Pharmacy is Right for Me

Do-It-Yourself Experiments

The Effects of Temperature on Rate

Chemical reactions occur when the reactants (such as particles, atoms or ions) come into physical contact with one another, thus forming a product. When the frequency of the physical encounters increases, the rate at which products are formed also increases.

Using Alka-Seltzer^® tablets, this experiment illustrates that increasing the temperature of reactants can increase the rate of a chemical reaction.

6 clear cups
Measuring cup
Thermometer, -20 degrees C to 110 degrees C
3 Alka-Seltzer^®tablets
Stopwatch
Mortar and pestle
Source of hot water
Ice cubes
Graph paper

Hot Water

Run water from the hot tap until it is as hot as possible. Fill a clear glass with exactly 8 oz. of hot water.
Use the thermometer to take the water’s temperature and record it on your data sheet.
Remove 1 Alka-Seltzer® tablet from its package. Drop it into the water. Measure the time required for the tablet to fully dissolve. Be prepared to start and stop on time. The reaction will take less than 15 seconds. Record the time.

Room Temperature Water

Fill a clear glass with exactly 8 oz. of room temperature or lukewarm water.
Use the thermometer to take the water’s temperature and record it on your data sheet.
Drop 1 Alka-Seltzer® tablet into the water. Measure the time required for the tablet to fully dissolve. Record the time.

Cold Water

Fill a clear glass with 4 oz. of water and add enough ice to adjust the level to exactly 8 oz. Stir the water for about 15 seconds so the temperature will come to equilibrium.
Use the thermometer to take the water’s temperature and record it on your data sheet. (Leave the ice cubes in the water!)
Drop 1 Alka-Seltzer® tablet into the water. Measure the time required for the tablet to fully dissolve. Record the time.

* For more information about this and other Alka-Seltzer^® experiments, click HERE to check out the company’s Student Experiments page.

Create Plastic Milk

Try making plastic the way people did one hundred years ago by turning milk into a solid with this quick experiment.

Skim milk
White vinegar
Microwave-proof bowl
Strainer

Add 4 teaspoons of white vinegar to 1 ½ cups of skim milk.
Microwave the mixture for about one minute. After a minute the milk and vinegar should separate into two parts—a liquid and a solid.
Strain the liquid, so that only the milk curds remain; the protein in the curd allows it to act like rubber.

* Click HERE for more experiments from the PBS show “ZOOM”.

Does Listerine® Actually Kill Bacteria?

We can thank Joseph Lister for introducing the use of germ-killing antiseptics to hospitals, but how about seeing a germ-killing antiseptic at work with your own eyes? Try the experiment below to see if using Listerine® (the antiseptic mouthwash named for Lister) kills more bacteria than brushing alone.

3 agar petri dishes
3 disinfected swabs
1 bottle of disinfected water
3 toothbrushes
1 tube of toothpaste
1 marker pen
1 ruler

Remove petri dishes from refrigerator and allow them to warm to room temperature.
Label each dish and each toothbrush either A, B, or C.
Toothbrush A is used to brush teeth 2 times a day for 5 days with only water. After brushing, the toothbrush is kept in an empty cup.
Toothbrush B is used to brush teeth 2 times a day for 5 days using toothpaste. After brushing, the toothbrush is kept in an empty cup.
Toothbrush C is used to brush teeth 2 times a day for 5 days using toothpaste. After brushing, the toothbrush is kept in a cup filled with Listerine®. At the end of five days, dampen each sterilized swab with sterilized water, then brush over corresponding toothbrush. Wipe brush over corresponding petri dish. Cover each petri dish and keep in cool shaded place for bacteria to grow over the course of several days.
Measure diameter of the bacteria colony in each dish, then record your findings.Which dish had the smallest bacteria colony? Does Listerine® kill more bacteria than toothpaste alone?