Flammability is a chemical property of matter. This characteristic describes a substance’s ability to undergo a chemical change, specifically burning, which transforms it into entirely new substances.
What Defines a Chemical Property
A chemical property describes a substance’s capacity to participate in a chemical reaction, leading to the formation of new materials. These properties become apparent only when a substance undergoes a change in its chemical composition. For instance, the ability of iron to combine with oxygen and water to form rust is a chemical property; this process, known as corrosion, alters the iron into a different substance (iron oxide). Other examples include a substance’s reactivity with acids or bases, its toxicity, or its chemical stability under specific conditions.
What Defines a Physical Property
In contrast, a physical property can be observed or measured without altering the substance’s chemical identity. These characteristics do not involve a change in the substance’s fundamental makeup. Examples include a substance’s color, density, melting point, boiling point, hardness, and state of matter (solid, liquid, or gas). Observing these properties, such as noting that water boils at 100°C or that gold is yellow, does not result in the creation of a new substance. The material retains its original chemical composition throughout the observation or measurement.
Flammability and Chemical Change
Flammability is the capacity of a substance to burn or ignite, leading to fire or combustion. This characteristic is classified as a chemical property because burning is a chemical reaction. During combustion, a substance reacts rapidly with oxygen, typically producing heat, light, and new chemical compounds such as carbon dioxide and water vapor. For example, when wood burns, it transforms into ash, smoke, and gases, which are chemically distinct from the original wood.
Recognizing Chemical and Physical Transformations
Chemical properties are evident during chemical changes, which are processes where substances are converted into new substances with different properties. Examples of chemical changes include cooking an egg, which irreversibly alters its proteins, or the rusting of iron, which forms iron oxide. Physical properties are observed during physical changes, where a substance’s form or appearance changes, but its chemical identity remains the same. Examples include melting an ice cube into liquid water, boiling water into steam, or dissolving sugar in water. Breaking glass or tearing paper are also physical changes, as the material’s chemical composition does not change, only its size or shape.