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Difficulty: MediumProperties of Matter

A maintenance technician needs to identify an unknown metal sample by evaluating its characteristics in a testing laboratory. Which of the following procedures tests a chemical property of the metal rather than a physical property?

  1. A
    Heating the metal sample in a furnace to determine the temperature at which it melts
  2. B
    Submerging the metal sample in a graduated cylinder to measure its water displacement volume
  3. Applying a drop of concentrated hydrochloric acid to observe whether hydrogen gas is producedAnswer
  4. D
    Weighing the metal sample on a spring scale to measure the gravitational force acting upon it

Answer

Applying a drop of concentrated hydrochloric acid to observe whether hydrogen gas is produced
Applying hydrochloric acid to observe gas production directly tests chemical reactivity, which is a chemical property because the metal undergoes a reaction to form new chemical substances (a metal salt and hydrogen gas).

Step-by-Step Solution

1
Define the difference between physical and chemical properties
Physical properties can be observed or measured without changing the chemical composition of the substance (e.g., melting point, density, mass, volume). Chemical properties describe how a substance interacts with other substances to form entirely new materials (e.g., reactivity with acid, flammability, oxidation).
Establishing the fundamental definitions allows proper classification of each lab procedure.
2
Evaluate the procedure testing reaction with acid
When acid is placed on the metal, the formation of hydrogen gas demonstrates a chemical reaction (M+2HCl→MCl2+H2M + 2HCl \rightarrow MCl_2 + H_2), altering the chemical bonds and forming new compounds.
A change in chemical composition indicates the measurement of a chemical property.

Key Concept

Distinction between physical properties (observable without altering composition) and chemical properties (observable only during a reaction that changes composition)
Estimated Time:1m 0s
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Topics

Properties of Matter

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