Barrons SAT Subject Test Chemistry, 13th Edition

NaCl(aq) A water solution of dissolved sodium chloride

TIP

(g) = gaseous state

(ℓ) = liquid state

(s) = solid state

An example of phase notation in an equation:

2HCl(aq) + Zn(s) → ZnCl 2 (aq) + H 2 (g)

In words, this says that a water solution of hydrogen chloride (called
hydrochloric acid) reacts with solid zinc to produce zinc chloride dissolved in
water plus hydrogen gas.

WRITING IONIC EQUATIONS

At times, chemists choose to show only the substances that react in the chemical
action. These equations are called ionic equations because they stress the reaction
and production of ions. If we look at the preceding equation, we see the complete
cast of “actors”:

Writing the complete reaction using these results, we have:

2H+(aq) + 2Cl−(aq) + Zn(s) → Zn2+(aq) + 2Cl−(aq) + H 2 (g)

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In net ionic equations, do not show “spectator” ions that do not change.

Notice that nothing happened to the chloride ion. It appears the same on both
sides of the equation. It is referred to as a spectator ion. In writing the net ionic
equation, spectator ions are omitted, so the net ionic equation is: