Amazon rubber boom the expansion of Iquitos in Peru. The rubber boom occurred largely between 1879 and 1912. There was heightened rubber production and associated activities from 1942 to 1945 during the Second World War. Natural rubber is an elastomer, also known as tree gum, India rubber, and "caoutchouc," which comes from the rubber tree in tropical regions. Christopher Columbus was the one of the first Europeans to bring news of this odd substance back to Europe, but he was not the only one to report it. Around 1736, a French astronomer recalled how Amerindians used rubber to waterproof shoes and cloaks. He
Amount of substance are atoms in of the isotope carbon-12. This number is called the Avogadro number and has the value It is the numerical value of the Avogadro constant, which has the unit mol, and relates the molar mass of an amount of substance to its mass. Therefore, the amount of substance of a sample is calculated as the sample mass divided by the molar mass of the substance. Amount of substance appears in thermodynamic relations such as the ideal gas law, and in stoichiometric relations between reacting molecules as in the law of multiple proportions. Another unit of amount of substance