QQuestionAnatomy and Physiology
QuestionAnatomy and Physiology
Brand of vinegar or unknown no.
| | | Dish | |
| --- | --- | --- | --- |
| | Trial 1 | Trial 2 | Trial 1 |
| 1. Mass of flask (g) | 40.3016g | 91.0265g | 73.8552g |
| 2. Mass of flask + vinegar (g) | 45.8638g | 94.9985g | 78.5294g |
| 3. Mass of vinegar (g) | 5.5522g | 3.912g | 4.6742g |
| B. Analysis of Vinegar Sample | | | |
| 1. Buret reading of NaOH, initial (mL) | 0 mL | 0.5 mL | 0 mL |
| 2. Buret reading of NaOH, final (mL) | 28 mL | 28 mL | 28.5 mL |
| 3. Volume of NaOH used (mL) | 28 mL | 27.5 mL | 28.5 mL |
| 4. Molar concentration of NaOH (mol/L) | 0.11635 mol/L | | 0.11635 mol/L |
| 5. Moles of NaOH added (mol) | 3.2578 x^10 - 3 mol | 3.199625 x^10 - 3 mol | 3.315975 x^10 - 3 mol |
| 6. Moles of CH₃COOH in vinegar (mol) | 3.2578 x^10 - 3 mol | 3.199625 x^10 - 3 mol | 3.315975 x^10 - 3 mol |
| 7. Mass of CH₃COOH in vinegar (g) | 0.195468g | 0.1919775g | 0.1989585g |
| 8. Percent by mass of CH₃COOH in vinegar (%) | 3.52% | 5% | 4.3% |
| 9. Average percent by mass of CH₃COOH in vinegar (%) | 4.27% | | |
*Calculations for Trial 1 of the first vinegar sample on next page.
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Answer
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Step 1: Calculate the mass of vinegar in Trial 1 of the first vinegar sample.
The mass of the flask with vinegar (m2) is 45.8638 g, and the mass of the empty flask (m1) is 40.3016 g. To find the mass of the vinegar, subtract the mass of the empty flask from the mass of the flask with vinegar: m(2$) = m^2 - m^1 m(2$) = 45.8638 g - 40.3016 g
Step 2: Convert the mass of vinegar to moles.
To convert the mass of vinegar to moles, we need the molar mass of acetic acid (CH^3COOH), which is approximately 60.05 g/mol. Divide the mass of vinegar by the molar mass: n(2$) = m(2$) / M(CH^3COOH) n(2$) = 5.5522 g / 60.05 g/mol n(2$) ≈ 0.09246 mol
Final Answer
The calculated percent by mass of acetic acid in the vinegar is 100%, while the experimental value is 3.52%. The difference suggests an error in the experimental data, most likely in the mass measurements.
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