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MicroScale

History
Using These Materials
Why MicroScale?
Safety
Comments

Absolutely no assurances are made regarding the safety of the classroom activities described herein.

01, Density of Glass Description Experiment
02, Observing Reactions Description Experiment
03, Characteristic Properties Description Experiment
04, Reactions of Copper Description Experiment
05, Viscosity of Liquids Description Experiment
06, Paper Chromatography Description Experiment
07, Precipitation Stoichiometry Description Experiment
08, The Formula of a Compound Description Experiment
09, Forming, Testing, and Modifying Hypotheses Description Experiment
10, Dioxygen Description Experiment
11, Boyle's Law Description Experiment
12, Charles' Law Description Experiment
13, Diffusion in a Tube Description Experiment
14, Diffusion of Two Gases in Two Dimensions Description Experiment
15, The Molar Volume of a Gas Description Experiment
16, Decomposition of Copper Carbonate Description Experiment
17, pH Indicators Description Experiment
18, Titration Strong Acid/Strong Base Description Experiment
19, Titration of Vinegar Description Experiment
20, Ksp for Calcium Hydroxide Description Experiment
21, Puzzle Titration Description Experiment
22, Bronsted/Lowry Acids and Bases Description Experiment
23, Solubility of Ammonia Description Experiment
24, Solution Formation Description Experiment
25, Temperature and Solubility Description Experiment
26, Polar and Nonpolar Solvents Description Experiment
27, Electrical Conductivity Description Experiment
28, Electrolysis Description Experiment
29, Activity Series (Reduction Potential) Description Experiment
30, Voltaic Cells Description Experiment
31, Using Solubility Rules Description Experiment
32, Combining Cations and Anions Description Experiment
33, Copper Ammine Complex Formation Description Experiment
34, Le Chatelier's Principle Description Experiment
35, Six Solutions Description Experiment
36, Qualitative Analysis Description Experiment
37, Iodine Clock Kinetics Description Experiment
38, Kinetic Study of Thiosulfate in Acid Description Experiment
39, Halogen Chemistry Description Experiment
40, Halide Ions Description Experiment
41, Tests for Iron(II) and Iron(III) Ions Description Experiment
42, Silver Mirror Description Experiment
43, Esters Description Experiment

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Descriptions

01, Density of Glass Experiment
The densities of 6 different pieces of glass are measured using a balance and graduated cylinder to demonstrate that the factors of size, shape, and number do not affect density.

02, Observing Reactions Experiment
Two seemingly identical sets of chemicals are provided for student study. Students systematically observe the results of combining the chemicals. When sharing the results with an entire class, debate regarding the differences in observations often ensues.

03, Characteristic Properties Experiment
The students are given a sample of an unknown liquid which they then study to determine its freezing and boiling points.

04, Reactions of Copper Experiment
Copper metal is dissolved in nitric acid. Copper (II) hydroxide is formed by reaction with sodium hydroxide. Copper (II) oxide is formed by heating. Copper (II) oxide is dissolved in acid. Copper (II) ions are reduced with zinc metal.

05, Viscosity of Liquids Experiment
The viscosities of three different liquids are determined by measuring the time required for a set amount of each liquid to drain from a modified Beral pipet. Conclusions about the nature of viscosity are drawn from the results.

06, Paper Chromatography Experiment
The dyes in water soluble inks are separated by paper chromatography to introduce students to the technique.

07, Precipitation Stoichiometry Experiment
Students will determine the approximate combining ratios for reactions of calcium chloride by combining reactants in varying proportions in a 12-well strip and visually determining which well contains the largest amount of precipitate.

08, The Formula of a Compound Experiment
The formula for the precipitate resulting from mixing cobalt chloride and sodium hydroxide is determined by precipitation titration.

09, Forming, Testing, and Modifying Hypotheses Experiment
This is a modification of the "blue bottle" demonstration using small test tubes. The emphasis is on forming and adapting a hypothesis to the information known at the time. It shows that as what you see changes, what you believe to be happening also changes.

10, Dioxygen Experiment
Oxygen is collected from the catalyzed decomposition of hydrogen peroxide and its properties are observed.

11, Boyle's Law Experiment
A setup using a small insulin syringe as a piston is used to determine the relationship between the volume and pressure for a fixed mass of gas at constant temperature.

12, Charles' Law Experiment
This procedure uses the air trapped inside of a Beral pipet at different temperatures to demonstrate Charles' Law. In order to do this, we must assume that a constant pressure is exerted by equal depths of hot and cold water and that that pressure causes no significant distortion of a Beral pipet.

13, Diffusion in a Tube Experiment
The rate of diffusion of two gases is observed by measuring the distance in a tube that a precipitate forms from the source of each gas.

14, Diffusion of Two Gases in Two Dimensions Experiment
The diffusion of two gases across a 96-well plate filled with substances which are sensitive to the presence of these gases is observed.

15, The Molar Volume of a Gas Experiment
The molar volume of the gas resulting from magnesium dissolved in hydrochloric acid is determined by water displacement and conversion of data to standard conditions.

