Activity Series & Redox Reactions Flashcards
Oxidation
The loss of 1 or more electrons by a substance
A- ——> A + electron
A ——> A+ + electron
Reduction
The gain of 1 or more electrons by a substance
A+ + electron ——> A
A + electron ——> A-
Oxidation number
Indicates whether an atom is neutral, electron-rich, or electron-poor
An atom in its elemental state has an oxidation # of…
0
An atom in a monotomic ion has an oxidation #…
Identical to its charge
Hydrogen has an oxidation # of…
(+1) or (-1)
Oxygen usually has an oxidation # of…
-2
Halogens usually have an oxidation # of…
-1
The sum of the oxidation numbers in a compound is…
- 0 for a neutral compound
- equal to net charge for poly atomic ion
*for finding charges of atoms your are unsure of
Redox reactions
Consist of two half reactions ( one oxidation, one reduction)
Reducing agent
- causes reduction
- loses 1 ore more electrons
- undergoes oxidation
- oxidation # increases
Oxidizing agent
- causes oxidation
- gains 1 or more electrons
- undergoes reduction
- oxidation # decreases
Generally, metals…
- are more cation-like
- have positive oxidation #’s
- are reducing agents
- lose electrons
Generally, nonmetals…
- are more anion-like
- have negative oxidation #’s
- are oxidizing agents
- gain electrons
Activity series
Ranks the elements in their ability to give up electrons (reducing ability) in aqueous solution
Fe (s) + Cu2+ (aq) ——> Fe2+ (aq) + Cu (s)
Iron gives up 2 electrons to copper
Iron reduces copper
React rapidly with H+ ions (acid) or liquid H2O to release H2 gas
-strongly reducing Li —> (Li+) + (e-) K—> (K+) + (e-) Ba—> (Ba2+) + (2e-) Ca—> (Ca2+) + (2e-) Na—> (Na+) + (e-)
React with H+ ions (acid) or steam to release H2 gas
Mg—>(Mg2+) + (2e-) Al—> (Al3+) + (3e-) Mn—> (Mn2+) + (2e-) Zn—> (Zn2+) + (2e-) Cr—> (Cr3+) + (3e-) Fe—> (Fe2+) + (2e-)
React with H+ ions (acid) to release H2 gas
Co—> (Co2+) + (2e-)
Ni—> (Ni2+) + (2e-)
Sn—> (Sn2+) + (2e-)
The position of hydrogen indicates which elements react with acid to release H2 gas
H2—> (2H+) + (2e-)
Do not react with H+ ions (acid) to release H2 gas
-weakly reducing Cu—> (Cu2+) + (2e-) Ag—> (Ag+) + (e-) Hg—> (Hg2+) + (2e-) Pt—> (Pt2+) + (2e-) Au—> (Au3+) + (3e-)
