Last modified: Wed 12/31/1969 06:00:00 pm
BCE

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Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.


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In the BCE you will view a series of videos depicting the behavior of a buffer solution. Alka-Seltzer contains several different compounds that have buffer capacity. The compounds are sodium bicarbonate, NaHCO3 and citric acid/sodium citrate, H3C6H5O7. In the series of videos you will see what happens when a strong acid and a strong base are added to water in the presence of a mixture of indicators, and what happens when Alka-Seltzer is added to a solution of a strong acid and a solution of a strong base.

In the first video two indicators are added each of three beakers. The two indicators are bromocresol green and phenolphthalein.

 

1. What color is the the indicator mixture (bromocresol green and phenolphthalein) in water?

In the second video 10 drops of 0.100 M HCl is added to the beaker of indicator solution on the left.

 

2a. What color does the indicator mixture change to after addition of 10 drops of 0.100 M HCl?

2b. What is the pH of a solution of 0.100 M HCl?

pH =

2c. Assuming 10 drops is approximately 0.500 mL, calculate the pH of the solution when 10 drops of 0.100 M HCl is added to 100 mL of water? (assume that adding 10 drops to 100 mLs of water does not change the volume of the new solution.). Calculate the pH of the solution in the beaker on the left.

pH =

In the third video 10 drops of 0.100 M NaOH is added to the beaker of indicator solution on the right.

 

3a. What color does the indicator mixture change to after addition of 10 drops of 0.100 M NaOH?

3b. What is the pH of a solution of 0.100 M NaOH?

mL

3c. Assuming 10 drops is approximately 0.500 mL, calculate the pH of the solution when 10 drops of 0.100 M NaOH is added to 100 mL of water? (assume that adding 10 drops to 100 mLs of water does not change the volume of the new solution.). Calculate the pH of the solution in the beaker on the left.

pH =

In the fourth video half of a tablet of Alka-Seltzer is added to the beaker on the left.

 

4a. What color does the indicator mixture change to after addition of half of a tablet of Alka-Seltzer?

4b. What do you think the pH of the solution in the left beaker is following the addition of half-tablet of Alka-Seltzer?

pH =

In the fifth video half of a tablet of Alka-Seltzer is going to be added to the beaker on the right.

 

5. Predict the color of the indicator mixture in the beaker on the right after addition of half of a tablet of Alka-Seltzer?

In the sixth video half the half tablet of Alka-Seltzer is added to the beaker on the right.

 

6. What do you think the pH of the solution in the right beaker is following the addition of half-tablet of Alka-Seltzer?

pH =

 

Before watching the next video, predict what you think will happen to the color of the indicator in the solution in the beaker on the left, if additional 0.100 M HCl is added.

In the seventh video additional 0.100 M HCl is added to the beaker on the left.

 

7a. What happened to the color of the solution in the beaker on the left after adding more 0.100 M HCl?

Before watching the next video, predict what you think will happen to the color of the indicator in the solution in the beaker on the right, if additional 0.100 M NaOH is added.

In the eighth video additional 0.100 M NaOH is added to the beaker on the right.

 

8a. What happened to the color of the solution in the beaker on the right after adding more 0.100 M NaOH?

9. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

10. If there is one question you would like to have answered in lecture, what would that question be?