16, Decomposition of Copper Carbonate Experiment
The purpose of decomposing CuCO3•Cu(OH)2 is to determine the volume of CO2 gas that evolves. In this experiment, the water displacement method is used to recover the gas evolved. The volume of CO2 collected is converted to dry conditions, which is then compared to the theoretical volume calculated.

17, pH Indicators Experiment
Dilutions are prepared of hydrochloric acid and sodium hydroxide in a 96-well plate. A different indicator is then added to each row and the resulting color changes are recorded.

18, Titration Strong Acid/Strong Base Experiment
A titration is done with a strong acid and a strong base of equal concentrations using microscale techniques.

19, Titration of Vinegar Experiment
A solution of sodium hydroxide of known concentration is used to titrate a known volume of vinegar to determine the amount of acetic acid that was present in the sample of vinegar.

20, Ksp for Calcium Hydroxide Experiment
In this experiment, students will use a measured volume of calcium hydroxide saturated solution and neutralize it with a solution of known concentration of hydrochloric acid. From the volume of acid used, the Ksp and the concentration of calcium hydroxide can be determined.

21, Puzzle Titration Experiment
The students will receive 5 chemical solutions stored in pipet storage devices. By mixing these chemicals two-at-a-time, they will determine as much as they can about their composition. If two or more chemicals have a similar chemical make-up, they will attempt to rank them according to their concentration.

22, Bronsted/Lowry Acids and Bases Experiment
The relative acidity of various salt solutions is determined by dissolving the crystals on pH paper and approximating the pH according to the color scale provided.

23, Solubility of Ammonia Experiment
Ammonia gas is produced by heating aqueous ammonia and collected in a Beral pipet. A bubble of the ammonia is then expelled into a beaker of water containing phenolphthalein and a small amount of water is allowed to enter the pipet. Ammonia's solubility is then observed.

24, Solution Formation Experiment
A number of polar and nonpolar liquids and solids are mixed in order to study their solubilities and miscibilities and the factors involved in the solution formation process.

25, Temperature and Solubility Experiment
A systematic study of the variation in the water solubility of a soluble salt with temperature is accomplished by filling the wells of a 12-well strip with solutions saturated at various temperatures and then cooling the strip, to near 0 °C.

26, Polar and Nonpolar Solvents Experiment
In this activity, the solubilities of seven solutes in two different solvents -- water (H2O), a polar solvent; and vegetable oil, a nonpolar solvent -- are studied.

27, Electrical Conductivity Experiment
The electrical conductivities of solutions of strong electrolytes, weak electrolytes, and nonelectrolytes are studied. This experiment is performed as a demonstration when the older and more dangerous conductivity apparatus is used. It may be performed as a student experiment when new apparatus is constructed.

28, Electrolysis Experiment
A variety of solutions are electrolyzed using an apparatus constructed from pencils and a 9 volt battery.

29, Activity Series (Reduction Potential) Experiment
Several metals and solutions containing metals are reacted to determine their order of activity.

30, Voltaic Cells Experiment
A voltmeter is used to rank metals from the most easily reduced to the most difficult to reduce.

31, Using Solubility Rules Experiment
Several solutions are mixed together to determine which combinations produce a precipitate and, if so, the nature of the precipitate. After all of the combinations are tried and the results recorded, the students are expected to be able to recognize the same chemicals in unlabeled containers.

32, Combining Cations and Anions Experiment
The relative solubility of some common salts is tested. Five of the salts have a common cation, sodium (Na+). The other five salts have the a common anion, nitrate (NO3-). The number of drops of each salt is kept constant, so that the only difference in mixtures is the cation from the first group and the anion from the second group.

33, Copper Ammine Complex Formation Experiment
Copper (II) ions are mixed with varying amounts of ammonia and observations are made.

34, Le Chatelier's Principle Experiment
Several equilibria (a pH indicator; a complex ion) are studied as stresses are introduced and conclusions about Le Chatelier's principle are made.

35, Six Solutions Experiment
The students will receive six chemicals to study: aqueous silver nitrate; aqueous sodium chloride; aqueous sodium carbonate; aqueous nitric acid; aqueous sodium bromide; and water.

After studying the reactions of known samples, students will have an opportunity to analyze an unknown.

36, Qualitative Analysis Experiment
Since safety is such an important factor in a chemistry experiment, this qualitative scheme has been designed to avoid the poisonous or carcinogenic chemicals found in many of the traditional schemes. We have developed a scheme which we feel will give good results for the first year student. If time is a factor, this lab may be done by eliminating the ions Al3+ and Zn2+.

This experiment may be performed using Pasteur pipets as well as "unpulled" Beral pipets. We calibrated "unpulled" Beral pipets and found they contained about 22 drops per milliliter. The number of drops given are to be considered as a guideline and may vary. Students should be made aware of this.

We recommend the use of Beral pipets to transfer acids and bases if possible. It is important to remind the students the proper procedures required in handling these substances and what to do if a spill occurs.

Always centrifuge to separate solids from supernatants if possible.

The option of making up the student sample is left to the teacher. You may decide whether to make up a general sample or whether to have the student make up their own. Each student sample should contain about three drops of each ion for a total volume close to 1 mL.

