© Division of Chemical Education  • www.JCE.DivCHED.org  •  Vol. 85 No. 8 August 2008  •  Journal of Chemical Education 1061

Chemistry for Everyone

We have constructed a simple device from plastic cham-pagne cups to provide a novel way of demonstrating the colors of acid–base indicators. The apparatus can also be used to dem-onstrate chemiluminescence. For younger students, the chemical fountain effectively shows the mixing of primary colors using supermarket food colors.

Materials

Seven plastic champagne cups, with the detachable bases removed

Piece of clear, acrylic tubing, ~26 in. long

Glue, clear-dry caulking, and caulking gun

Block of wood (e.g., pine), ~8 in. × 8 in. × 2 in. with 5/8 in. hole drilled in the center

Teflon tape

Erlenmeyer flask, 500 mL, containing ~500 mL water

Several indicators (e.g., methyl orange, bromothymol blue, methyl red, bromocresol green, universal indicator)

50 mL 0.1 M HCl and 50 mL 0.1M NaOH solutions

Food coloring (red, yellow, blue)

Copper/luminol solution for demonstrating chemilumi-nescence (1)

Construction of Fountain

Seven plastic champagne cups, with the stems removed, are glued equal distances apart along a length of clear acrylic tubing. The top six cups have holes drilled in them so that the solutions drain from one cup to the next and create the fountain effect (Figure 1). The assembly is secured in a wooden base that also serves as a drain to prevent overflow when the bottom cup fills up. The preparation of the chemical fountain apparatus is not difficult and construction can be completed in a couple of hours, but the assembly should be left for several days to allow the glue and caulking to dry completely. The wooden base used to support the apparatus is placed over a beaker to collect the overflow. For appearance and to protect the wood, the wooden base may be painted. Although we examined several designs for the chemical fountain (e.g, gluing the cups together or con-

necting them with rubber stoppers), we found the arrangement described here works well. Attaching the cups to a sturdy piece of tubing gives the structure rigid support and allows for conve-nient drainage. Sources for construction materials and detailed instructions for assembling the chemical fountain are provided in the online supplement.

Hazards

Wear safety goggles and rubber gloves when handling hydrochloric acid, sodium hydroxide, and hydrogen peroxide solutions. All three can cause chemical burns. The used solutions should be flushed down the drain with plenty of water. Safety goggles should be worn and care taken when using power tools in the construction of the chemical fountain.

Colorful Chemical Fountainssubmitted by: Nicholas C. Thomas* and Stephen Faulk Department of Chemistry, Auburn University Montgomery, Montgomery, AL 36124-4023; *nthomas@aum.edu

checked by: Catherine Banks Department of Chemistry, Peace College, Raleigh, NC 27604

JCE DigiDemos: Tested Demonstrations edited by

Ed VitzKutztown University

Kutztown, PA 19530

Figure 1. Methyl red fountain (left) and chemiluminescent fountain (right). (A color version of this image can be found on p 1013 of the table of contents.)

1062 Journal of Chemical Education  •  Vol. 85 No. 8 August 2008  • www.JCE.DivCHED.org  • © Division of Chemical Education

Chemistry for Everyone

Method

Acid–Base FountainPlace 5–10 drops of indicator in the top cup. Add 5 drops

of 0.1 M HCl to the fourth cup. Slowly pour water from the Erlenmeyer flask into the top cup until the bottom cup begins to fill up. When using universal indicator, add 10–15 drops of indicator to the top cup, 5 drops of 0.1 M HCl to the third cup, and 6 drops of 0.1 M NaOH solution to the sixth cup.

Chemiluminescent Fountain

Prepare the copper/luminol solution as previously de-scribed (1). Place 2 drops of 30% H2O2 into each cup. Dim the room lights and slowly pour the copper/luminol solution into the top cup until the bottom cup begins to fill up.

Food Coloring Fountain

Place 1 drop of the red food coloring in the top cup and 1 drop of blue or yellow food coloring in the fourth cup. Fill the fourth cup first, then quickly fill the top cup. Continue adding water to the top cup until the bottom cup begins to fill. Repeat using other combinations of food colorings.

