An environmental engineer conducted an experiment to evaluate wastewater purification efficiency. She prepared three identical filtration columns containing different concentrations of activated charcoal (, , and ). For all trials, she maintained a fluid temperature of , a flow rate of , and an initial methylene blue dye concentration of . She recorded the time required to achieve decolorization of the solution in each column.
Match each experimental component on the left with its correct variable classification on the right.
- Concentration of activated charcoal in the filtration columnIndependent variable (manipulated factor)
- Time required to achieve decolorizationDependent variable (measured outcome)
- Initial methylene blue dye concentration ()Controlled variable (constant condition)
Answer
The concentration of activated charcoal is matched with Independent variable; the time required to achieve 99% decolorization is matched with Dependent variable; the initial dye concentration is matched with Controlled variable.
In experimental design, the independent variable is manipulated directly by the experimenter (activated charcoal concentration), the dependent variable is the outcome measured in response to those manipulations (time required for decolorization), and controlled variables are conditions held constant throughout all trials (initial dye concentration of ).
Step-by-Step Solution
Key Concept
Identifying Independent, Dependent, and Controlled Variables