Ammonia gas decompses to form nitrogen and hydrogen gases. NH3(g) → N2(g) + 3H2(g) If the nitrogen gas is collected in a rigid 2 liter metal cylinder at 22oC at 2.00 X 103 kPa pressure, how many moles of nitrogen gas (N2) does the cylinder contain? A) 1.63 moles B) 1.35 X 10 moles C) 1.42 X 102 moles D) 1.82 X 102 moles

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.