Assignment: Pre-laboratory

1. What are the independent and dependent variables?

2. Define at least three controlled variables.

3. State your hypothesis for today's experiment as an "if/then" statement.

Activity 1 Questions:

1. Was the hypothesis proven or disproven?

2. Were the results reproducible?

3. What could have been done to make the results more reproducible?

4. What variable was not completely controlled during the experiment, and what could have been changed to make this variable more constant?

Activity 2 Questions:

1. List five questions about the rate at which Alka-Seltzer® tablets dissolve. Think about the controlled variables. What would happen if temperature were held constant and one of the controlled variables were changed?

2. Develop a new hypothesis based on one of the questions. Remember that a hypothesis must be testable with empirical or measurable data. Fill in Activity 2 Table.

LABORATORY QUESTIONS

1. Graph the results of Activity 1.

a. What are the two variables that will be graphed?

b. Which is the independent variable? Should it be on the X- or Y-axis? Why?

c. Which is the dependent variable? Should it be on the X- or Y-axis? Why?

2. Can a straight line be drawn through the graphed Activity 1data points? What conclusions can be deduced from the slope of the line?

3. Predict how long it will take to dissolve an Alka-Seltzer® tablet in 200 mL of water at:

d. 35°C

e. 60°C

f. 80°C

4. Was the hypothesis for Activity 2 proven or disproven?

5. If the hypothesis was proven, should the experiment be deemed a failure or a success? Why?

6. If the hypothesis was disproven, should the experiment be deemed a failure or a success? Why?

7. Based on your results for Activities 1 and 2, list two other hypotheses and experiments aimed at understanding the factors that influence the rate at which Alka-Seltzer® tablets dissolve.

8. Share your results with your classmates. Based on a collection of the different hypotheses, experiments, and results, what are the most important factors influencing the rate at which Alka-Seltzer® tablets dissolve?