Common Types of Chemical Reactions

Decomposition

Double Displacement

Synthesis

Single Displacement

Combustion

Oxidation–Reduction Reactions A chemical reaction in which an atom or ion loses electrons to another atom or ion. Fe (s) + Al(NO 3 ) 3 (aq)  Fe(NO 3 ) 3 (aq) + Al (s) charges 003+ Fe: 0  +3 Oxidation Al: +3  0 Reduction Electrons Lost 3 Gained 3 “Redox” Reactions

Leo the Lion says, “Ger” OSEOSE LECTRONLECTRON XIDATIONXIDATION AINAIN LECTRONLECTRON EDUCTIONEDUCTION

Oxidation numbers (oxidation state) are a chemist’s way of keeping track of electrons. Assigning Oxidation Numbers

The convention is that the cation is written first in a formula, followed by the anion. For example, in NaH, the H is H-; in HCl, the H is H+. Assigning Oxidation Numbers

The oxidation number of a free element is always 0. The atoms in He and N 2, for example, have oxidation numbers of 0. Assigning Oxidation Numbers

The oxidation number of a monatomic ion equals the charge of the ion. For example, the oxidation number of Na + is +1; the oxidation number of N 3- is -3. Assigning Oxidation Numbers

The usual oxidation number of hydrogen is +1. The oxidation number of hydrogen is -1 in compounds containing elements that are less electronegative than hydrogen, (metals) as in CaH 2. Assigning Oxidation Numbers

The oxidation number of oxygen in compounds is usually -2. Exceptions include OF 2, since F is more electronegative than O and BaO 2, due to the structure of the peroxide ion, which is [O-O] 2- Assigning Oxidation Numbers

The oxidation number of a Group IA element in a compound is +1 Assigning Oxidation Numbers The oxidation number of a Group IIA element in a compound is +2 The oxidation number of a Group VIIA element in a compound is -1, except when that element is combined with one having a higher electronegativity. The oxidation number of Cl is -1 in HCl, but the oxidation number of Cl is +1 in HOCl.

The sum of the oxidation numbers of all of the atoms in a neutral compound is 0 CO 2 Na 2 CrO 4 C 2 H 5 OH Assigning Oxidation Numbers Carbon +4 Oxygen Sodium +1 Chromium +6 Oxygen Carbon -2 Hydrogen +1 Oxygen -2

The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion. For example, the sum of the oxidation numbers for SO 4 2- is -2. Assigning Oxidation Numbers PO 4 -3 NH 4 +1 ClO 3 -1 P 2 O 7 -4 P +5 O -2 N -3 H +1 Cl +5 O -2 P +5 O -2

Common Types of Chemical Reactions single displacement: A + BC  AC + B double displacement: AB + CD  AD + CB synthesis (formation): A + B  AB decomposition: AB  A + B combustion: C x H y + O 2  CO 2 + H 2 O oxidation-reduction (redox): (a large variety)

OXIDATION—the atom loses (an) electron(s); increase in oxidation number.OXIDATION—the atom loses (an) electron(s); increase in oxidation number. REDUCTION—gain of electron(s); decrease in oxidation number.REDUCTION—gain of electron(s); decrease in oxidation number. (an agent facilitates something; ex. Travel agents don’t travel, they facilitate travel) OXIDIZING AGENT—electron acceptor; species is reduced.OXIDIZING AGENT—electron acceptor; species is reduced. REDUCING AGENT—electron donor; species is oxidized.REDUCING AGENT—electron donor; species is oxidized. OXIDATION—the atom loses (an) electron(s); increase in oxidation number.OXIDATION—the atom loses (an) electron(s); increase in oxidation number. REDUCTION—gain of electron(s); decrease in oxidation number.REDUCTION—gain of electron(s); decrease in oxidation number. (an agent facilitates something; ex. Travel agents don’t travel, they facilitate travel) OXIDIZING AGENT—electron acceptor; species is reduced.OXIDIZING AGENT—electron acceptor; species is reduced. REDUCING AGENT—electron donor; species is oxidized.REDUCING AGENT—electron donor; species is oxidized. Redox Terms

How to balance complicated Redox reactions: (The simple ten step method!) 1)Assign oxidation numbers to each atom 2)Write the half reactions 3)Balance all atoms other than H and O (you may need to bring in species from the original equation) 4)Balance the O’s with H 2 O 5)Balance the H’s with H + 6)Balance the charges with e - 7)Multiply half reactions to make e - equal. 8)Add the half reactions. 9)Check your charges! If the solution is acidic, yer finished! If the solution is basic… 10)Add as many OH - to both sides as there are H +, then “simplify”.