Question

Cr2O3(s) + 2Al(s) ---------> 2Cr(s) + Al2O3(s)

What loses electrons? ________  What gains electrons? ________  What is oxidized? ________  What is reduced? ________  What is the oxidizing agent? ________  What is the reducing agent? ________  Total electrons transferred per reaction cycle: ________

Answer 1

Oxidation states :

Cr₂O₃(s) + 2Al(s) ---------> 2Cr(s) + Al₂O₃(s)

+3 -2 0 0 +3 -2

Since oxidation state of Al change from 0 to +3,it implies Aluminum loses 3 electrons in the above equation.

Oxidation state of Cr change from +3 to 0 so Cr gains 3 electrons.

Oxidation is loss of electrons.so,Aluminum is oxidized here.

Reduction is gain of electrons.so,Chromium is reduced.

Oxidising agent is one which gains electrons and is reduced in a chemical reaction.So, Cr2O3 is the oxidizing agent.

Reducing agent is one which loses electrons and is oxidized in a chemical reaction.So,Al is the reducing agent.

Cr³⁺ + 3e^- -----> Cr(s)

Al(s) --------> Al³⁺  + 3e^-

^{so total electrons transferred per cycle = 3}