An ionic substance is found to have the % composition by mass: 82% mercury, 4.9% carbon, and 13.1% oxygen. a. What is the empirical formula of the compound?

b. The molar mass of the compound is determined to be 489.2 g/mol. Determine the “molecular” formula of the compound.

i just learnt this recently but i need to look through my notes again

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.