Activity Detail
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Forensics Case 5
The Ink Is Still Wet: Using colorimetry to identify an unknown ink
 


Activity Overview

In this activity, students identify the ink of a ransom note to match suspects. They identify an unknown ink by its light absorbance characteristics. The experiment set up used is to measure a solutions absorbance of different colors (wavelengths) of light.

Before the Activity

  • Use TI Connect™ to download Vernier EasyData™ application
  • Connect the Colorimeter to the: Vernier EasyLink™ interface
  • Plug EasyLink into the USB port of the calculator
  • Set up the calculator and the Colorimeter for data collection
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 44 - 47 from the attached PDF file for the class
  • Print sample data and student work pages

    		•

    		During the Activity

    		Distribute the pages to the class.

    Follow the Activity procedures:
  • Prepare the blank, each of the five standards, and the unknown ink for analysis
  • Calibrate the Colorimeter
  • Collect absorbance-concentration data at 635 nm for the solutions
  • Graph the data
  • Examine the data points along the curve on the displayed graph, and write the absorbance values in your Evidence Record sheet
  • Measure the absorbance of each solution at the three other wavelengths 565 nm, 470 nm, and 430 nm
  • Discard the solutions as directed
  • Identify the unknown sample

    		After the Activity

    		Students analyze the results and answer the Case analysis questions on the Evidence Record sheet.

    Review student results:
  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary

    		Other Downloads




    view standards alignment
    view textbook alignment

    Subject Area:
    Math : Statistics : Data Analysis
    Science : Forensics : Data Analysis

    Author:
    Texas Instruments

    Level:
    9-12

    Activity Time:
    60 minutes

    Device:
    TI-83 Plus Family, TI-84 Plus Family

    Apps:
    EasyData™

    Software:
    TI Connect™

    Accessories:
    Sensor - Colorimeter, TI Connectivity Cable, Unit-to-Unit link cables

    Other:
    This is Activity 5 from the EXPLORATIONS Book:
    Forensics: Connecting Science Investigations with TI Data Collection Activities.

    The following materials are required for this activity:

  • Vernier EasyLink
  • Colorimeter
  • 6 cuvettes
  • Colored wax pencil
  • 5 dropper bottles, with 10 mL samples of 5 different diluted black inks
  • 1 dropper bottle with 10 mL of diluted unknown black ink
  • Deionized or distilled water
  • Lint-free tissues
  • Goggles


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