1.5: chemical and physical properties and changes
properties and changes
- change: the act of making something different or undergoing a process that makes something different
- physical change: a change during which the identity of the underlying substance does not change
- eg. melting, dissolving, boiling
- chemical change: a change during which something new is formed
- evidence of chemical change
- evolution of a gas
- change in color
- formation of a precipitate
- release or absorption of energy
- eg. release of heat, light, sound, change of temperature
- property: a quality, attribute, or characteristic of something
- physical property: a property of matter that can be observed without changing the substance
- eg. color, density, conductivity, physical state, solubility
- chemical property: a property of matter desccrived as a substance’s ability to participate in chemical reactions; to observe a chemical property, the substance must be changed
- eg. reactivity with oxygen, flammability, reactivity with acids
- intensive property: a property independent of the amount of material in the sample
- eg. density, boiling point, color, fammability, conductivity
- extensive property: a property dependent on the amount of material in the sample
separating mixtures
- mixtures can be separated based on the physical properties of the components in the mixtures
- separation methods include:
- filtration (separation by size)
- distillation (separation by boiling point)
- can separate a homogeneous mixture into its components
- chromatography (separation by solubility)