Need help with assigning oxidation numbers to elements in large compounds.

Test Preparation AP Test Preparation
1

<li>Assign oxidation numbers to all the atoms in each of the following.</li>
</ol>

<p>G. PbSO3</p>

<p>K. (NH4)2Ce(SO4)3</p>

2

<p>Ok im not going to bother with the second one because im lazy. For the first one you know that SO3 is a polyatomic ion with a charge of -2 (i believe?) and you know that O has a charge of -2. So from that we can get that S has a charge of +4. Pb has a charge of 2+ to balance out the 2- total charge of SO3 because the whole compound is neutral.</p>

3

<ol>
<li>Specify which of the following equations represent oxidation-reduction reactions, and indicate the oxidizing agent, the reducing agent, the species being oxidized, and the species being reduced.</li>
</ol>

<p>a. CH4 (g) + H2O (g) —> CO (g) + 3H2 (g)
oxidizing agent: H2O
reducing agent: CH4
species oxidized: C
species reduced: H</p>

<p>b. 2AgNO3 (aq) + Cu (s) —> Cu(NO3)2 (aq) + 2Ag (s)
oxidizing agent: AgNO3
reducing agent: Cu
species oxidized: Cu
species reduced: Ag</p>

<p>c. Zn (s) + 2HCl (aq) —> ZnCl2 (aq) + H2 (g)
oxidizing agent: HCl
reducing agent: Zn
species oxidized: Zn
species reduced: H</p>

<p>d. 2H+ (aq) + 2CrO4 2- (aq) —> Cr2O7 2- (aq) + H2O (l)
NOT A OXIDATION-REDUCTION REACTION</p>

<p>e. Cu (s) + 2Ag+ (aq) —> 2Ag (s) + Cu2+ (aq)
oxidizing agent: Ag+
reducing agent: Cu
species oxidized: Cu
species reduced: Ag+</p>