Conductivity of Ions in Solution

 

 I. Calibration – please refer to the Calibration of Probes document at the end of this section for instructions

 

II.  Taking  Conductivity Readings :

 

If the CBL and calculator have shut off, pressing the ON button on each should take you to where you were after calibration. Be careful that the link cable between the calculator and CBL are not disconnected during the data taking process.

 

1.       

Press PRGM, choose CHEMBIO, press ENTER twice.

Choose 2:COLLECT DATA

 

 

 

2. Select 1:MONITOR INPUT.  Press ENTER.

 

3. Remove the conductivity probe from the distilled water.

 

4. Place the bottom third of the conductivity probe in the 0.01 M  C12H22O11 solution. Record the conductivity

    reading from the calculator in the Data Table. Rinse probe with distilled water.

 

5. Repeat Step 4 for the remaining solutions.

 

6. Place the conductivity probe back in the distilled water.

 

7. To Quit,  press  +  on the calculator. Press QUIT from the Main Menu. Turn off the calculator and CBL.

 

III. Data Analysis

1. Write an equation that shows the ionization of each of the following:

     a)  C12H22O11  Þ

 

     b)  NaCl   Þ

 

     c)  CaCl2   Þ

 

     d)  AlCl3   Þ

 

2. Using the equations in Question 1, determine the number of ions in solution for each

     substance and complete the column Ions in Solution in Data Table 1

 

DATA TABLE 1

Substance

Ions in Solution

Conductivity

C12H22O11

 

 

NaCl

 

 

CaCl2

 

 

AlCl3

 

 

 

3.  What is the relationship between the number of ions in solution and the conductivity of the solution?

 

 

4.Write an equation that shows the ionization of each of the following:

      A)  HC2H3O­2   Þ

      B)  HCl           Þ

      C) NH4OH      Þ

      D)  NaOH        Þ

 

 

                                              Data Table 2

Substance

Ions in solution

predicted conductivity

actual

conductivity

HC2H3O­2

 

 

 

HCl

 

 

 

NH4OH

 

 

 

NaOH

 

 

 

 

1.        Using the equations above determine the number of ions in solution for each substance and complete the column Ions in Solution in Data Table 2.

 

2.         Predict the conductivity for each substance.

 

3.        Were your predictions close to the conductivity actually measured?

 

4.         Explain the differences in the experimental results and your predicted values.