Mystery Powder SE Conroy Science Work PDF

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Name:

Derrian Stanford

Date:

September 15th 2021

Student Exploration: Mystery Powder Analysis Vocabulary: Biuret solution, iodine solution, litmus paper, vinegar Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Prior Knowledge Questions (Do these BEFORE using the Gizmo.) A white powder is found spilled on the kitchen floor of a crime scene. A similar powder is found on the shoes of a suspect in the crime. 1. What are some powders that you might find on the kitchen floor? Salt, sugar, flour, baking soda. 2. How could you tell if the powder was salt, sugar, flour, or baking soda? If you had no other way of testing them, you could go by taste. Gizmo Warm-up The Mystery Powder Analysis Gizmo allows you to use a variety of tests to identify unknown substances. To start, drag the Baking soda test tube into the “Place tube here” area. 1. Under Appearance, click Test. Is baking soda a fine powder (no visible grains), or is it coarse (visible grains)? It is a powder with no visible grains. 2. Litmus paper is an indicator of acids and bases. Under the Litmus test, click Test. Which of the following results occurred? (highlight the answer.) A. Both strips red (acid)

C. One red, one blue strip (neutral)

B. Both strips blue (base) Both strips were blue 3. Some substances react with vinegar to produce carbon dioxide, visible as bubbles. Under Vinegar test, click Test. Does the vinegar bubble?

Yes

4. The blue Biuret solution turns bright purple in the presence of proteins. Iodine solution turns dark purple in the presence of starch. Try each of these tests. Does baking soda contain protein?

No

Does baking soda contain starch?

No

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Activity A:

Get the Gizmo ready:

Known substances

● Click Reset. ● Be sure the Known substances are selected.

Question: What are the properties of baking powder, baking soda, corn starch, gelatin, and salt? 1. Collect data: Use the Gizmo to test the five known substances. Fill in the results below. Appearance (coarse or fine?)

Substance Baking powder Baking Soda Corn Starch Gelatin Salt

Fine Fine Fine Coarse Coarse

Litmus (acid or base?) Neutral Base Neutral Acid Neutral

Vinegar (bubbles?)

Biuret (protein?)

Iodine (starch?)

Yes Yes No No No

No No No Yes No

Yes No Yes No No

2. Analyze: Look at the results of your tests. A.

Which substance(s) are acids?

Gelatin

B.

Which substance(s) are bases?

Baking Powder, Baking Soda

C.

Which substance(s) react with vinegar?

Baking Powder, Baking Soda.

D.

Which substance(s) contain protein?

Gelatin

E.

Which substance(s) contain starch?

Corn Starch

3. Apply: Suppose you find a mystery powder. It is coarse in appearance, has a neutral pH, and does not react with vinegar, Biuret solution, or iodine. Of the five substances listed here, which is it most likely to be? Salt 4. Challenge: Baking powder is a combination of three substances. One is an acid salt, and the other two are other “known” substances in the Gizmo. What are these two substances? Baking Soda and Cornstarch

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Get the Gizmo ready: Activity B: Unknown substances

● Click Reset. ● Under Select a sample, choose Unknown. ● Check that the Standard mystery set is displayed. (If not, click Refresh or Reload on your browser.)

Question: How can you identify unknown substances? 1. Identify: Test tubes 1-5 all contain single substances. Run the five tests on these powders, and identify the substance in each tube. Sample

Appearance

1

Fine

2

Litmus

Vinegar

Biuret

Iodine

Substance

Neutral

No

No

Yes

Cornstarch

Fine

Base

Yes

No

No

Baking Soda

3

Coarse

Neutral

No

No

No

Salt

4

Fine

Neutral

Yes

No

Yes

Baking powder

5

Coarse

Acid

No

Yes

No

Gelatin

2. Identify: Test tubes 6-10 all contain mixtures of two substances. Run the five tests on these powders, and identify the TWO substances in each tube. Sample

Appearance

Litmus

Vinegar

Biuret

Iodine

Substances

6

Coarse/fine

Acid

No

Yes/no

Yes

7

Coarse/fine

Neutral

Yes

Yes/no

No

Gelatin and cornstarch Salt and baking soda

8

Coarse/fine

Neutral

Yes

No

Yes

Salt and baking powder

9

Fine

Base

Yes

No

Yes

Baking soda and cornstarch

10

Coarse/fine

Acid

Yes

Yes/no

Yes

Gelatin and baking powder

3. Analyze: In the two-substance mixtures you have investigated so far, are there any situations where there is more than one correct answer? Explain. Number nine could be baking soda mixed with either baking powder or cornstarch. They are both fine and have starch present and no protein. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

4. Challenge: Test tubes 11-15 all contain mixtures of three substances. Run the five tests on these powders, and identify the THREE substances in each tube. (Note: Sometimes there will be more than one possible answer.) Sample

11

Appearance

Coarse/fine

Litmus

Acid

Vinegar

Yes

Biuret

Yes/no

Iodine

Substances

Yes

Gelatin, baking powder and baking soda

12

Coarse/fine

Acid

Yes

Yes/no

Yes

13

Coarse/fine

Neutral

Yes

No

Yes

14

Fine

Base

Yes

No

Yes

15

Coarse/fine

Acid

No

Yes/no

Yes

Gelatin, baking powder and cornstarch

Salt,baking powder and cornstarch Baking powder, baking soda and cornstarch

Gelatin, cornstarch and salt

5. Analyze: Based on your experiences, answer the following. A. Why is it hard to tell if a mixture contains salt? Salt is neutral and doesn’t have protein, starch or react with vinegar, so there is nothing that really stands out to identify it. B. How can you tell if a sample contains baking soda and cornstarch or baking powder? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved

All three are fine whereas gelatin and salt are coarse. 6. On your own: For further practice, click New sample. In this set, the contents of every tube is randomized. You may even find new substances you haven’t seen before. Record your observations and make hypotheses about the contents of each tube. Good luck! Not sure what I’m supposed to do for this one. I couldn’t find the new sample.

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