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Increased Conductivity – Worksheet 2

Conductivity in the Lab

Group Names: ________________________________________________

Date: _______________________

Knowledge Base
In this activity you will determine the relationship between conductivity and concentration of sodium chloride (salt, NaCl). Conductivity measures the ability of an aqueous solution to conduct electricity and is determined by the presence of electrolytes (sodium chloride in this experiment). As the salt concentration increases, conductivity increases.

Data Collection

 Drops of 1M NaCl Concentration Conductivity Comparison of Conductivity to NaCl Concentration 0 0.0 mM NaCl 1 0.5 mM 2 1.0 mM 3 1.5 mM 4 2.0 mM 5 2.5 mM 6 3.0 mM 7 3.5 mM 8 4.0 mM 9 4.5 mM 10 5.0 mM

Data Management and Analysis

1. Plot the data, with concentration as the independent variable and conductivity as the dependent variable. Find the regression (best fit) line for the data and write the equation for the best fit line:

2. Rewrite the equation for the line in the following form:

Conductivity = __________________ (Concentration) + _________________

3. Plot the regression line on top of the data.

Interpretation of Results

1. Describe the line formed by your data points. How straight is it?

2. What are outliers? Are there many outliers in your data set? Why?

3. How could you improve the "fit" of your data points?

4. Use the standard curve or regression equation to determine the conductivity of water with a salt concentration of:

 Salt Conductivity 1.25 mM 1.87 mM 2.67 mM 4.21 mM 5.50 mM

Reporting Results

1. How do your results compare with those of other teams? Why might they be different?

2. What sources of error could have been introduced to cause your results to differ from those found by other teams?