The chemical reaction for CFC is: CCl3F = CCl2F + Cl. Uses. Due to their chemical properties, CFCs became useful as coolants and propellants. More commonly known as freon for refrigeration, CFCs are used extensively in appliances as a safe method of refrigeration. The other main use for CFCs has been as a propellant for aerosol cans.
The earliest known Egyptian pyramids are found at Saqqara, northwest of Memphis. The earliest among these is the Pyramid of Djoser (constructed 2630 BCâ2611 BC) which was built during the third dynasty. This pyramid and its surrounding complex were designed by the architect Imhotep, and are generally considered to be the world's oldest monumental structures constructed of dressed masonry.
DAY 2: Scale of the Structures. Build around 2560 B.C., the Great Pyramid of Giza is the last survivor of the Seven Wonders of the World, and until the early 20th century was the tallest building in the world. The Great Pyramid dominates the plateau of Giza. Students can get a sense of the scale and magnificence of the pyramids from virtual reality views available through Pyramids: The Inside Story and on Nova: Pyramids. Building the Great Pyramid was a huge task. Your students can learn about it by watching the flash animation at the British Museum's Ancient Egypt site.