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Figure A is a photo of the flask containing a blue liquid. Several strands of brownish copper are immersed into the blue liquid. There is a brownish gas rising from the liquid and filling the upper part of the flask. Figure B shows a burning match. Figure C shows red meat being cooked in a pan. Figure D shows a small bunch of yellow bananas that have many black spots.
(a) Copper and nitric acid undergo a chemical change to form copper nitrate and brown, gaseous nitrogen dioxide. (b) During the combustion of a match, cellulose in the match and oxygen from the air undergo a chemical change to form carbon dioxide and water vapor. (c) Cooking red meat causes a number of chemical changes, including the oxidation of iron in myoglobin that results in the familiar red-to-brown color change. (d) A banana turning brown is a chemical change as new, darker (and less tasty) substances form. (credit b: modification of work by Jeff Turner; credit c: modification of work by Gloria Cabada-Leman; credit d: modification of work by Roberto Verzo)

Properties of matter fall into one of two categories. If the property depends on the amount of matter present, it is an extensive property    . The mass and volume of a substance are examples of extensive properties; for instance, a gallon of milk has a larger mass and volume than a cup of milk. The value of an extensive property is directly proportional to the amount of matter in question. If the property of a sample of matter does not depend on the amount of matter present, it is an intensive property    . Temperature is an example of an intensive property. If the gallon and cup of milk are each at 20 °C (room temperature), when they are combined, the temperature remains at 20 °C. As another example, consider the distinct but related properties of heat and temperature. A drop of hot cooking oil spattered on your arm causes brief, minor discomfort, whereas a pot of hot oil yields severe burns. Both the drop and the pot of oil are at the same temperature (an intensive property), but the pot clearly contains much more heat (extensive property).

Hazard diamond

You may have seen the symbol shown in [link] on containers of chemicals in a laboratory or workplace. Sometimes called a “fire diamond” or “hazard diamond,” this chemical hazard diamond provides valuable information that briefly summarizes the various dangers of which to be aware when working with a particular substance.

The diamond is subdivided into four smaller diamonds. The upper diamond is colored red and is associated with fire hazards. The numbers in the fire hazard diamond range from 0 to 4. As the numbers increase, the chemical’s flash point decreases. 0 indicates a substance that will not burn, 1 indicates a substance with a flashpoint above 200 degrees Fahrenheit, 2 indicates a substance with a flashpoint above 100 degrees Fahrenheit and not exceeding 200 degrees Fahrenheit, 3 indicates a substance with a flashpoint below 100 degrees Fahrenheit, and 4 indicates a substance with a flashpoint below 73 degrees Fahrenheit. The right-hand diamond is yellow and is associated with reactivity. The reactivity numbers range from 0 to 4. 0 indicates a stable chemical, 1 indicates a chemical that is unstable if heated, 2 indicates the possibility of a violent chemical change, 3 indicates that shock and heat may detonate the chemical and 4 indicates that the chemical may detonate. The lower diamond is white and is associated with specific hazards. These contain abbreviations that describe specific hazardous characteristic of the chemical. O X indicates an oxidizer, A C I D indicates an acid, A L K indicates an alkali, C O R indicates corrosive, a W with a line through it indicates use no water, and a symbol of a dot surrounded by three triangles indicates radioactive. The leftmost diamond is blue and is associated with health hazards. The numbers in the health hazard diamond range from 0 to 4. 0 indicates a normal material, 1 indicates slightly hazardous, 2 indicates hazardous, 3 indicates extreme danger, and 4 indicates deadly.
The National Fire Protection Agency (NFPA) hazard diamond summarizes the major hazards of a chemical substance.

The National Fire Protection Agency (NFPA) 704 Hazard Identification System was developed by NFPA to provide safety information about certain substances. The system details flammability, reactivity, health, and other hazards. Within the overall diamond symbol, the top (red) diamond specifies the level of fire hazard (temperature range for flash point). The blue (left) diamond indicates the level of health hazard. The yellow (right) diamond describes reactivity hazards, such as how readily the substance will undergo detonation or a violent chemical change. The white (bottom) diamond points out special hazards, such as if it is an oxidizer (which allows the substance to burn in the absence of air/oxygen), undergoes an unusual or dangerous reaction with water, is corrosive, acidic, alkaline, a biological hazard, radioactive, and so on. Each hazard is rated on a scale from 0 to 4, with 0 being no hazard and 4 being extremely hazardous.

Practice Key Terms 6

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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