Buffering of a acid : (vinegar) Total number of drops ofVinegar Distilled Water
ID: 1017510 • Letter: B
Question
Buffering of a acid : (vinegar)
Total number of drops ofVinegar
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
8
3.91
8.34
10.82
9.74
10
3.80
8.35
10.81
9.73
12
3.76
8.37
10.77
9.72
Buffering of a base: (Ammonia)
Total number of drops of Ammonia
Distilled Water
(pH)
NaHCO3
(pH)
Na2CO3
(pH)
Buffer
(pH)
0 (Start)
16.60
5.57
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
5
10.90
8.74
11.08
8.87
6
10.99
8.75
11.07
9.88
1-The buffer solution you made had nearly equal molar parts of weak acid and conjugate base. If you wanted to use this same buffer system (bicarbonate- carbonate) at a lower pH (more acidic), how would you need to change the proportions of weak acid and conjugate base to lower the pH of the buffer solution?
2- How would you change the proportions of the weak acid and conjugate base to make a buffer solution that is useful at a higher pH (more basic)?
3-What substance in this lab is amphoteric?
4- What empirical evidence do you have that this substance has amphoteric properties?
Total number of drops ofVinegar
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
8
3.91
8.34
10.82
9.74
10
3.80
8.35
10.81
9.73
12
3.76
8.37
10.77
9.72
Explanation / Answer
1- if you use high molar part of NaHCO3 and lower of Na2Co3. you will get the lower acid pH .
2- Reverse of above will give high pH buffer.
3- NaHCO3
4- It can react with both acid and bases.
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