Question

read this!
when designing an experiment, you need to consider three types of variables. the independent variable is changed by the experimenter by design. this variable is sometimes called the “manipulated variable.” the dependent variable is what changes as a result of the change in the independent variable. this is sometimes called the “responding variable.” in some cases more than one dependent variable change the outcome of the experiment, but since you are not studying them, you need to keep them constant in each trial.

1. identify the independent, dependent, and controlled variables for the experiments that produced the data shown in model 2 and model 3.

table with rows: model experiment, alka-seltzer® and vinegar, boiling points of alcohols; columns: variables (independent, dependent, controlled)

Explanation:

To solve for identifying variables in each experiment, we analyze each model:

1. Alka - Seltzer® and Vinegar

• Independent Variable: The factor we change. For example, the amount of Alka - Seltzer or Vinegar (e.g., different masses of Alka - Seltzer added to a fixed amount of Vinegar).
• Dependent Variable: The outcome we measure. This could be the amount of gas produced (like the volume of CO₂) or the time taken for the reaction to complete.
• Controlled Variables: Factors we keep constant. Such as the volume of Vinegar, the temperature of the reaction environment, the type of container used.

2. Boiling Points of Alcohols

• Independent Variable: The type of alcohol (e.g., methanol, ethanol, propanol).
• Dependent Variable: The boiling point (measured in °C or °F).
• Controlled Variables: The pressure (usually atmospheric pressure, so we keep the pressure constant), the amount of alcohol (we use the same volume or mass of each alcohol sample), the heating rate (we heat each sample at the same rate).

For a table - based answer:

Model Experiment	Independent Variable	Dependent Variable	Controlled Variables
Boiling Points of Alcohols	Type of alcohol	Boiling point	Pressure, amount of alcohol, heating rate

Answer:

To solve for identifying variables in each experiment, we analyze each model:

1. Alka - Seltzer® and Vinegar

• Independent Variable: The factor we change. For example, the amount of Alka - Seltzer or Vinegar (e.g., different masses of Alka - Seltzer added to a fixed amount of Vinegar).
• Dependent Variable: The outcome we measure. This could be the amount of gas produced (like the volume of CO₂) or the time taken for the reaction to complete.
• Controlled Variables: Factors we keep constant. Such as the volume of Vinegar, the temperature of the reaction environment, the type of container used.

2. Boiling Points of Alcohols

• Independent Variable: The type of alcohol (e.g., methanol, ethanol, propanol).
• Dependent Variable: The boiling point (measured in °C or °F).
• Controlled Variables: The pressure (usually atmospheric pressure, so we keep the pressure constant), the amount of alcohol (we use the same volume or mass of each alcohol sample), the heating rate (we heat each sample at the same rate).

For a table - based answer:

Model Experiment	Independent Variable	Dependent Variable	Controlled Variables
Boiling Points of Alcohols	Type of alcohol	Boiling point	Pressure, amount of alcohol, heating rate