American Commercial College of Texas Conductivity Lab Report

User Generated

Wrss221

Writing

American Commercial College of Texas

Description

Hello, i'll upload all the pictures. and I will upload how a good lab report should look like.and the last picture is my result in the lab. the last blanks of the table on the right you should calculate the answer by using the formula on the sheets.


make it simple.

Unformatted Attachment Preview

CONDUCTIVITY OBJECT: : The object of this lab is to learn techniques used for measuring conductivity of water. When the lab is completed the student should know: How to adjust a conductivity meter to proper operating conditions What a cell constant is Why conductivity is temperature dependent How to correctly report conductivity in terms of specific conductance What a conductivity standard is How to estimate the amount of dissolved solids in water by use of the conductivity reading How to establish a probe correction factor DISCUSSION: Conductivity is a numerical expression of the ability of water to carry an electric current. The ability of water to carry a current depends on the temperature of the solution as well as the type of ions present and their total concentration, mobility, and valence. Solutions of most inorganic acids, bases and salts are good conductors. Conversely, molecules of organic compounds that do not dissociate in water conduct a current very poorly. Some areas where conductivity plays a significant role are: In establishing the degree of mineralization of water in order to assess its affect on plants and animals, as well as corrosion rates. In evaluating variations in dissolved mineral concentration of raw water and waste water. In determining the quality of distilled or deionized water. Freshly distilled water has a conductivity of 0.5 to 2 microsiemens/cm and increases to 4 microsiemens/cm after a few weeks due to the absorption of atmospheric carbon dioxide. In assessing the effects of salt water intrusion on groundwater supplies In estimating total dissolved solids. The conductivity value can be multiplied by a factor ranging from 0.55 to 0.9 in order to obtain a rough estimate of the total dissolved solids (mg/L). The amount of the factor is dependent on the temperature and soluble components of the water. If unsure of the content of the water, a factor of 0.59 can be used. Conductivity measurements are made in a conductivity cell using an alternating current - Wheatstone bridge electrical setup. In reality, resistance measurements are made and are then converted to conductivity by the conductivity meter. The units for reporting conductivity are microsiemens/cm (uS/cm). It should be noted that in the International System of Units (SI) conductivity is reported as Siemen. The United States is starting to adopt this nomenclature and is in the process of eliminating the use of "mho". For reference one "mho" is equal to one "Siemen". The cell that measures the resistance has platinum or nickel electrodes. Each cell has a cell constant, which is used to establish a conductivity reading. A cell constant (Q) is the ratio of the distance (d) between the electrodes to their area (a), d/a for a given cell. The actual conductivity measurement in seimens is multiplied by the cell constant (cm/cm²) and the result is a conductivity reading of seimens/cm. All meters automatically multiply the measurement by the cell constant and thus the units of measurement for conductivity meters are seimens/cm. This value is known as "Specific Conductivity" (Ksc). Electrolytic conductivity increases with temperature at a rate of 1.9% per °C primarily due to the increased mobility of ions. Significant errors can result from inaccurate temperature measurement. When reporting results it is essential that the affect of the temperature be compensated for and universal units used. For precise work, conductivity should always be determined and reported at the standardized temperature of 25°C. Newer conductivity meters (post 2000) automatically convert the readings to 25°C. Older meters (pre 2000) do not automatically convert the reading to conductivity at 25°C. The older meters give a direct reading, which can be converted to conductivity at 25°C by using the following formula: This should be insone orden K25 = Ksc/[1 + 0.019(t -25)] where: K25 = Conductivity at 25 °C (uS/cm) Ksc = Specific Conductivity read from meter (uS/cm) t = Temperature °C 1 + 0.019 = factors in 1.9% change in conductivity per°C 25 = factors in spec. cond. temperature of 25°C As an alternative to the equation listed above (and much easier method), a table of correction factors may be used to correct the measured conductivity to conductivity at 25°C. A table of correction factors can be found in numerous water sampling books or by using a little math and a lot of patience you can create one. The following equation is used when there is access to a temperature correction factor table: Ksc X TCF = KSC25 where: Ksc = Specific conductivity read from meter (uS/cm) TCF = Temperature correction factor = value taken from correction table. Care must be taken to use the value that corresponds exactly with temperature of sample K25 = Conductivity as uS/cm at 25°C N Conductivity cells tend to change with time as the electrodes become dirty or as the platinum