I need an explanation for this Chemistry question to help me study.

I attached the graphs, my data and the lab manual below ( thats lab 16 in case to find it in the lab manual)

Title page

  • Name, date, experiment number, experiment title


  • Write all objectives of this experiment. Use complete sentences.


  • Include the following in your introduction. Write in complete sentences with developed paragraphs. Organize so there is a logical flow of ideas.
    • What is a colligative property?
    • What is the van’t Hoff i-factor?
    • What is molality?
    • What is the important equation for freezing point depression that you will use to calculate the molar mass of the unknown?
  • Give a brief introduction about how the objectives will be met. This should include a brief description of the experiment and what chemicals will be used.


  • Cite the manual
  • Include any modifications to the procedure. (You will be doing 3 trials instead of 2). You will skip Part II.


  1. Make a graph for each of your runs.
    • You only need to report your 2 best runs for each part (6 graphs total for parts I, II, and III). Graphs from part I should show how you determined the freezing temperature. Graphs from part II and III must show how you determined the final temperature. Make sure the graphs are labeled so that it is clear which graph is which. Give more descriptive titles than “Trial 1, Part 1” or “Part 3, Trial 2” since they require reference to the procedure. The reader should be able to understand what is being shown in the graph by looking at the title, without having to reference the procedure.
    • You can take screen shots of the graphs if you use logger pro. On Windows, you can use the “Snipping Tool” to take a screenshot of the graph.
  2. Organize into a table
  3. For Part II: Calculate the %error of your experimental Kf value (literature value for lauric acid: Kf = 3.90oC/m)
  4. For Part III: Calculate the %error for your Molar mass, assuming your unknown is benzoic acid (C7H6O2).


  • Provide a sample calculation for each type of calculation


  • Analyze the data in your table.
    • Does it make sense; did you get the expected results?
      • Discuss whether the experiment shows evidence of a colligative property
      • Discuss the correlation between molal concentration of unknown and freezing point depression
      • Discuss the calculated %error
    • ****Remember to be quantitative in your analysis*****
  • Discuss sources of error
    • If you have significant error, explain plausible sources of error that explain the error in YOUR experiment.
    • If you had no significant error, discuss general sources of error for this experiment.


  • Restate your major results. Be quantitative.

Postlab Questions

  • Answer the Postlab Questions on the preprinted lab manual sheets.

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