Discussion

These chemical fountains are simple to perform in a moderate-sized classroom and provide an impressive display for students. It is possible to demonstrate both color ranges of an indicator at once, as well as the intermediate color change. For instance, when methyl red is used, the top cups are yellow indicating methyl red’s color at a pH of ~5 or greater while the lower cups turn red on contact with acid. A transitional orange color can be seen as the two colors mix, which represents the indicator color change range. When universal indicator is used, sodium hydroxide solution is also placed in one of the cups to indicate the range of colors (neutral green in the top cup, pink in middle with acid, and blue with base at the bottom).

Chemiluminescence has been demonstrated by a number of procedures reported in the Journal (e.g., 1–3). The chemilu-minescent fountain described here is especially impressive, and the effect is clearly visible in the largest of darkened rooms. For younger classes, or if chemical indicators are unavailable, we have also found the chemical fountain effectively demonstrates the mixing of primary colors using supermarket food colorings.

Because a drain is built into the base, the fountain operates cleanly and the contents of the overflow beaker can be washed down the drain. To clean the fountain between demonstrations, fresh water should be flushed through the cups. Any residual liquid remaining in the cups can be removed by tipping the as-sembly over a large sink.

In time, the caulking used as sealant may stain slightly ow-ing to the indicators. This has little effect on the demonstration, and the caulking can easily be removed and replaced if necessary. In a large classroom, placing a piece of white cardboard behind the acid–base fountain will also improve visibility.

Many modifications to the chemical fountain are possible. For instance, more cups can be added if a longer piece of tubing is used. Ten to twelve stacked cups are especially effective with the chemiluminescence fountain. A small electric aquarium pump (e.g., Via Aqua 80 model submersible pump with vari-able control) can also be used to recycle the waste water back to the top cup to produce a continuous acid–base fountain. If needed, the tubing attached between the pump and fountain can be lengthened to slow the water flow. A pinch clamp can also be used to control the water circulation. Once the flow of water has been regulated to be constant, drops of acid or base can be added alternatively to the top cup to create a continually changing series of indicator colors. Students quickly learn which colors are associated with each indicator.

Literature Cited

1. Thomas, N. C. J. Chem. Educ. 1990, 67, 339. 2. Chalmers, J. H., Jr.; Bradbury, M. W.; Fabricant, J. D. J. Chem.

Educ. 1987, 64, 969. 3. Shakhashiri, B. Z.; Williams, L. G.; Dirreen, G. E.; Francis, A. J.

Chem. Educ. 1981, 58, 70.

Supporting JCE Online Materialhttp://www.jce.divched.org/Journal/Issues/2008/Aug/abs1061.html

Abstract and keywords

Full text (PDF) Links to cited JCE articles Color figures

Supplement Instructions for the chemical fountain assembly

JCE Featured Molecules for August 2008 (see p 1152 for details) Structures of some of the molecules discussed in this article are

available in fully manipulable Jmol format in the JCE Digital Library at http://www.JCE.DivCHED.org/JCEWWW/Features/MonthlyMolecules/2008/Aug/.

JCE Cover for Jaunary 2005 An alternative chemiluminescent fountain configuration can be

seen on the cover of the January 2005 issue of JCE (http://www.jce.divched.org/Journal/Issues/2005/Jan/cover.html).

Colorful Chemical Fountains

Nicholas C. Thomas* and Stephen Faulk

Chemistry Department

Auburn University Montgomery

Montgomery, AL 36124-4023

Online instructions for chemical fountain assembly Caution: You will need standard woodworking tools (scroll saw, high-speed drill,

regular drill) to cut the materials. Be sure you know how to use these tools safely.

Since the plastic cups are made of brittle plastic, they must be held tightly, and cut

slowly and carefully. Always use extreme caution when using electric cutting and

drilling tools and wear safety glasses.

Materials

Seven plastic champagne cups, with the detachable bases removed.

