Common wisdom states that the Pyramids are 5,000 years old. But what proof do we have of that? There is a theory that states the pyramids are 35,000 years old. We are going to use chemistry to see how valid that assertion may be. What were the pyramids used for? What are they made out of? What are they located near? Chalk Limestone Marble What do chalk, limestone and marble have in common? Calcium Carbonate CaCO 3 Ca C O O O What happens when calcium carbonate (CaC0 3 ) is heated? CaO C0 2 Calcium Oxide Carbon Dioxide Calcium Carbonate heat Calcium Oxide + Carbon Dioxide CaCO 3 heat CaO + CO 2 (Quicklime) Thermal decomposition is the breakdown of a compound into smaller parts by heating. Ca O O H H What happens when calcium oxide is mixed with water? Ca(OH) 2 Calcium Hydroxide (Slaked Lime) Calcium Oxide + WaterCalcium Hydroxide CaO + H 2 0Ca(OH) 2 + (HEAT) Calcium hydroxide (slaked lime) when dissolved in water is known as limewater. Ca O H O H C O O CaCO 3 Calcium Carbonate H2OH2O Water Calcium Hydroxide + Carbon DioxideCalcium Carbonate + Water Ca(OH) 2 + CO 2 CaCO 3 + H 2 O All of this Chemistry is very useful but what does this have to do with the pyramids?? This is an explanation of the theory as drawn over a cup of coffee with a friend Pyramids Unexplained block in the pyramid Nile Chamber of CaO stalactites Underground Irrigation The chemistry part is concerned with the chamber underneath each pyramid: What would happen when water from the Nile reacts with the Calcium Oxide under the pyramids? CaO + H 2 O Ca(OH) 2 + HEAT What does all this suggest? Perhaps the pyramids were used a power stations If so, then how can they be 5,000 years old? The Nile has changed position of the millions of years that it has existed by the process of erosion: If the theory is correct then the Nile must have been here when the pyramids were built Scientists have calculated that for it to move to its present position took 35,000 years. These are the uses of the various compounds in the Limestone cycle: Limestone - CaCO 3 Quicklime - CaO Slaked Lime Ca(OH) 2 Limewater Ca(OH) 2 dissolved in water Building, sculptures, cement, neutralize acidic soil, roads, glass making, toothpaste, paper, paint, plastic, bread and cereal, cosmetics Portable food heating, cement, paper Water treatment, paper, mortar, brake pads Test for CO 2, clean SO 2, corn tortillas How do we obtain the CaCO 3 for all of these uses? Quarrying (digging it out of the ground) In pairs: discuss the advantages and disadvantages of a limestone quarry opening near your home