Unit 3 Flashcards
Solvent
The substance you have more of. (ex: water)
Solute
The substance you have less of. (ex: sodium)
Aqueous Solutions
Solutions in which water is the solvent.
Non-electrolytes
Do not dissociate in water and do not conduct electricity.
Weak-electrolytes
Some dissociation (low conductivity)
Strong-electrolytes
Strong acids - some dissociation (high conductivity)
Precipitation Reaction
Write balanced net ionic equation showing reactants and products.
Solubility Rules
Na+, K+, NH4+, NO3- are all soluble in water
Elemental Form Oxidation Rule
An atom in elemental form (Mg, Fe) = Oxidation number is 0
Mono-atomic Form Oxidation Rule
Oxidation number is equal to its charge (Mg2+ = +2) (Cl- = -1)
Hydrogen Oxidation Rule
+1 when bonded to nonmetal (in front), -1 when bonded to a metal (in back)
Electronegative Oxidation Rule
The most electronegative element has an oxidation number equal to its charge as an ion. (BF3, oxidation # for F=-1)
Determining Oxidation Numbers
Sum of oxidation numbers for all atoms in a compound must equal the overall charge of the compound (H2O, H=+2 O=-2, Overall = 0)
How to find what is oxidized and reduced?
Check oxidation numbers of products/reactants
How to structure reduction half reaction?
(ex: HClO3 + 3HNO2 -> KCl + 3HNO3) —–> KClO3 + 6e- -> KCl Oxidation changes from +5 to -1 so it gains 6e-
Activity Series
Au -> Pt -> Ag -> Cu -> Fe -> Zn -> Mg -> Ca -> Ba -> K (elements less easily oxidized will oxidize elements that are more easily oxidized)
Halogen Displacement Redox Reactions
Diatomic halogens that are bonded to themselves (ex: F2) can oxidize any ions below it in the family
Disproportionation Reactions
An element in one oxidation state undergoes both oxidation and reduction, must have an intermediate state.
Combustion Reactions
Always results in CO2(g) + H2O(l)
Acid Reactions
Acids donate protons in aqueous solutions, NO3- will oxidize metals that H+ cannot
Balancing REDOX Reactions in Acidic Solutions
1) Write two unbalanced half reactions
2) Balance all atoms except for O and H
3) Balance for O by adding H20
4) Balance for H by adding H+ ions
5) Balance charge by adding electrons
6) Cross multiply to cancel electrons
7) Add half reactions and cancel like terms
Common Reductions in Acidic Solutions
Nitrate (NO3-(aq) -> NO(g)
Permanganate (MnO4-(aq) -> Mn2+(aq))
Dichromate (Cr2O7-2(aq) -> Cr3+(aq))
All above oxidize p and d block metals, sulfite ions, peroxides, and substances w/ lower oxidation state than usual in acidic solutions.
Substances with Lower Oxidation States than Usual (ex. 1)
C2O4-2, Carbon has oxidations state of +3
It will oxidize to raise its oxidation state
Substances with Lower Oxidation States than Usual (ex. 2)
Some non-metals can raise their oxidation states by bonding with like elements
(Hydrochloric acid + species that is easily reduced)
What if two species can be oxidized?
When compounds have p block + d block metals and non metals the metal will be oxidized
Basic Solutions Concentrations
Basic solutions have a high concentration of hydroxide ions (OH-)
Redox Titrations
Solution w/ an unknown concentration of a species that will be oxidized in the reaction.
Equivalence Point
Occurs when equal numbers of moles of the species being oxidized and the species being reduced have combined.
