the student made 250 cm3 of a solution of citric acid of concentration o. o500 mol/dm 3 calculate the mass of citric acid required

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

what are the statements

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.