5 Steps to a 5 AP Chemistry 2019

(^76) › STEP 4. Review the Knowledge You Need to Score High
Reactions will always appear in the free-response section of the AP Chemistry exam. This
may not be true in the multiple-choice part.
For the first two types, a table of metals relating their ease of oxidation to each other
is useful in being able to predict what displaces what. Table 6.1 shows the activity series
for metals, which lists the metal and its oxidation in order of decreasing ease of oxida-
tion. An alternative to the activity series is a table of half-cell potentials, as discussed in
Chapter 16, Electrochemistry. In general, the more active the metal, the lower its potential.
Elements on this activity series can displace ions of metals lower than themselves
on the list. If, for example, one placed a piece of tin metal into a solution containing
Cu(NO 3 ) 2 (aq), the Sn would replace the Cu^2 + cation:
+→+
+→+++
Sn(s)Cu(NO)(aq)Sn(NO)(aq)Cu(s)
Sn(s)Cu(aq)Sn(aq)Cu(s)
32 32
22
The second equation is the net ionic form that is often required on the AP exam.
If a piece of copper metal was placed in a solution of Sn(NO 3 ) 2 (aq), there would be no
reaction, since copper is lower than tin on the activity series. This table allows us to also pre-
dict that if sodium metal is placed in water, it will displace hydrogen, forming hydrogen gas:
+→ +
+→+−++
2Na(s) 2HO(l) 2NaOH(aq)H(g)
2Na(s) 2HO(l) 2Na(aq)2OH(aq) H(g)
22
22
Table 6.1 Activity Series of Metals in Aqueous Solution
Li(s) → Li+(aq) + e- Most easily oxidized
K(s) → K+(aq) + e-
Ba(s) → Ba^2 +(aq) + 2 e-
Sr(s) → Sr^2 +(aq) + 2 e-
Ca(s) → Ca^2 +(aq) + 2 e-
Na(s) → Na+(aq) + e-
Mg(s) → Mg^2 +(aq) + 2 e-
Al(s) → Al^3 +(aq) + 3 e-
Mn(s) → Mn^2 +(aq) + 2 e-
Zn(s) → Zn^2 +(aq) + 2 e-
Cr(s) → Cr^2 +(aq) + 2 e-
Fe(s) → Fe^2 +(aq) + 2 e-
Cd(s) → Cd^2 +(aq) + 2 e-
Co(s) → Co^2 +(aq) + 2 e-
V(s) → V^3 +(aq) + 3 e-
Ni(s) → Ni^2 +(aq) + 2 e-
Sn(s) → Sn^2 +(aq) + 2 e-
Pb(s) → Pb^2 +(aq) + 2 e-
H 2 (g) → 2 H+(aq) + 2 e-
Cu(s) → Cu^2 +(aq) + 2 e-
Ag(s) → Ag+(aq) + e-
Hg(l) → Hg^2 +(aq) + 2 e-
Pd(s) → Pd^2 +(aq) + 2 e-
Pt(s) → Pt^2 +(aq) + 2 e-
Au(s) → Au^3 +(aq) + 3 e- Least easily oxidized
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