Mystery Powder Lab
Title:
Mystery Powder Lab
Objective: “The Objective of the lab is to use my knowledge of ________________
in order to identify _________________________________________.”
Literature Review: On your own – 8 SENTENCE MINIMUM
Hypothesis: “If __________________________, then _______________________.”
Materials: ● Bullet list all materials
Procedures: Summarize in 8 sentences
Data Table: Copy the table that was given to you in your JOURNAL
Analysis Questions: Must copy all questions and answer in complete sentences
Conclusion: 8-12 sentences long
_______________________________________________________________________
Literature Review
pH and litmus paper:
Many common substances are either acids or bases. Some acids, like
stomach acid are necessary for our health, while others, like sulfuric acid are
dangerous and can cause burns and other injuries. Baking soda is a common,
weak base used in our homes, while sodium hydroxide, a strong base, is
hazardous to skin and eyes.
The easiest way to determine if a substance is acidic or basic is to use an
indicator. Indicators are organic molecules that change color in an acid or a
base. When an indicator is placed on paper, it provides a fast way to
determine if a substance has acidic or basic properties. The most common
acid/base indicator paper is called litmus paper, so a litmus test is the first
test used to determine acidic or basic properties. If the litmus paper TURNS
YELLOW, the substance in neutral. IF IT TURNS ORANGE OR RED, the
substance is an acid. IF IT TURNS GREEN OR BLUE, then it is a base.
Biuret test:
A biuret test is used to detect the presence of proteins. A violet color
indicates the presence of proteins. Proteins give a strong biuret reaction
because they contain a large number of peptide bonds. It is possible to use
the biuret reaction to determine the concentration of proteins because (for
most proteins) peptide bonds occur with approximately the same frequency
per gram of material. The biuret test works by the peptides forming a
grouping around a Cu molecule. This grouping has a pink to violet color
depending on the amount of protein.
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Adapted from www.middleschoolscience.com
KECSD – 2011
Mr. Bennett
Iodine test:
An iodine test is used to detect the presence of starch. A dark blue-black
color indicates the presence of starch. This reaction is the result of the
formation of polyiodide chains from the reaction of starch and iodine.
Iodine solution will also react with glycogen, although the color produced is
browner and much less intense.
Vinegar test:
Very simply, vinegar reacts with any carbonate to produce bubbles of CO2.
Procedures:
DO NOT TASTE ANY POWDERS!
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Use your test mat to work on.
Complete all six powders for each test. Each table has one set
of indicator solutions to share between two groups.
Use toothpicks to mix the indicators with the powder. Make sure
to use a new toothpick for each test.
Be sure to rinse and wipe off mat completely before moving onto
the next powder.
Record all results in the data table after each test.
1) Physical properties & pH:
 Add a tiny scoop of mystery powder to the test mat and add 5
drops of water. MIX WELL. Test the pH with litmus paper.
 The litmus paper will turn GREEN OR BLUE in the presence of a
base or ORANGE OR RED in the presence of an acid.
 A YELLOW color indicates a neutral solution.
 Compare the test strip with the pH scale supplied to you.
2) Biuret test:
 Add a tiny scoop of mystery powder to the test mat and 3-5 drops
of water. Mix well.
 Add 3 drops of Biuret A and then 2 drops of Biuret B. MIX
WELL. Wait 30 seconds. If protein is present, IT WILL TURN
PURPLE OR DARK BLUE.
3) Iodine test:
 Add a small scoop of mystery powder to the test mat and 3-5 drops
of water. Mix well.
 Add 2-3 drops of Iodine. MIX WELL. If starch is present, IT
WILL TURN BLACK.
4) Vinegar test:
 Add a small scoop of mystery powder to the test mat
 Add 4 drops of Vinegar. MIX WELL.
 If it fizzes, then GAS HAS BEEN RELEASED.
2
Adapted from www.middleschoolscience.com
KECSD – 2011
Mr. Bennett
Data Table:
Results of Tests on Powders
Test
A
B
C
D
E
F
Crystal / Powder
Observations
Litmus Paper
Acid/Neutral/Base
Biuret Test
Iodine Test
Vinegar Test
Analysis & Results : (COPY QUESTION & answer in Complete Sentences)
1. What did all of the powders have in common?
2. Why is important to use different methods to determine what powder it is?
3. Use the Literature Review information to predict what each compound is.
Conclusion: (8-12 sentence minimum)
1.
2.
3.
4.
3
Restate the Hypothesis and determine if it was correct and why?
Describe the materials and procedures used in the lab.
Explain the data and results.
Were there any mistakes made in the lab?
Adapted from www.middleschoolscience.com
KECSD – 2011
Mr. Bennett