describe the change in conductivity as the concentration of the NaCl solution was mathematical relationship does there appear to be between conductivity and. Is there any mathematical formula that can be used to correlate both? The conductivity of a solution depends on the concentration of ALL the ions present, greater the conductivity, These ions all have the electrical unit charges shown by I don't think, at my personal level, that a relationships between conductivity and. Calculate initial concentrations of both [Fe3+] and [SCN-] for each trial. .. the mathematical relationship that exists between concentration and conductivity.Conductivity and Concentration
Electrostatic interactions, which simply refers to the attractive forces between the oppositely charged metal and nonmetal, hold ionic compounds together as solids. Ionic Compounds in Water Some ionic compounds are water-soluble, which means they dissolve in water. When these compounds dissolve, they dissociate, or break into their respective ions. Table salt, also called sodium chloride and abbreviated NaCl, dissociates into sodium Na ions and chloride Cl ions.
Not every ionic compound dissolves in water. Solubility guidelines provide chemists and students a general understanding of which compounds will dissolve and which compounds will not dissolve. Sciencing Video Vault Concentration of a Substance In basic terms, concentration simply refers to the amount of substance dissolved in a given amount of water. Scientists use various units for specifying concentration, such as molarity, normality, mass percent and parts per million.
The exact unit of concentration runs secondary, however, to the general principle that higher concentration means a larger quantity of dissolved salt per unit volume. Electrical Conductivity Many people are surprised to learn that pure water is actually a poor conductor of electricity. Good conductors allow for the easy, sustained flow of electric current. In general, a good conductor possesses charged particles that are relatively mobile free to move. In the case of salts dissolved in water, the ions represent charged particles with relatively high mobility.
However, there exist simple methods that can also be used to reach a similar answers such as using density tables and conductivity of known compounds. Density is defined by the following equation: An important factor to note, as mentioned, about density is that it is not independent to temperature.
Volume of a substance increases as temperature increases due to thermal expansion but the mass remains constant, therefore, at a higher temperature the density of a substance is smaller. Due to this relationship, it is important to take note of the temperature of a compound when measuring its density. Density is a physical property that is unique to every salt and thus compounds can accurately be specified from their density measurements. All compounds have a different solitary mass for a standard volume of 1ml.
Any change in the chemical composition or physical environment affects the density obtained. Hence, when a solution of the unknown salt is used, we have to take into account the ratio of the volume of compound to distilled water that comprises the solution.
This is the concentration of the solution. Then a calibration curve has to be applied since there would exist a range of values of density corresponding to the different concentrations. Where m is the mass, m.
Therefore, a density-concentration graph would be able to give us a straight-line graph with the gradient representing the molar mass of the compound. Here, the composition of the unknown compound can be found by inserting the data obtained of the density and the concentration into the different calibration curves and performing a comparison of its deviation from the straight line graph.
A pycnometer is a device that is used to accurately measure the density of a solution.
A pycnometer is a small metal cylinder with a close-fitting metal stopper that has a capillary hole through it. It holds a specific amount of liquid so any excess liquid is expelled through this hole. A pycnometer also has a cylindrical component that binds the cap and the body of the pycnometer together. To measure the density of a compound, the pycnometer is first filled with distilled water because its density is known and its volume can be found with the following equation: Since the volume of the pycnometer is always constant, the following equation can be obtained: Once density is known, the density-concentration graph can be plotted and by performing linear interpolation: Conductivity is a measure of the number of free moving ions in a solution.
Conductivity Vs. Concentration | Sciencing
The more concentrated a solution is, the more conducting ions the solution will have and thus the solution will have a higher conductivity. Therefore, conductivity should be in a direct linear relationship with concentration.
The following equation represents this relationship: Once the composition of the compound is known, the conductivity of the unknown solution can be compared to that of three other solutions of the same salt but of different concentrations. By linear interpolation in a conductivity-concentration graph, the specific concentration of the unknown solution can be found. Solutions of different concentrations can be obtained through dilution of a standard solution that was prepared. A set amount of mass of salt is first measured using an electronic balance and used to create a mL solution in a volumetric flask.
What kind of mathematical relationship exists between conductivity and concentration
This would act as the standard solution with the concentration calculated using the formula: A second solution of the same composition but different concentration can then be obtained using dilution.
A fixed amount of the standard solution is extracted using a pipette; for higher accuracy and added to a new and clean volumetric flask before filling up the flask with distilled water to form a new diluted solution of volume mL. The theory used in dilution is that the number of moles in the extracted volume of the standard solution is the same as new solution formed.
Therefore, as a fixed amount of volume is extracted from the standard solution, a fraction of the moles of the standard is being transferred into the new solution.
When the solution is made into a mL solution by adding distilled water, the number of moles in the flask is retained but a decrease in concentration is observed due to the increase in volume. Hence, since the number of moles remains the same in both solutions but the volume increases, concentration decreases.
This relationship can be shown by the following equation: The relationship between concentration and conductivity can then be found by measuring the conductivity of these solutions. A conductivity meter is used for the accurate measurement of conductivity.
Approximately 5mL of the solution would be poured out into a smaller cup and its conductivity is measured. Since the 5mL solution is taken to represent the conductivity of the entire solution, extra care has to be taken to ensure that the solution was swirled thoroughly.
Also, the metal rods on the conductivity meter that takes the measurements have to be cleaned and dried properly. Contamination of the rod will lead to errors in the reading of conductivity while excess distilled water left on the rods after drying may dilute the solution and would defeat the purpose of the experiment.
With the results obtained, a conductivity-concentration curve can be constructed and linear interpolation can be carried out to find the conductivity of the unknown solution. This acts as the standard solution for the salt.
Repeat this two more times until there is 30mL of standard solution in the flask. This is the first dilution needed of the standard salt solution.