Question

1. write a research question, using the format suggested in the read this! box, for the experiments alka - seltzer® and vinegar — boiling points of alcohols —
2. a student wonders, “will changing the volume of alcohol in a boiling point experiment change the boiling point of the liquid?” identify the variables that should be considered in this experiment.

independent
dependent
controlled

Explanation:

Question 13: Identifying Variables in Boiling Point Experiment

Independent Variable:

The independent variable is the one that is manipulated or changed in an experiment. In this case, the student is changing the volume of alcohol. So the independent variable is the volume of alcohol.

Dependent Variable:

The dependent variable is the one that is observed or measured to see the effect of the independent variable. Here, the student is interested in how the boiling point of the liquid changes. So the dependent variable is the boiling point of the liquid (alcohol).

Controlled Variables:

Controlled variables are the factors that are kept constant to ensure a fair test. For a boiling point experiment with alcohol, some controlled variables could be:

• The type of alcohol (e.g., using the same type like ethanol throughout the experiment).
• The atmospheric pressure (since boiling point depends on pressure; conducting the experiment at a constant pressure, like standard atmospheric pressure).
• The heating source and its power (using the same heater with the same power to ensure consistent heating).
• The container used (using the same type and size of container to avoid differences in heat transfer).

Final Answer (for Question 13):

• Independent Variable: Volume of alcohol
• Dependent Variable: Boiling point of the liquid (alcohol)
• Controlled Variables: Type of alcohol, atmospheric pressure, heating source power, container type/size (and other relevant constant factors)

Answer:

Question 13: Identifying Variables in Boiling Point Experiment

Independent Variable:

The independent variable is the one that is manipulated or changed in an experiment. In this case, the student is changing the volume of alcohol. So the independent variable is the volume of alcohol.

Dependent Variable:

The dependent variable is the one that is observed or measured to see the effect of the independent variable. Here, the student is interested in how the boiling point of the liquid changes. So the dependent variable is the boiling point of the liquid (alcohol).

Controlled Variables:

Controlled variables are the factors that are kept constant to ensure a fair test. For a boiling point experiment with alcohol, some controlled variables could be:

• The type of alcohol (e.g., using the same type like ethanol throughout the experiment).
• The atmospheric pressure (since boiling point depends on pressure; conducting the experiment at a constant pressure, like standard atmospheric pressure).
• The heating source and its power (using the same heater with the same power to ensure consistent heating).
• The container used (using the same type and size of container to avoid differences in heat transfer).

Final Answer (for Question 13):

• Independent Variable: Volume of alcohol
• Dependent Variable: Boiling point of the liquid (alcohol)
• Controlled Variables: Type of alcohol, atmospheric pressure, heating source power, container type/size (and other relevant constant factors)