ACTIVITY: SOLUTION CONCENTRATION VS. CONDUCTIVITY Here is your goal for this lesson:

Graph experimental data and interpret results for peer review

A chemistry student carried out an experiment with a conducting apparatus (ammeter) similar to the one below. This ammeter measures in milliamperes (mA). The following data was taken.

Solution Reading

0.1 M H2SO4 150 mA

0.1 M Ba(OH)2 150 mA

To 30 mL of the Ba(OH)2 solution, 10 mL portions of H2SO4 were added until a total of 50 mL of H2SO4 were used. The following results were recorded.

DATA TABLE

Total H2SO4 Added Meter Reading Observations

0 mL 150 mA Ba(OH)2 and H2SO4 clear, colorless

10 mL 65 mA milky white precipitate forms

20 mL 31 mA more precipitate forms

30 mL 0 mA precipitate heavy and settles

40 mL 29 mA no added precipitate seen to form

50 mL 62 mA no change seen

Questions

1. Did you plot the data?

yes

no

2. Did you label your graph axes?

no

yes

3. Did you give your graph a title?

no

yes

4. Does the Ba(OH)2 solution contain ions?

yes

no

5. Does the H2SO4 solution contain ions?

yes

no

6. Explain the data.

Is there any evidence that a reaction has occurred?

7. Does the conductivity increase or decrease?

8. Does the number of ions in solution increase, decrease, or remain constant?

9. What is the indicator of the number of ions in solution?

10. How does this evidence indicate that the reaction has occurred between ions?

11. The Ba(OH)2 dissociates as Ba+2 + 2 OH-. H2SO4 dissociates as 2 H+ + SO4-2.

Write a balanced equation for this reaction.

12. When the conductivity is at a minimum, what must be true about the amount of Ba(OH)2?

13. Why does it not conduct at this low point?

14. Why does it conduct more before and after this minimum point?