1. pH ranges and pH of Buffer Solutions
Experiment 24
pH ranges and pH of Buffer Solutions
CHE118

2. In Lab
Work in groups of 2
Part A is different than what is in lab manual; use the sheets from your CHE118 packet.
Part B is written in the lab manual; use the part B report sheets in the lab manual.
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3. Part A
Determine the pH range of each solution by observing the color of solution and type of indicator used for each solution
Consult Table 24.1 on page 316 of the lab manual
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4. Part A For each solution already prepared:
Record the identity of the solution.
Record the color of the solution.
Record the type of indicator used in the solution.
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5. Part A Example
Solution X with methyl red indicator is yellow (this indicates the pH of soln. X is > 6.0)
Solution X with phenolphthalein is colorless (this indicates that the pH of soln. X is < 8.2)
Solution X with phenol red indicator is yellow (this indicates that the pH of soln. X is < 6.6)
**The pH of solution X is > 6.0 but < 6.6
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6. Part B Prepare the original buffer solution as directed.
Measure the pH the original buffer soln. with the pH meter.
Modify original buffer soln. as directed (add the HCl and NaOH as directed)
Measure the pH of each modified buffer solution.
Calculate the expected pH of original buffer soln.
Calculate the expected pH of each modified soln. (adjust moles buffer acid, moles buffer base, volume change)
CHE118