logger pro spectrometer identifying cations in substances

LOGGER PRO SPECTROMETER IDENTIFYING CATIONS IN SUBSTANCES ANDROID

Do not completely submerge the sensor.Gently swirl the probe, or stir the solution with a stirring bar and stir plate, during data collection.Be sure the electrode surfaces in the elongated cell are completely submerged in the liquid and that there are no bubbles around the electrode surface.Blot the inside and outside of the electrode cell dry to avoid water droplets diluting or contaminating the sample to be tested.Here are some other tips to ensure best data collection practices: See the Calibration section for more information. If your Conductivity Probe is reading differently from the standard solution, you may simply need to calibrate the sensor. When testing a Conductivity Probe, it is best to measure a standard solution because it is easier to determine if the sensor is reading correctly. If the probe was not temperature compensated, you would notice a change in the conductivity reading as temperature changed, even though the actual ion concentration did not change. This means you can calibrate your probe in the lab, and then use these stored calibrations to take readings in colder (or warmer) water in a lake or stream. Readings are automatically referenced to a conductivity value at 25☌ therefore, the Conductivity Probe will give the same conductivity reading in a solution that is at 15☌ as it would if the same solution were warmed to 25☌. Note that the temperature of a solution is being read by a thermistor that extends into the space between the graphite electrodes. The Vernier Conductivity Probe is automatically temperature compensated between temperatures of 5 and 35☌. It also greatly reduces redox products from forming on the relatively inert graphite electrodes. Thus, the solutions that are being measured for conductivity are not fouled. This very important feature of the Conductivity Probe prevents most electrolysis and polarization from occurring at the electrodes. Each cycle of the alternating current, the polarity of the electrodes is reversed, which in turn reverses the direction of ion flow. This current is converted into a voltage.Īlternating current is supplied to prevent the complete ion migration to the two electrodes. The resulting current is proportional to the conductivity of the solution. k c = (1000 µS) X (1.0 cm -1) = 1000 µS/cmĪ potential difference is applied to the two probe electrodes in the Conductivity Probe.For a solution with a conductance value of 1000 µS, the conductivity, C, would be:Ĭ = G Since the Vernier Conductivity Probe also has a cell constant of 1.0 cm -1, its conductivity and conductance have the same numerical value. The conductivity value is found by multiplying conductance and the cell constant. Where d is the distance between the two electrodes, and A is the area of the electrode surface.įor example, the cell in Figure 1 has a cell constant: The cell constant is determined for a probe using the following formula: Where G is the conductance, and kc is the cell constant. Conductivity, C, is found using the following formula: Since the siemens is a very large unit, aqueous samples are commonly measured in microsiemens, or µS.Įven though the Conductivity Probe is measuring conductance, we are often interested in finding conductivity of a solution. When resistance is measured in ohms, conductance is measured using the SI unit, siemens (formerly known as a mho). The Conductivity Probe is actually measuring conductance, defined as the reciprocal of resistance. Therefore, an increasing concentration of ions in the solution will result in higher conductivity values. In solution, the current flows by ion transport. The Vernier Conductivity Probe measures the ability of a solution to conduct an electric current between two electrodes. For more information about conductivity standard solutions, including recipes for preparation, see Specifications

LOGGER PRO SPECTROMETER IDENTIFYING CATIONS IN SUBSTANCES ANDROID

For instructions for Conductivity Probe calibration using Graphical Analysis with an iOS or Android device, see In order to calibrate a Conductivity Probe, or to confirm that a saved calibration is accurate, you should have a supply of conductivity standard solutions that cover the range of the conductivity values you will be measuring.

For instructions for Conductivity Probe calibration using Graphical Analysis with a Chromebook, see.

For instructions for Conductivity Probe calibration using LabQuest App, see.

For instructions for Conductivity Probe calibration using Logger Pro computer software, see.

It is a simple process that takes only a few minutes.

A calibration equation is stored on each probe before they are shipped, which is used as a default by Vernier software.įor the most accurate measurements with this sensor, we recommend calibration. For many experiments, calibrating the Conductivity Probe is not required.

Logger pro spectrometer identifying cations in substances