TEKS 5 - CoachGravesAwesomeClass

TEKS
Name ___________________________ Class ________ Date ___________
Chemistry
Lab Investigation 9C, 2I, 3A
TEKS 9C Describe the postulates of kinetic molecular theory.
TEKS 2I Communicate valid conclusions supported by the data through
methods such as lab reports, labeled drawings, graphs, journals, summaries,
oral reports, and technology-based reports. (Also 3A)
Descriptive
Lab 9C, 2I, 3A: Diffusion
Purpose
To infer diffusion of a gas by observing color changes during chemical reactions
Materials
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clear plastic cup or petri dish
reaction surface
dropper bottles containing bromothymol blue, hydrochloric acid, and sodium hydrogen sulfite
ruler
cotton swab
NaOH, NH4Cl (optional)
Safety
Wear safety glasses and follow the standard safety procedures.
Procedure
1. On a sheet of paper, draw the large circle shown in Figure A,
using the plastic cup or petri dish.
2. Place a reaction surface over the grid and add small drops of
bromothymol blue (BTB) in the pattern shown by the small
circles. Make sure the drops do not touch one another.
3. Mix one drop each of hydrochloric acid (HCl) and sodium
hydrogen sulfite (NaHSO3) in the center of the pattern.
4. Place the cup or petri dish over the grid and observe what
happens.
5. If you plan to do Activity 1 in the You’re the Chemist section, don’t dispose of your materials yet.
1
Name ___________________________ Class ________ Date ___________
TEKS
Chemistry
Lab Investigation 9C, 2I, 3A
Analyze and Conclude
1. Observe Describe in detail the changes you observed in the drops of
BTB over time. Draw pictures to illustrate the changes.
Descriptive
2. Describe Draw a series of pictures showing how one of the BTB drops might look over time if you
could view the drop from the side.
3. Communicate Valid Conclusions The BTB changed even though you added nothing to it. If the
mixture in the center circle produced a gas, would this explain the change in the drops of BTB? Use
your drawings to support your conclusion.
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2
Name ___________________________ Class ________ Date ___________
TEKS
Chemistry
Lab Investigation 9C, 2I, 3A
4. Describe Describe the five postulates of kinetic molecular theory. Which
of these postulates explain your observations in this investigation?
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Descriptive
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5. Apply Concepts Translate the following word equation into a balanced chemical equation:
Sodium hydrogen sulfite reacts with hydrochloric acid to produce sulfur dioxide gas, water, and
sodium chloride.
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You’re the Chemist
1. Analyze and Evaluate Scientific Explanations Use a cotton swab to carefully absorb the center
mixture of the original investigation and replace it with one drop of NaOH and one drop of NH4Cl.
Ammonium chloride reacts with sodium hydroxide to produce ammonia gas, water, and sodium
chloride. Write and balance a chemical equation to describe this reaction. Describe what happens
and use your observational testing to analyze and evaluate the postulates of kinetic molecular
theory.
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3
Name ___________________________ Class ________ Date ___________
TEKS
Chemistry
Lab Investigation 9C, 2I, 3A
2. Design an Investigation Design an investigation to observe the effect
of the size of the BTB drops on the rate at which they change. Explain
your results in terms of kinetic molecular theory.
Descriptive
4

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