Lab Write up
YOU GAIN 10 POINTS FOR THE LAB WRITE-UP
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Task 1: Do a formal lab write-up. In this experiment, using a pH sensitive litmus paper, we measured how the pH of a basic solution at pH 8.5 (sodium bicarbonate buffer) dropped really low as we were adding a common acid (HCl) . The results are provided in the table below.
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For the ‘introduction: Define the term ‘pH’.
Define the term ‘buffer’. Provide an example of a basic or alkaline fluid of the human body and one for an acidic, vinegar-like fluid that our body has. (2 PTS.)
For the ‘methods’, mention the buffer used. Mention the acid that was added to the buffer and which caused the drop in pH. (2 PTS.)
Task 2: For the ‘Results’, generate a graph from the table below. Take the data and add it to an Excel spreadsheet. Highlight both columns. Go to the menu above and select “Insert,” then click on the icon directly above the word “chart” and select “scatter.” This is the same process as was done in lab 1 for the arm and leg to height ratios. (2 PTS.)
Label the X-axis with drops of HCl and the Y-axis with pH and add a title. (2 PTS.)
Task 3: Provide a ‘summary’ of what the graph shows considering that the y-axis shows pH and pH is dropping. Why does pH decrease? Why is there a plateau at around pH 7 ? Consider what the term buffering means. (1 PTS.)
What does one need to add to increase pH ? (1 PTS.)
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drops HCl added
pH
0
8.5
6
8
9
8
12
8
15
8
18
21
8
24
27
7
30
33
7
36
39
7
42
45
7
48
51
7
54
57
7
60
63
7
66
69
7
72
75
6
78
81
5
84
87
3
90
93
2
96
99
1