Question

Chemical reactions

a) simply change the atom or state of the reactants

b) create new atoms

c) always produce new substance

d) create more matter than what they started with

Answer 1

A chemical reaction or a chemical change is defined as a process by which the ionic or molecular structure of a substance changes resulting from the breaking and formation of chemical bonds or forces of attraction. For instance, the reaction of the reaction between an acid HCl and a base NaOH results in the formation of NaCl and H₂O. The Na-O bond and the H-Cl bond in the reactants are missing in the products and Na-Cl and H-OH bonds are formed.
Upon analysing the statements given, one can clearly figure out that statement (d) is wrong as all chemical changes occur by the law of conservation of mass and energy. Hence, a chemical reaction simply cannot create more matter than it started with.
A chemical reaction does not create new atoms but simply breaks and forms bonds resulting in the formation of new molecules. Hence, statement (b) is also incorrect. Any process that simply changes the state of the reactants is defined as a physical change and not a chemical change. Hence, the statement (a) is also incorrect.

However, the statement (c) is applicable to a chemical reaction as it does result in the formation of new substance; i.e., products are always distinct from reactants.