Examples of Physical Properties A physical property is any characteristic of a material that can be observed or measured without changing the ________________ of the substances in the material. Viscosity, conductivity, malleability, hardness, melting point, boiling point, and density are examples of physical properties.
Examples of Physical Properties Viscosity The tendency of a liquid to keep from________is called its viscosity. Thick liquids, such as corn syrup and honey, have a high viscosity. Thin liquids, such as vinegar and water, have a low viscosity.
Examples of Physical Properties Conductivity A material’s ability to allow_____to flow is called conductivity. Materials that have a high conductivity, such as metals, are called conductors. Good conductors of heat are usually also good conductors of electricity.
Examples of Physical Properties Malleability The ability of a solid to be___________without shattering is malleability. Most metals, such as gold, are malleable. An ice cube or piece of glass breaks into small pieces when struck with a hammer. Solids that shatter when struck are brittle, not malleable.
Examples of Physical Properties Hardness One material can____________another material if it is harder than the other material. A kitchen knife can scratch a copper sheet because stainless steel is harder than copper. The material used to sharpen the knife blade must be harder than stainless steel. Diamond is the hardest known material.
Examples of Physical Properties Melting and Boiling Points The temperature at which a material changes state is a physical property. The temperature at which a substance changes from solid to liquid (______) is its melting point. The temperature at which a substance changes from liquid to gas (________) is its boiling point.
Examples of Physical Properties Melting and Boiling Points Which of these substances are liquids at room temperature (20C, or 68F)? Answer: octane, water, and ______________
Examples of Physical Properties Density The ratio of the mass of a substance to its volume is its density. Density can be used to test the___________of a substance. Silver has a density of 10.5 g/cm3. A coin with a density of 9.9 g/cm3 is not made from silver, or it contains substances in addition to silver.
Using Physical Properties Using Properties to Identify Materials Physical properties are used to identify a material, to choose a material for a specific purpose, or to separate the substances in a mixture. To ______________: Decide which properties to test. Do tests on a sample of the unknown material. Compare the results with the data reported for known materials.
Using Physical Properties Using Properties to Choose Materials To___________which materials are chosen for which uses: For example, shoelaces must be flexible, that is they must be able to bend without breaking. They must also be durable, that is, they must be able to withstand repeated use.
Using Properties to Separate Mixtures Filtration and distillation are two common separation methods for mixtures. Filtration You can separate hot tea from loose tea leaves by pouring the mixture through a strainer. Filtration is a process that separates materials based on the size of their_____________________.
Using Properties to Separate Mixtures These students filter (sift) dirt through a wire screen to locate small objects. Particles of dirt are small enough to pass through the holes, but objects such as broken bits of pottery are too large.
Using Properties to Separate Mixtures Distillation Sometimes all the particles in a solution are small enough to pass through a filter. Distillation is a process that separates the substances in a solution based on their _______________________.
Recognizing Physical Changes The change of water from a liquid to a gas during boiling is a physical change. A physical change occurs when some of the properties of a material change, but the substances in the material ________________________________. During a physical change, the size and shape of a material can change but not the____________. Some examples include melting butter in a pan crumpling a piece of paper slicing a tomato
Recognizing Physical Changes Some but not all physical changes can be ____________. Braiding hair is a reversible change. Cutting hair cannot be reversed.