The Unknown Substance

By Garrett Boyce

In order to do this lab, we placed each substance in the indicated boxes. After we put one substance in each of its indicated boxes, we tested what happened when we put different liquids on it. Each substance reacted differently with the varying liquids. The liquids were water, vinegar, iodine, and an indicator liquid. The substances were baking powder, flour, baking soda, cornstarch and an unknown substance. The unknown substance and the baking powder reacted the same way to each liquid.

Who did it?

A forensics lab

Yesterday at 3 AM, at Mike's Awesome Bakery in Francestown, NH the baker arrived to find his assistant baker dead: lying in a pool of blood.  The victim's body was covered in a white powder.  

In an attempt to find the source of the white powder, investigators collect multiple samples from the bakery (baking soda, flour, baking powder, powdered milk, cornstarch).

Investigators are in the process of interviewing employees of the bakery to narrow their field of suspects.  They are also gathering clothing samples from employees to find a match for the white powder.

The investigators need your help.  They need you to write a lab procedure to help them identify the powder covering the body.

MATERIALS AT YOUR DISPOSAL

- baking soda

- baking powder

- flour

- cornstarch

- vinegar

- iodine solution

- universal indicator

- water

- lab materials (beakers, stirrers, pipettes, etc.)

Objective:

Procedure: detailed step by step:

1- Acquire materials listed above

2- In the boxes on the sheet, put a substance in its row vertically

3- Apply liquid based on indicators to the left of the box which the substance should be
   in

4- Record results on separate piece of paper

5- Repeat steps 1-4 until all substances and liquids are used

Analysis: (complete attached data table)

Test solutions	Baking Soda	Baking Powder	Flour	Cornstarch	Unknown
Water	Absorbed immediately, slightly solidified. Physical	Fizzed slightly. Chemical	No reaction. Physical	Sunk in. Physical	Fizzed slightly. Chemical
Vinegar	Substance foamed. Chemical	Fizzed. Chemical	No reaction. Physical	Absorbed slowly. Physical	Fizzed. Chemical
Iodine	Became gelatinous. Physical	Fizzed slightly then turned purple. Chemical	Turned purple then absorbed. Physical	Sat on top, turned purple. Physical	Turned purple, fizzed. Chemical
Indicator	Turned dark blue. Chemical	Turned orange, absorbed. Physical	Turned red and gelatinous. Physical	Turned orange, absorbed slowly. Physical	Turned orange, absorbed. Physical

Conclusion:

What powder should the investigators be looking for when they examine the suspects clothing.  How do you know?  How confident are you in your results and why.

The investigators should look for baking powder. The unknown substance matched the texture and reaction of baking powder exactly. I am very confident in my results. Each test proved to be the same in each way when tested on the unknown substance and baking powder.