Balance each reaction. Classify each reaction. Then decide if it is a REDOX reaction or not.
Classification Redox?
3.) _2__Al + __3_Cu(NO3)2 Cu + __2_Al(NO3)3 single replacement YES
4.) ___BaCl2 + ___Na2CrO4 BaCrO4 + __2_NaCl double replacement NO
5.) ___H3PO4 + _3__KOH H2O + ___K3PO4 neutralization (double replacement) NO
6.) ___CaCO3 ___CaO + ___CO2 decomposition NO
7.) ___N2 + _3__H2 _2__NH3 synthesis YES
8.) ___CH4 + ___O2 ___CO2 + ___H2O combustion YES
9.) A redox reaction is a reaction in which
only reduction occurs 3. reduction and oxidation occur at the same time
only oxidation occurs 4. reduction occurs first and then oxidation occurs
10.) Oxidation-reduction reactions occur because of the competition between particles for
neutrons 2. electrons 3. protons 4. ions
REHAB-Assignment #B: Redox Reaction Skill Drills (cont’d)
Skill #3 – Identifying Species Oxidized & Reduced (Text Reference: p. 633 – 634)
The element which is oxidized gains in oxidation number (becomes more positive)
The element which is reduced loses in oxidation number (becomes less positive).
Reduction (“G.E.R.”)
-5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5
Oxidation (“L.E.O.”)
Which change occurs when a Sn2+ ion is oxidized to Sn4+?
1. two electrons are lost 2. two electrons are gained 3. two protons are lost 4. two protons are gained
2.) When a substance is oxidized, it
1. loses protons. 2. gains protons. 3. loses electrons. 4. gains electrons.
3.) Given the reaction: Fe(s) + Sn4+(aq) Fe2+(aq) + Sn2+(aq)
The substance reduced is:
1. Fe(s) 2. Sn4+(aq) 3. Fe2+(aq) 4. Sn2+(aq)
4.) Given the reaction: 2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g )
Which substance undergoes oxidation?
1. Na 2. NaOH 3. H2 4. H2O
5.) In the reaction: Cu + 2Ag+ Cu2+ + 2Ag
The Cu atoms are oxidized when they lose 2 electrons.
(oxidized or reduced?) (gain or lose?) (how many?)
6.) In any redox reaction, the substance that undergoes reduction will gain (lose or gain?) electrons and as a result the value of the oxidation number will decrease (increase or decrease?).
REHAB-Assignment #B: Redox Reaction Skill Drills (cont’d)
7.) Given the reaction: Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2 (g)
Which statement correctly describes what occurs when this reaction takes place in a closed system?
Atoms of Zn(s) lose electrons and are oxidized. 3. There is a loss of mass.
Atoms of Zn(s) gain electrons and are reduced. 4. There is a gain of mass.
8.) Given the equation: C(s) + H2O(g ) CO(g) + H2(g)
Which species undergoes reduction?
1. C(s) 2. H+ 3. C2+ 4. H2(g)
9.) Given the reaction: Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)
Which particles must be transferred from one reactant to the other reactant?
1. ions 2. neutrons 3. protons 4. electrons
10.) Given the redox reaction: 2I-(aq) + Br2(l) 2Br-(aq) + I2(s)
What occurs during this reaction?
1. The I- ion is oxidized, and its oxidation number increases.
2. The I- ion is oxidized, and its oxidation number decreases.
3. The I- ion is reduced, and its oxidation number increases.
4. The I- ion is reduced, and its oxidation number decreases.
Potential Energy Diagram NOTES
Potential energy diagrams show conservation of energy!
Exothermic Example: S(s) + O 2 (g) SO 2 (g) + energy
High PE Low PE + heat
Total E before = Total E after
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