37, Iodine Clock Kinetics Experiment
The time after mixing that it takes for a mixture of hydrogen peroxide, starch, potassium iodide, and thiosulfate to turn blue is recorded and related to the concentration of certain reactants.

38, Kinetic Study of Thiosulfate in Acid Experiment
The acidification of thiosulfate solutions leads to the formation of colloidal sulfur. The rate of this reaction is studied by measuring the time required for the reaction mixture to become so turbid that is ceases to transmit light.

39, Halogen Chemistry Experiment
This experiment provides an opportunity to investigate the reactivity of some of the halogens ("salt-formers") in water solutions. The lab will be accomplished using microscale techniques and equipment.

40, Halide Ions Experiment
Students will mix solutions together, two at a time, on an acetate sheet and record any evidence of reaction. After completing this experiment, students should be able to identify these halogen ions: F-, Cl-, Br-, and I-.

41, Tests for Iron(II) and Iron(III) Ions Experiment
A number of experiments are done by mixing drops of two or more reagents and recording the results. At the end of this lab, students will be able to identify the iron(II), Fe2+, and iron(III), Fe3+ ions in solutions.

42, Silver Mirror Experiment
A mixture of honey, silver nitrate, ammonium nitrate, and sodium hydroxide is used to coat a test tube with silver. The principle of oxidation-reduction reactions is studied.

43, Esters Experiment
Students will prepare two esters of their choice and make observations of their properties.

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History

Early in the decade of the 1980s, a move began toward the downscaling of teaching laboratory experiments. In organic chemistry, Dana Mayo and Ronald Pike were among the recognized leaders. In college general chemistry, Stephen Thompson is perhaps the best known.

There has been an enormous upswelling of interest in downscaling, especially at the high school chemistry level. Jerry Bell and Miles Pickering have provided leadership in this area. Tom Russo and Bob Becker have proven to be among the most creative classroom teachers in terms of designing activities.

During the summer of 1988, a group of Nebraska high school chemistry teachers met at Lincoln East High School under support of the Nebraska Coordinating Commission for Postsecondary Education. Dianne Epp, Ed Lyons, and Dave Brooks served as the group leaders. Written materials developed at the 1987 Woodrow Wilson program served as a starting point. The Nebraska teachers worked and revised those materials. They also developed new materials.

No single person can claim leadership, and too many have made important contributions to risk naming some and thereby slighting others.

Just as we are unable to identify a single individual or small group of persons as being the leaders of this movement, we are also faced with the tremendous amount of development that is taking place. The Nebraska experiments, though improved relative to earlier versions, were neither polished nor extensively tested. Numerous improvements already have been identified, and still more new experiments developed and suggested -- too late to include in these draft materials.

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Using These Materials

In order to get information about microscale (a widely applied misnomer used to describe the downscaling movement) into the hands of teachers, the Nebraska project developed several tools. Currently only these write-ups are available from this Web site.

We do not see this as the first of a continuing series, but as a one-time set of working documents for teachers. The intent of these materials is to put ideas about "microscaling" into the hands of teachers and thereby catalyze further microscale development.

Interested parties are directed to Steve Thompson's book, ChemTrek, published by Allyn and Bacon.

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Why MicroScale?

Few microscale experiments are new. Instead, most of the experiments we see are 'smaller' versions of large-scale ones already familiar to us. Microscaling is currently in a period of both high development and sorting out. The development phase results from teachers inventing new ways to perform experiments, and, in a few cases, trying experiments that were inappropriate for academic laboratories when run at a higher scale. The materials in this package address the sorting out phase. While some features of the experiment write-ups have been made consistent, there remains a wide range of classroom strategy reflected by these materials. Many different classroom styles are possible. Whether some are generally more successful than others, or whether these will be teacher dependent -- with some teachers performing best one and others in a different way -- remains to be seen.

While the early days of this movement were supported for reasons of safety and economy, it has become clear that there are many pedagogical advantages to using experiments at the microscale. Also, there are some disadvantages. We are teachers of an exciting discipline at a time when research and development of suitable teaching activities is particularly easy and important for us to accomplish.

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Safety

The general wisdom of the microscale movement is that "smaller is safer." This may NOT be the case, especially as we create hands-on activities from those previously reserved for demonstration experiments.

Each procedure includes safety recommendations for the experiments. All of these are based upon teacher inputs, and most have been classroom tested with students. They should be thought of as minimum requirements, however, and not as overly cautious recommendations. Because microscale activities are breaking new academic ground, teachers are advised that the procedures may contain risks not heretofore recognized as a part of contemporary prudent practice.

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Suppliers
Flinn Scientific
P. O. Box 219
Batavia, IL 60510
(312)-879-6900

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Comments

Each lesson describes a microscale or downscaled activity thought by Nebraska teachers to be suitable for use in a secondary school chemistry classroom. Several of the activities may be used at lower grade levels. Others might be suitable for the college level.

The first draft of this information comes from the written materials prepared after the Nebraska MicroScale chemistry workshop, Summer 1988. Those drafts, in turn, often came from the earlier Woodrow Wilson/Dreyfus workshop.


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Last revised: 6/10/02