(credit a: modification of work by “95jb14”/Wikimedia Commons credit b: modification of work by “mjneuby”/Flickr) (b) Steam condensing inside a cooking pot is a physical change, as water vapor is changed into liquid water. In each of these examples, there is a change in the physical state, form, or properties of the substance, but no change in its chemical composition.įigure 1.3.1 (a) Wax undergoes a physical change when solid wax is heated and forms liquid wax. Other examples of physical changes include magnetizing and demagnetizing metals (as is done with common antitheft security tags) and grinding solids into powders (which can sometimes yield noticeable changes in color). We observe a physical change when wax melts, when sugar dissolves in coffee, and when steam condenses into liquid water ( Figure 1.3.1). A physical change is a change in the state or properties of matter without any accompanying change in its chemical composition (the identities of the substances contained in the matter). Other physical properties, such as the melting temperature of iron or the freezing temperature of water, can only be observed as matter undergoes a physical change.
We can observe some physical properties, such as density and color, without changing the physical state of the matter observed. Familiar examples of physical properties include density, color, hardness, melting and boiling points, and electrical conductivity. A physical property is a characteristic of matter that is not associated with a change in its chemical composition. The characteristics that enable us to distinguish one substance from another are called properties. Identify properties of matter as extensive or intensive.Identify properties of and changes in matter as physical or chemical.
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