~ 26" piece of clear, acrylic tubing

Glue; clear-dry caulking, and caulking gun

Block of wood (eg pine), ~ 8" x 8" x 2" with 5/8" hole drilled in the center

Teflon tape

1-500 mL Erlenmeyer flask containing ~500 mL water

Several indicators (eg methyl orange, bromothymol blue, methyl red, bromocresol

green, universal indicator)

50 mL 0.1 M HCl and 50 mL 0.1 M NaOH solutions

Food coloring (red, yellow, blue)

Copper/luminol solution for demonstrating chemiluminescence (1)

Sources for materials

Plastic champagne cups with removable stems are available from nationwide party

supply stores such as Party City and online stores (eg www.partyoptions.net).

Acrylic tubing may be available at local hardware stores or Home Centers. It is

also available online from Delvies Plastics (www.delviesplastics.com) for under $2

(plus a hefty shipping charge) for a 36" length piece with outside diameter 5/8",

inside diameter ½" and wall diameter 1/16." However, we had a supply of acrylic

burets on hand and found these to be convenient to use. The graduation marks can

be easily removed with acetone. These burets are available from Cynmar

Corporation (www.cynmar.com) or Wards Scientific (www.wards.com) and cost

about $19.00 for a 26" long, 50 mL buret.

Procedure

1. Remove the base from a plastic champagne cup [Fig 1]. Place the cup on a

bench and using a high-speed drill, drill four 1/16 inch holes equidistant

apart in the bottom of the cup [Fig 2]. Drill similar holes in 5 more cups. The

use of a drill is recommended since this produces holes of equal size,

resulting in uniform drainage from each cup.

Figure 1 Figure 2

2. Using an electric scroll saw, cut the stem of each cup approximately 2" from the

end [Fig 3]. Also cut the stem from a seventh cup which does not have holes

drilled in it. This will be the bottom cup. Since the plastic is brittle, slow cutting

using a high blade speed is required to prevent the plastic shattering. Insert the

acrylic tubing through the seventh cup, the one without holes, [Fig 4]. It may be

necessary to vary how much of the stem is cut off of each cup to insure the fit is

tight and the cups will not slide too easily along the tubing. (If the cups do not

make a tight fit, they will slip during gluing and will require clamping until the

glue dries).

Figure 3 Figure 4

3. Use a marking pen to mark the tubing about ½" below where the rim of the

bottom cup will be [Fig 5]. This will be where drainage holes are drilled in the next

step.

Figure 5

4. Remove the cup from the tubing and use a high-speed drill fitted with a 1/8th

inch bit to drill two holes on opposite sides of the tubing at the mark made in step

3. These holes will allow the liquid in the bottom cup to drain out through the

tubing into a waste container below.

5. Thread the bottom cup back onto the tube and glue it in place. Make sure the cup

is centered on the tubing. Allow the glue to dry before proceeding to the next step.

6. Use a caulking gun to place a bead of water-based, clear-dry caulking in the

space between the inside of the cup and the tubing [Fig 6]. Wearing rubber gloves,

use a finger to spread the caulking evenly to ensure the gap is filled. If this area is

not caulked, the chemicals do not mix fast enough.

Figure 6

7. Thread the other six cups on the tubing so they will be roughly the same distance

(~2-3") apart from each other [Fig 7]. Mark their positions on the tubing with a

pen. Remove all but one of the cups and glue it in place above the bottom cup at

the mark, then caulk as in step six. Repeat with the remaining cups.

Figure 7

8. Drill a 5/8th-inch hole all the way though the center of the wooden base so that

the bottom of the tubing will fit snugly into the hold. The base may be painted if

desired. If needed, use Teflon tape wrapped around the base of the tubing to

achieve a tight fit [Fig 8]. The size of the hole in the base will obviously depend on

the diameter of the tubing.

Figure 8

9. Let the apparatus stand for at least 1-2 days to ensure the caulking dries

completely.

To perform the demonstration, stand the fountain on a large beaker to catch the

overflow [Fig 9]. Pour liquid slowly into the top cup.

Figure 9