the water, but ultimately, it will not affect the total amount of gas dissolved at static (non-turbulent) equilib...

Model No. PS-2108 Dissolved Oxygen Sensor 15 ® Experiment 1: Introduction to the Operation of the Dissolved O 2 Sensor Purpose The purpose of the experiment is to explore the basic operation of the Dissolved Oxygen Sensor: how to set it up, how to calibrate it, and how to obtain the most accurate me...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 16 ® 6. Click the Start button on the DataStudio toolbar to begin recording data (Data Run #2). 7. Allow the probe to rest undisturbed in the test solution and observe the sensor reading. 8. After the sensor reading stabilizes at the new level, gentl...

Model No. PS-2108 Dissolved Oxygen Sensor 17 ® Experiment 2: Photosynthesis and Oxygen Generation with Aquatic Plants Purpose Explore the change in level of dissolved oxygen in water associated with photosynthesis of aquatic plants. Materials and Equipment Needed • 2-PASPort DO sensors PS-2108 • 2-P...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 18 ® Procedure 1. Perform a test run on the DO sensor(s) to ensure that the membrane is intact. 2. Arrange equipment so that the two large test tubes are nearly full of water. 3. Clamp test tubes in place vertically, with the beaker as a water bath (...

Model No. PS-2108 Dissolved Oxygen Sensor 19 ® Collecting Data 8. Begin collecting data. Allow the system to take in ambient light for 60 seconds, and then cover the entire set up with an opaque cloth, such as a rubberized lab apron. After fifteen minutes, remove the cover and turn on the light. Con...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 20 ® Experiment 3: Effect of Sodium Sulfite on Dissolved O 2 Concentrations Materials and Equipment Needed • Dissolved Oxygen Sensor • PASPort interface or logger • 2 M sodium sulfite (25.2 g Na 2 SO 3 /100 ml) • aquarium pump or large bottle • PASPo...

Model No. PS-2108 Dissolved Oxygen Sensor 21 ® Questions 1. Describe the effect of sodium sulfite on dissolved O 2 concentrations. 2. Discuss some potential environmental effects of untreated effluent from industries or businesses such as paper mills and photo labs that may use sodium sulfite.

PASPort Dissolved Oxygen Sensor Model No. PS-2108 22 ® Experiment 4: Biochemical Oxygen Demand 1 Background Biochemical oxygen demand (BOD) is an important measure of water quality. BOD is a measurement of the quantity of oxygen used by microorganisms in the aerobic oxidation of organic matter. In r...

Model No. PS-2108 Dissolved Oxygen Sensor 23 ® Experiment 5: The Effect Of Respiration On Dissolved O 2 Concentration Purpose The purpose of the experiment is to explore the effect of respiration on dissolved O 2 concentrations. Materials required • Dissolved Oxygen Sensor (PS-2108) • 400 ml deioniz...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 24 ® 8. Stop recording and save the data. Questions 1. What is the evidence that the yeast cells are alive and respiring during the experiment? 2. What happens to the yeast cells when the dissolved O2 concentration reaches zero? (Hint: Look carefully...

Model No. PS-2108 Dissolved Oxygen Sensor 25 ® Appendix A: Copyright and Warranty Information Copyright Notice The PASCO scientific 012-07688D manual is copyrighted and all rights are reserved. However, permission is granted to non-profit educational institutions for reproduction of any part of the ...

PASPort Dissolved Oxygen Sensor Model No. PS-2108 26 ® Appendix B: Specifications, Replacement Parts, Technical Support Specifications • Cathode: platinum • Anode: silver/silver chloride • Response: 98% in 60 seconds • Stability: Better than 2% • Fully temperature compensated: 10 °C - 40 °C • Temper...

Model No. PS-2108 Dissolved Oxygen Sensor 27 ® Appendix C: Tables Table 1: Concentration of dissolved oxygen (mg/L) in water at various temperatures and pressures From R. F. Weiss (1970). Temp ° C, temperature in degrees Celsius; atmospheric pressures from 695-600 millimeters mercury (27.36-23.62 “H...