2.2. Classification of Matter http://www.ck12.org
Heterogeneous Mixtures
Heterogeneous mixtureshave visibly distinguishable parts. These mixtures will typically exist in the solid or liquid
states, but not the gas state. Gas state heterogeneous mixtures are not possible because gas particles freely mix and
disperse. Heterogeneous mixtures are quite common. For example, oil-and-vinegar salad dressing is a heterogeneous
mixture that is in the liquid state. Its composition varies and typically includes olive oil mixed with red vinegar. An
example of a solid heterogeneous mixture is soil. Soil is primarily comprised of organic and inorganic material,
including substances like decaying plants and animals, minerals, water, and air. The composition of soil varies
greatly from one location to another.Figure2.8 shows these mixtures.
FIGURE 2.8
Examples of heterogeneous mixtures:
(left) oil and vinegar and (right) soil.The substances that comprise heterogeneous mixtures can also be separated by physical means. We will discuss
separation techniques in the following lesson.
Lesson Summary
- Matter exhibits specific physical and chemical properties.
- Matter can exist in one of three states: solid, liquid, or gas.
- In the solid state, particles are fixed in place relative to one another. In the liquid and gas states, individual
particles are free to move. - Under the right pressure conditions, lowering the temperature of a substance in the gas state causes the
substance to liquefy. The opposite effect occurs if temperature is increased. - Under the right pressure conditions, lowering the temperature of a substance in the liquid state causes the
substance to solidify. The opposite effect occurs if the temperature is increased. - Pure substances have a constant composition and can only be changed by chemical reactions. They can be
classified as either elements or compounds. - Elements are substances that cannot be decomposed into simpler substances by chemical or physical means.
Compounds, however, can be broken down further through chemical, but not physical, means. - The periodic table is a tool that we use to help identify and describe the composition of a given substance. The
table is an arrangement of elements based on their physical and chemical properties. - Homogeneous or heterogeneous mixtures are formed when two or more pure substances are combined. A
homogeneous mixture has a uniform distribution throughout the sample, whereas a heterogeneous mixture
has visibly distinguishable components.