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Grossmont College Qualitative Analysis Identifying an Unknown Acid Lab Report
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- Title Page
- Objective
- What was the goal of this experiment? What data will you use to accomplished it?
- Introduction
- Define gram molar mass aka equivalent weight.
- Define titration. What is the purpose of a titration experiment?
- What is a primary standard? What was the primary standard in this experiment? (If you didn’t use a primary standard, indicate what it should have been)
- Why were there 2 standard solutions? That is, why wasn’t NaOH(aq) used as a primary standard for titrating the unknown acid? (If you didn’t use a primary standard, then explain why NaOH(aq) probably should not be used as a primary standard.)
- How would melting of a pure sample differ from melting of an impure sample?
- What is Ka? What is pKa? What does a high Ka mean? What does a high pKa mean?
- What is a buffer?
- For a weak acid, under what conditions will pH = pKa?
- Procedure Reference
- What changes were made to the published procedures?
- Results and Calculations
- Use the results that were provided to you and clearly indicate your unknown number.
- Create (don’t copy the Excel tables) a table summarizing your major experimental data (i.e. gram molar mass, melting point, and pKa of monoprotic unknown acid).
- Show sample calculations.
- Make a second summary table that shows the theoretical values for your top 2 or 3 best guesses for the unknown acid’s identity. This table should include the theoretical gram molar mass, melting point, and pKa of these guesses with percent error values.
- Use the results that were provided to you and clearly indicate your unknown number.
- Discussion
- State the identity of your unknown monoprotic acid from a list of possibilities (Links to an external site.) by using
- Remember to be quantitative, whenever possible.
- Discuss how you came to that conclusion using your average gram molar mass with standard deviation and average melting point range and pKa to justify your identification.
- Explain how you narrowed down the suspects and state your second choice and/or third choice, if appropriate and how they were eliminated.
- Be sure the discussion includes, how many standard deviations the actual molar mass of the acid you believe best represents your unknown is away from the experimental molecular mass of the acid.
- Also, does the actual melting point of your identified acid fall within the range of your experimental average melting points? Explain why or why not.
- Discuss the accuracy and precision of your average gram molar mass and melting point. (How do you quantify accuracy? How do you quantify precision?)
- Discuss any sources of error that may have occurred in the experiment. For example, if you added too much base to one of your titrations, you should identify how that would have affected your gram molar mass calculation. Would it increase or decrease?
- State the identity of your unknown monoprotic acid from a list of possibilities (Links to an external site.) by using
- Conclusion
- Evaluate the objective of the experiment and restate the identity of your unknown acid, the average gram molar mass, the average melting point range, and the average pKa.
- Post Lab Questions
