Alka-Seltzer Lab

Alka-Seltzer Lab

Problem/Question: What type of liquid will cause an Alka-Seltzer tablet dissolve the fastest?

Background:

The fizzing you see when you drop an Alka-Seltzer tablet in water is the same sort of fizzing that you see from baking powder. A baking powder reaction is caused by an acid reacting with baking soda (sodium bicarbonate).

If you look at the ingredients for Alka-Seltzer, you will find that it contains citric acid and sodium bicarbonate (baking soda). When you drop the tablet in water, the acid and the baking soda react -- this produces the fizz. You can think of an Alka-Seltzer tablet as compressed baking powder with a little aspirin mixed in.

Materials:

Alka-Seltzer, Beakers, Stopwatch, graduated cylinder, flask, oil, water, vinegar, soda

Hypothesis:

If ______Then______

Identify the variables:

Independent Variable in this experiment is ______

The dependent variable in this experiment is ______

The control variables in this experiment are ______

Procedure:

A.  Water

1.  Measure 100mL of water using a graduated cylinder.

2.  Pour water into beaker.

3.  Place one Alka-Seltzer tablet into the beaker.

4.  Observe and measure the amount of time it takes for the tablet to dissolve. Record observations.

5.  Empty contents of beaker into receptacle.

B.  Vinegar

1.  Measure 100mL of vinegar using a graduated cylinder.

2.  Pour vinegar into beaker.

3.  Place one Alka-Seltzer tablet into the beaker.

4.  Observe and measure the amount of time it takes for the tablet to dissolve. Record observations.

5.  Empty contents of beaker into receptacle.

C.  Oil

1.  Measure 100mL of oil using a graduated cylinder.

2.  Pour oil into beaker.

3.  Place one Alka-Seltzer tablet into the beaker.

4.  Observe and measure the amount of time it takes for the tablet to dissolve. Record observations.

5.  Empty contents of beaker into receptacle.

Data

Alka Seltzer Dissolving Rates in Various Concentrations of Vinegar

Volume of Vinegar / Time to Dissolve (sec)
Trial 1 / Time to Dissolve (sec)
Trial 2 / Time to Dissolve (sec)
Average
0 mL
10 mL
30 mL
50 mL

Data:

Create a bar graph of the reduced data (your averages). Don’t forget.... all graphs need TAILS (title, axis, increments, labels, and scale).

Analysis:

What does the data say? Describe the data.

Conclusion:

Write a conclusion. Answer you original question. (Does the type of liquid effect how fast Alka-Seltzer tablets dissolve?) Accept or reject your hypothesis. Use actual data [real numbers] to provide evidence for what you say. Identify any sources of error.

Post-lab Questions:

1.  What was the control group in your experiment?

2.  What was the test variable? How do you know?

3.  What was the outcome variable? How do you know?

4.  Why did it dissolve at a different rate when vinegar was added?

5.  Design an experiment to test your answer to number 4.