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Finding Acid Amount From Leftover Base 4 questions
Finding Acid Amount From Leftover Base
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A classroom model measures the acid in a rinse sample. It adds a known excess of base. In the model one OH- ion is used for each H+ ion supplied by the sample. A second measurement finds how much OH- remains unused.
| Record | Amount (mol) |
|---|---|
| OH- added | 0.020 |
| OH- left after the test | 0.006 |
Question 1
Which amount represents the OH⁻ that was used during the test?
- 0.006 mol
- 0.014 mol
- 0.020 mol
- 0.026 mol
Question 2
If only the rinse supplies acid, what amount of H⁺ did the rinse supply? Explain using the model.
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A matched blank contains no rinse sample. In the same type of cup it uses 0.002 mol of OH-. The model assumes an acidic residue in each cup always uses this much base.
Question 3
Complete the table to show the OH⁻ used by the cup and by the rinse. Explain how the blank changes the result.
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Question 4
Explain why using the amount of OH⁻ added, without the leftover and blank readings, would overstate the rinse’s acid amount.
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