Identify the following as a chemical (C) or physical property (P):
. blue color
. melting point
. density
reacts with water flammability (burns)
hardness solubility (dissolves)
. boiling point
. reacts with acid
. luster
. supports combustion
. odor
. sour taste
. reacts with air
The Correct Answer and Explanation is:
To classify the given properties as either chemical (C) or physical (P), we can analyze each property based on its definition:
- Blue color – Physical Property (P)
- Melting point – Physical Property (P)
- Density – Physical Property (P)
- Reacts with water – Chemical Property (C)
- Flammability (burns) – Chemical Property (C)
- Hardness – Physical Property (P)
- Solubility (dissolves) – Physical Property (P)
- Boiling point – Physical Property (P)
- Reacts with acid – Chemical Property (C)
- Luster – Physical Property (P)
- Supports combustion – Chemical Property (C)
- Odor – Physical Property (P)
- Sour taste – Physical Property (P)
- Reacts with air – Chemical Property (C)
Explanation:
Physical properties are characteristics that can be observed or measured without changing the substance’s chemical identity. For example, the blue color, melting point, density, hardness, solubility, boiling point, luster, odor, and sour taste all refer to inherent qualities of a substance. These properties can be observed directly or measured with instruments, and they do not alter the chemical composition of the material being examined. For instance, when water is frozen, its physical state changes (liquid to solid) but remains H₂O.
On the other hand, chemical properties describe how a substance interacts with other substances, leading to a change in chemical composition. Properties such as reacting with water, flammability, reacting with acid, supporting combustion, and reacting with air all indicate the potential of a substance to undergo a chemical reaction. For example, flammability describes a material’s ability to burn, which involves a chemical change as it reacts with oxygen and produces heat, light, and new substances (such as carbon dioxide and water).
In summary, understanding the distinction between physical and chemical properties is crucial in chemistry. Physical properties can be observed without altering the substance, while chemical properties reveal how a substance behaves in chemical reactions, indicating its reactivity and potential transformations.