Chemistry XXI Units 1 and 2 How do we perform chemical analysis? Midterm Evaluation

Chemistry XXI Lab Session 8 What have you learned?

Chemistry XXI WRITTEN TEST There is not enough room to answer the questions on the test paper. Please answer on separate sheets making sure you identify where each problem is answered. For numerical answers, put a box around the answer. You have one hour. Let’s Start

Chemistry XXI Lab Practical For the second part of the examination, you will go into the lab and perform the experiment individually. After having collected data you will complete and submit your report. You will have two hours.

Chemistry XXI Your Challenge Sherlock Holmes needs your help. A visiting diplomat has been discovered dead in his hotel room along with a cryptic suicide note. Holmes does not believe the note was written by the deceased and wishes to prove so by showing that the ink used in the note does not match any of the pens found in the house. Your assignment is to devise a method to characterize ink components.

Chemistry XXI Initial Ideas and Predictions What is ink made of? Why can we expect to find more than one pigment in black ink? How could we separate and characterize these different pigments? Make a prediction of the number and types of different pigments you expect to separate. Make and sketch of their expected absorption spectra.

Chemistry XXI Separation In this experiment you will use column chromatography (CC) as a separation technique. How are TLC and CC similar or different? Let’s see how to do it.

Chemistry XXI Your Challenge Separate and characterize the different pigments in an ink sample. You have 2 hours Available resources:  Ink sample;  Spectrometer;  Glassware;  Hexane and ethanol.

Chemistry XXI  Beginning questions (2 p): What questions guided your explorations?  Safety Considerations (2 p): What did you do to stay safe in the lab?  Procedures and Tests (2 p): What experiments did you do to answer your questions?  Data, calculations, and representations (6 p): What observations did you make? What data did you collect? What calculations and representations helped you make sense of the data? Your Report

Chemistry XXI  Claims (2 p): What can you claim to answer your questions?  Evidence and Analysis (6 p): How did you interpret your results to support your claims?  Reflections and additional questions (10 p): What did you learn? What do you not completely understand? How have your ideas changed as a result of this lab? What new questions do you have? How would you improve what you did? Your Report