Classify each of the following as a physical or a chemical property. a. Iron and oxygen form rust. b. Iron is more dense than aluminum. c. Magnesium burns brightly when ignited. d. Oil and water do not mix. e. Mercury melts at39
The Correct Answer and Explanation is:
Classification:
a. Iron and oxygen form rust – Chemical Property
b. Iron is more dense than aluminum – Physical Property
c. Magnesium burns brightly when ignited – Chemical Property
d. Oil and water do not mix – Physical Property
e. Mercury melts at -39°C – Physical Property
Explanation:
Properties of matter are classified into two broad categories: physical properties and chemical properties.
Physical properties are characteristics of a substance that can be observed or measured without changing its chemical identity. These include density, melting point, color, boiling point, state of matter, and solubility. For example, iron is more dense than aluminum (b) is a physical property because density is a measurable trait that does not alter the substance. Similarly, oil and water not mixing (d) is a physical property because it’s due to differences in polarity and doesn’t change the chemical structure of either substance. The melting point of mercury (e) is also physical, as melting does not alter mercury’s identity—it’s still mercury before and after melting.
On the other hand, chemical properties describe a substance’s ability to undergo changes that transform it into a different substance. These are observed during chemical reactions. Iron forming rust (a) is a chemical property because rusting changes iron into iron oxide, a new substance. Likewise, magnesium burning brightly (c) is a chemical property; during combustion, magnesium reacts with oxygen to form magnesium oxide, altering its chemical makeup.
Understanding these distinctions is important in chemistry because they determine how substances interact and change. Physical properties help in identifying and separating substances, while chemical properties reveal how substances behave in reactions and what new substances can be formed.
