During a chemical reaction, methane (CH,) and oxygen (0.) combine to produce carbon dioxide (CO) and water (H2O). The
balanced chemical equation identifies the reactants and products for
this reaction along with some of their masses. What mass (in grams)
of oxygen (O2) is required for this reaction to occur?
A.16
B. 36
C.44
D. 64

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error

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.