and /or nickel flakes off. To compensate for the changes, either a probe correction factor must be used or the meter should be calibrated. Whichever procedure used depends on the type of meter. Meters purchased prior to 2000 will probably need a probe correction factor. Meters purchased after 2000 will probably need calibration Establishing a probe correction factor is accomplished by comparing the actual conductivity of a standard to the measured conductivity of the standard (both adjusted to 25°C) a probe correction factor is established. (NOTE: A conductivity standard is a solution that has an exact known amount of conductivity. As with other standards, it is used for QA/QC). The following equation shows how to establish a probe correction factor: PCF=K2s standard/K25 measured where: : PCF = probe correction factor K25 standard = conductivity of known value converted to 25°C (uS/cm) K25 measured = conductivity reading from meter converted to 25°C (uS/cm) When a probe correction factor is needed the following equation is used to determine specific conductivity corrected to 25°C: KSC25 = K25 X PCF where: Ksc = Specific Conductivity as uS/cm at 25°C K25 = Conductivity reading from meter CORRECTED TO 25°C (uS/cm) PCF = Probe Correction Factor NOTE: When you use a conductivity meter that is calibrated directly do not include a value for PCF in your calculations. NOTE: Conductivity is always reported in terms of specific conductivity and temperature compensation of 25°C. This allows for ease of communication when comparing samples taken at different temperatures and different cell constants. REFERENCES: 1. Standard Methods 2510: Conductivity (pgs 127-131) 2. Operating Manual for YSI Model 30 S-C-T meter 3 Conductivity measurements are made in a conductivity cell using an alternating current - Wheatstone bridge electrical setup. In reality, resistance measurements are made and are then converted to conductivity by the conductivity meter. The units for reporting conductivity are microsiemens/cm (uS/cm). It should be noted that in the International System of Units (SI) conductivity is reported as Siemen. The United States is starting to adopt this nomenclature and is in the process of eliminating the use of "mho". For reference one "mho" is equal to one "Siemen". The cell that measures the resistance has platinum or nickel electrodes. Each cell has a cell constant, which is used to establish a conductivity reading. A cell constant (Q) is the ratio of the distance (d) between the electrodes to their area (a), d/a for a given cell. The actual conductivity measurement in seimens is multiplied by the cell constant (cm/cm²) and the result is a conductivity reading of seimens/cm. All meters automatically multiply the measurement by the cell constant and thus the units of measurement for conductivity meters are seimens/cm. This value is known as "Specific Conductivity" (Ksc). Electrolytic conductivity increases with temperature at a rate of 1.9% per °C primarily due to the increased mobility of ions. Significant errors can result from inaccurate temperature measurement. When reporting results it is essential that the affect of the temperature be compensated for and universal units used. For precise work, conductivity should always be determined and reported at the standardized temperature of 25°C. Newer conductivity meters (post 2000) automatically convert the readings to 25°C. Older meters (pre 2000) do not automatically convert the reading to conductivity at 25°C. The older meters give a direct reading, which can be converted to conductivity at 25°C by using the following formula: This should be insone orden K25 = Ksc/[1 + 0.019(t -25)] where: K25 = Conductivity at 25 °C (uS/cm) Ksc = Specific Conductivity read from meter (uS/cm) t = Temperature °C 1 + 0.019 = factors in 1.9% change in conductivity per°C 25 = factors in spec. cond. temperature of 25°C As an alternative to the equation listed above (and much easier method), a table of correction factors may be used to correct the measured conductivity to conductivity at 25°C. A table of correction factors can be found in numerous water sampling books or by using a little math and a lot of patience you can create one. The following equation is used when there is access to a temperature correction factor table: Ksc X TCF = KSC25 where: Ksc = Specific conductivity read from meter (uS/cm) TCF = Temperature correction factor = value taken from correction table. Care must be taken to use the value that corresponds exactly with temperature of sample K25 = Conductivity as uS/cm at 25°C N uus) blinking (ر) I-K 25 Ksc (c) como consecte K25 wad 8.32 MS 17.90s 17.aco Casou 1590M 1842 M 17.900 Emergen-C . с C « 95045 1099MC 3.3 NS 2 gais! 17.8 Co 12.10 D.T Water
Purchase answer to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Explanation & Answer

Attached.

Conductivity Lab Report
Object
The object of this lab is to learn techniques used for measuring conductivity of water.
Procedures
Refer to:




standard methods 2510 A: Introduction pg. 127 to 129 and 2510 B: Laboratory
method, pg. 130 to 131.
Operation manual for YSI Model 30 S-C-T meter.
Lab handout

Handling
1. Rinse the probe very well between me...


Anonymous
Nice! Really impressed with the quality.

Studypool
4.7
Trustpilot
4.5
Sitejabber
4.4

Related Tags