chapter 8 (cont.)
DESCRIPTION
Chapter 8 (cont.). TYPES OF REACTIONS- patterns observed empirically allow prediction of products when reactants are known. SYNTHESIS. More complex product made from simpler substances General format : A + X → AX element + element → compound EX: Sodium + chlorine → - PowerPoint PPT PresentationTRANSCRIPT
Chapter 8 (cont.)
TYPES OF REACTIONS- patterns observed empirically allow prediction of products when reactants are known
SYNTHESIS More complex product made from simpler
substances General format : A + X → AX
element + element → compound EX:
Sodium + chlorine →
Magnesium + nitrogen →
Sodium + oxygen →
DECOMPOSITION A single reactant is broken down
into simpler substances AX → A + X
CMPD → ELEMENT + ELEMENT
Most require an input of energy to break the bonds in the reactants.
EX: water →
magnesium bromide →
SINGLE REPLACEMENT REACTIONS
An element on its own pushes another SIMILAR element out of a cmpd (replaces it)
An element can only be replaced by a more active element. Check activity series to decide if rxn will occur.
A + BX → AX + Belement + cmpd → different cmpd + diff. elem.
Ex: Al (s) + CuCl2 → OR: Y + BX → BY + X
Ex: Cl2 + NaBr →
Examples:
iron is added to a solution of silver nitrate (assume Fe3+)
A piece of sodium is dropped into water
Fluorine is bubbled into a solution of potassium iodide
Single Replacement (cont.)
More active metals get oxidized (give up electrons more easily to form positive ions), less active metals will accept them-get reduced LEO GER Atoms of uncombined elements have 0 oxidation
number. More active nonmetals gain electrons (get
reduced) more easily & form negative ions Reactions where e-’s are transferred can be
classified as oxidation-reduction or redox reactions.
DOUBLE REPLACEMENT REACTIONS
“IONS SWITCH PARTNERS” AX + BY → AY + BX
Cmpd + cmpd → two different compounds
1. Precipitation Rxns a) One product is soluble, the other is not
b) Use solubility rules to determine if there is a precipitate
EX: NaCl (aq) + AgCH3COO (aq) →
1. Precipitation Rxns (cont)
Ex: Solutions of barium nitrateand sodium sulfate are combined:
Solutions of lithium sulfate and magnesium bromide are combined.
2. Acid/Base Neutralization
Acid + base → salt + water
(H+) (OH-) nitric acid + lithium hydroxide →
sulfuric acid + potassium hydroxide →
Acetic acid + barium hydroxide →
Net Ionic Equations
1. Formula Unit Equation- normal balanced equation including states
(NH4)2S(aq) + Cd(NO 3)2 (aq) →2. Total Ionic Equation – all aqueous substances are
separated into ions. Note: polyatomic ions stay together as a group. Cancel all spectator ions
3. Net ionic equation- rewrite remaining equation w/states
Combustion Reactions Hydrocarbon + oxygen → carbon dioxide + water
CxHy + O2 → CO2 + H2O
Ex: Liquid decane, C10H22 , is burnt in air
Ammonium dichromate (Cr2O72-)
decomposes with heating into chromium (III) oxide, nitrogen, and water vapor.
White phosphorus (P4) ignites spontaneously in air to form solid tetraphosphorus decaoxide.
Ammonium nitrate is used as a fertilizer even though it can be explosive. It can be made by bubbling ammonia gas (NH3) through a solution of nitric acid.
An electric current is passed through a sodium chloride solution and forms sodium hydroxide, chlorine and hydrogen. The water in the solution participates in the reaction.