Question detail
In a laboratory experiment, a student observes that the rate of the reaction between iron filings and hydrochloric acid is higher when the filings are crushed into a fine powder. What is the most likely reason?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Rate of reaction
Question
- A. The iron filings are more pure when powdered.
- B. The acid concentration is higher in the powdered sample.
- C. The powdered filings have a greater surface area available for collision.
- D. The reaction is exothermicand the powder heats up faster.
Answer
The powdered filings have a greater surface area available for collision.
Explanation
The correct answer is The powdered filings have a greater surface area available for collision.. This answer directly addresses the question: In a laboratory experiment, a student observes that the rate of the reaction between iron filings and hydrochloric acid is higher when the filings are crushed into a fine powder. What is the most likely reason? It matches the approved Chemistry 8462 learning objective and the linked subtopic. The other options are incorrect because they either change the rate, catalyst, reversible reaction, equilibrium, or graph context, or they do not answer the exact point being tested.
Common mistake
Misunderstanding Surface Area Effect
Students often think that increasing surface area speeds up reactions because it increases the amount of reactant rather than the number of exposed particles available for collisions.
Emphasize that increasing surface area allows more particles to be exposed and available for collisions, which increases the frequency of collisions and thus the reaction rate.
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