Uma indústria possui dois cilindros idênticos, os quais estão nas mesmas condições de temperatura (27ºC) e pressão (1atm) e contêm o mesmo volume de gases, sendo que um está preenchido com gás hélio e o outro com gás neônio, ambos puros. Considerando que o cilindro com gás hélio tem 1,6 gramas desse gás, pela hipótese de Avogadro, o cilindro do gás neônio deverá conter, em gramas massa de gás igual a:

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.