Chemical Properties

Observing Chemical Properties A chemical property is any ability to produce a change in the composition of matter.

Observing Chemical Properties Chemical properties can be observed only when the substances are changing into different substances. Flammability and reactivity are two examples of chemical properties.

Flammability Flammability is a material’s ability to burn in the presence of oxygen.

Reactivity Describes how quickly a substance combines chemically with other substances is reactivity.

Recognizing Chemical Changes A chemical change occurs when a substance reacts and forms one or more new substances. Three common types of evidence for a chemical change are: change in color the production of a gas the formation of a precipitate.

A Change in Color A change in color is a clue that a chemical change has produced at least one new substance. EX: As a match burns, it shrivels up and turns black. EX: Over time a shiny silver bracelet that is exposed to air will darken.

Production of a Gas Production in gas is a clue that a chemical change is happening. EX: bubbles

Formation of a Precipitate Any solid that forms and separates from a liquid mixture is called a precipitate. EX: If you add lemon juice or vinegar to milk, proteins in the milk undergo a chemical change that alters their structure and causes white solid bits to separate from the liquid (curdling of milk).

Is a Change Chemical or Physical? When matter undergoes a chemical change, the composition of the matter changes. When matter undergoes a physical change, the composition of the matter remains the same.