Buffering of an acid: (Vinegar) Total number of drops of Vinegar Distilled Water
ID: 1017565 • Letter: B
Question
Buffering of an acid: (Vinegar)
Total number of drops of Vinegar
Distilled Water
(pH)
NaHCO3
(pH)
Na2CO3
(pH)
Buffer
(pH)
0 (start)
7.15
8.23
10.94
9.84
2
4.40
8.27
10.87
9.80
4
4.27
8.32
10.86
9.77
6
4.00
8.33
10.85
9.76
Buffering of a base: (Ammonia)
Total number of drops of Ammonia
Distilled Water
(pH)
NaHCO3
(pH)
Na2CO3
(pH)
Buffer
(pH)
0 (Start)
16.60
8.57
11.23
9.79
1
10.68
8.80
11.22
9.85
2
10.65
8.66
11.17
9.85
3
10.71
8.70
11.12
9.86
4
10.89
8.72
11.10
9.86
1-If each trial of this experiment was controlled, what were the controls?
2- which test tube served as a control group?
3-You know that the buffer system was the baking soda and washing soda together. Why did you test these substances individually ?
4-When you tested the baking soda and washing soda individually, did either of them work alone as a buffer? Explain why you would or would not use empirical (experimental) evidence in your response.
5- The acid you used was vinegar, and the base you used was ammonia. Which substance caused a greater change in the pH of each system, and why do you think this is so? (Keep in mind that the pH of pure vinegar is about three and pure ammonia is about 12).
Total number of drops of Vinegar
Distilled Water
(pH)
NaHCO3
(pH)
Na2CO3
(pH)
Buffer
(pH)
0 (start)
7.15
8.23
10.94
9.84
2
4.40
8.27
10.87
9.80
4
4.27
8.32
10.86
9.77
6
4.00
8.33
10.85
9.76
Explanation / Answer
1- The control experiments in each set are, run with no vinegar and the one with no NH3 in buffer solution. (first entry from each table)
2- First test tube in each table is control experiment.
3- The substances were tested individually so to have pH data when all of acid component or base component is neutralized in buffer by addition of base or acid to the solution.
4- No the substnaces when used alone would not work as buffer as only the conjugate base present woud react with H2O to form OH- in solution in both cases.
5- The greatest change in pH was observed in case of addition of vinegar as it is a stronger acid and would affect the concentration of conjugate base of the buffer system more strongly and causes a higher pH change of solution.
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