Explain 1: Why do some ions interact with other in a reaction while others do not?
4. Consider the reactions that took place between the metals and hydrochloric acid.
Write a chemical equation of each reaction that took place. (Be sure to write each species
as it exists in solution) This is called the total ionic equation.
Ca(s) + 2HCl(aq) → CaCl
(aq) + H
(g)
2
2
+
-
2+
-
Ca(s) + 2H
(aq) + 2Cl
(aq) → Ca
(aq) + 2Cl
(aq) + H
(g)
2
No reaction for Copper and HCl
Mg(s) + 2HCl(aq) → MgCl
(aq) + H
(g)
2
2
+
-
2+
-
Mg(s) + 2H
(aq) + 2Cl
(aq) → Mg
(aq) + 2Cl
(aq) + H
(g)
2
Fe(s) + 2HCl(aq) → FeCl
(aq) + H
(g)
2
2
+
-
2+
-
Fe(s) + 2H
(aq) + 2Cl
(aq) → Fe
(aq) + 2Cl
(aq) + H
(g)
2
Sn(s) + 2HCl(aq) → SnCl
(aq) + H
(g)
2
2
+
-
2+
-
Sn(s) + 2H
(aq) + 2Cl
(aq) → Sn
(aq) + 2Cl
(aq) + H
(g)
2
Zn(s) + 2HCl(aq) → ZnCl
(aq) + H
(g)
2
2
+
-
2+
-
Zn(s) + 2H
(aq) + 2Cl
(aq) → Zn
(aq) + 2Cl
(aq) + H
(g)
2
5. When analyzing the reactions that took place, which ion(s) did not play an
“active” role in the reaction?
-
Cl
6. Using your answers from Problems 4 and 5, re-write this ionic equation, but
only include the species that play an active role in the change that occurs. Do this
for the reaction that occurs between magnesium and hydrochloric acid.
+
2+
Ca(s) + 2H
(aq) → Ca
(aq) + H
(g)
2
+
2+
Mg(s) + 2H
(aq) → Mg
(aq) + H
(g)
2
+
2+
Fe(s) + 2H
(aq) →Fe
(aq) + H
(g)
2
+
2+
Sn(s) + 2H
(aq) → Sn
(aq) + H
(g)
2
+
2+
Zn(s) + 2H
(aq) → Zn
(aq) + H
(g)
2
7. When these species are omitted, the net ionic equation is generated.
8. The ions that do not play a part in the reaction are called spectator ions.
These specie(s) can be removed from the total ionic equation to form the net ionic
equation (as you’ve done previously). If these ions do not play an active part
during the reaction, what is the purpose of them?
Spectator Ion – atom or group of atoms with a charge that is in both the
reactant and product side of the equation.
These ions are in solution to balance the charge of the solution.