Oxidation or Reduction?
What does OIL RIG stand for?
Oxidation Is Loss; Reduction Is Gain (of electrons)
What is the oxidation number of an element in its pure elemental form?
Zero.
How many electrons are lost in Zn --> Zn2+ + 2e-?
2 electrons
An atom loses 2 electrons. Is it oxidized or reduced?
Oxidized.
What is the oxidation number of oxygen in H2O?
-2
Balance __H2 + __O2 --> __H2O.
2H2 + O2 --> 2H2O
An element changes from +3 to +1. What process occurred?
Reduction; its oxidation number decreased.
What is the oxidation number of hydrogen in H2O?
+1
Write the reduction half-reaction for Cu2+ becoming Cu.
In Zn + Cu2+ --> Zn2+ + Cu, which species is the reducing agent?
Zn, because it loses e- and causes Cu2+ to be reduced.
+4
In 2Fe3+ + 6e- --> 2Fe, how many electrons are gained?
6 electrons.
In Fe2O3 + 3CO --> 2Fe + 3CO2, identify the oxidizing and reducing agents.
Fe2O3 is the oxidizing agent; CO is the reducing agent.
Determine the oxidation number of chromium in Cr2O72-?
+6
Balance the reaction: Fe2O3 + CO --> Fe + CO2.
Fe2O3 + 3CO --> 2Fe + 3CO2