CHEM 120 Chapter Notes - Chapter 19: Nonmetal, Lead, Hydride

• School: McGill University
• Department: Chemistry
• Course: CHEM 120
• Professor: Laura Pavelka

Document Summary

Chapter 19: electrochemistry --chemical change and electrical work. If atom has higher oxidation number in product than had in reactant, then reactant contains atom was oxidized and is reducing agent: oxidation is shown by increase in oxidation number. If necessary, multiply one or both half-reactions by integer so that: number electrons gained in reduction = number lost in oxidation, add balanced half-reactions and include states of matter, check that atoms and charges balanced. Balancing redox reactions in acidic solution: for reaction in acidic solution, h2o and h+ ions present for balancing. 2- cr3+ and i- i2: divide into cr2o7, balance atoms & charges 14h+ + cr2o7. 2- 2cr3+ + 7h2o and 2i- i2. 3(2i- i2 + 2e-) = 6i- 3i2 + 6e: add half-reactions together: 6i- + 14h+ + cr2o72- 3i2 + 7h2o + 2cr3+ If use h3o+ instead of h+, only difference is in number of water molecules (increases)