CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
Two aqueous solutions are mixed. In the diagram’s initial frames, one beaker contains numerous red spheres labeled + (H+) along with pale-green spheres (Cl−). The second beaker contains blue spheres labeled + (Na+) together with small pairs of white spheres joined by a stick (OH−). In the final frame, only clusters of two white spheres joined together (H2O molecules) are shown along with free pale-green and blue spheres.
A student writes the net ionic equation as
H+(aq) + OH−(aq) → H2O(l).
Which of the following best explains why the Na+ ions, still visible in the final frame, do not appear in the student’s net ionic equation?
(a) They precipitate as solid NaCl and therefore are not shown in ionic form.
(b) Their concentration does not change during the reaction, so ions present in the larger excess are omitted from a net ionic equation.
(c) They are spectator ions that do not participate in bond formation or bond breaking during the reaction.
(d) Cations are never included in net ionic equations because charge balance is represented only with anions.