Orange juice, Italian salad dressing, concrete, salt water and milk are all examples of mixtures. A mixture is defined as two or more pure substances that are mixed together while each substance is able to continue maintaining its own chemical properties.
Mixtures can be made of solids, liquids or gases; some mixtures can be composed of many different pure substances while others only need two different substances. A pure substance is something that has the same chemical properties no matter the temperature or other environmental factors that are present. Elements are the most common example of pure substances.
In order for a mixture to be considered a true mixture, it must be able to be separated out using only physical force. If chemicals are used to return the mixture to two separate entities, it is not considered a true mixture. Physical ways to separate mixtures include grinding and boiling. When specific physical changes happen to the mixture, it will return to its original state. The type of physical change that is needed for a mixture to be able to return to the original state the substances were in is dependent on the mixture and can vary according to environmental factors that include the temperature.