Hello, the following is from a standard chemistry course at the university level. It deals with the behavior of electrolytes, in its many varied forms (strong, weak, non), in an aqueous solution. I posted my responses to the questions, not confident about it though.
The student used a conductivity probe to determine the amount of ions in an aqueous solution. Six different calibration points were made.
This is represented by the following link, which displays the graph, and the conductivity values used, below the link. http://i46.tinypic.com/2gui8g3.jpg
k = conductivity, with its units being uS/cm
KCl = Potassium Chloride used as a conductivity standard
Distilled water, k = 0.0 uS/cm**
0.00400 M KCl, k = 578.0 uS/cm**
0.00800 M KCl, k = 1202.6 uS/cm**
0.0200 M KCl, k = 2949.6 uS/cm**
0.0400 M KCl, k = 5560.0 uS/cm**
0.0600 M KCl, k = 8426.9 uS/cm**
**0-10,000 uS/cm setting
--Looking at the conductivity probe calibration curve in the graph, what is the relationship between conductivity and the concentration of a strong electrolyte?
Based on the graph, it seems that the greater the concentration of a solution, the less diluted it is, would in effect, yield a higher value of conduction, representing a greater number of ions present in the solution. Since KCl is used, and it is a strong electrolyte like NaCl, I’m going to assume that 0.02000 M NaCl would yield a similar value as 0.0200M KCl above and in the graph. My logic tells me otherwise, with the above statement. "Since KCl is used, and it is a strong electrolyte like NaCl, I’m going to assume that 0.02000 M NaCl would yield a similar value as 0.0200M KCl above and in the graph."
--In comparison, what would a graph of conductivity versus the concentration of a weak electrolyte look like?
If a weak electrolyte were to be used, it would fall somewhere below the line in the graph. But the question for me is, can a weak electrolyte give off a reading that can confuse the person looking over the graph, and come across as being a strong electrolyte? I’m on the outs on how to determine what the electrolyte conductivity would be for a weak electrolyte as opposed to a strong one, especially if a set of unknown solutions were to be given, and charted on a graph. It becomes an issue of where is the point that separates a strong electrolyte from a weak one. Without knowing the substances involved, it generates more confusion on my part. Is it simply by viewing the solution, and seeing the compound fully dissolve into ions?
--What would a graph of conductivity versus the concentration of a non-electrolyte look like?
If tap water or a non-electrolyte, such as, C12
(sucrose), were to be used, it would produce the same value as distilled water, with 0.0 uS/cm. Therefore, the electrolyte conductivity of a non-electrolyte, such as distilled water, will always be 0.0 uS/cm, and never chart beyond this value, staying fixed at (0,0) on the graph.