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What molecular geometry forms with 5 electron pairs (bonded and lone pairs) arranged about a central atom?
- e.g. Sulfur tetrafluoride
What are reactions in which a reactant is both oxidized and reduced?
2H2O2(aq) --> 2H2O(l) + O2(g)
Peroxide molecule (-1 oxidation state) separates into water (-2 oxidation state) and molecular oxygen (0 oxidation state).
What is a Brønsted–Lowry acid?
It is a species that can donate one or more protons.
What is a Lewis acid/base?
These are species that can accept an electron pair (acid) or donate an electron pair (base).
What equation is used to determine the pH of a buffer solution?
The Henderson-Hasselbach equation.
- A- = conjugate base
- HA = weak acid
- pKa = acid dissociation constant
What is the Rate Law equation?
For aA + bB ----> products
Rate = k[A]m [B]n
(in Molarity/unit time)
- k = rate constant (units vary with temp)
- m & n = reaction order
- A & B = concentrations (M)
m≠a & n≠b ***
At STP, what volume is occupied by the gas?
State the Dalton's Law of Partial Pressures.
1. The partial pressure of a gas is proportional to its mole fraction in the mixture.
PA = XAPtot where PA is the partial P of gas A (XA is its molar fraction)
2. The total P of a system is equal to the SUM of the partial Ps of the substances in the mixture.
3. The parital P of one gas in a mixture is independent of the other(s) in the mixture.
What is gamma decay?
It is a release of a photon from an element in a nuclear excited state (parent marked with a *), resulting in no change in charge, mass, or atomic number.
In what direction along the periodic table does elements' degree of electron affinity INCREASE?
To the right and up
along the periodic table.
- - Thus, F has the highest electron affinity.
- - Negative enthalpy (-ΔH) --> FAVORABLE!
Ideal Gas Law formula?
PV = nRT
Memory aid for naming polyatomic ions (oxyanions) with suffix -ate.
- First letter - main element
- Consonants - number of oxygens
- Vowels - number of negative charge
Solubility rules for soluble salts in aqueous solution.
1. All salts of alkali metal ions (e.g. Group IA elements --> Li, Na, K, Rb, Cs, Fr) are water-soluble.
2. All salts of ammonium (NH4+
) are water-soluble.
- 3. All salts with Cl-, Br-, I- are water soluble
- Except for salts containing Ag+, Pb2+, and Hg22+
- 4. All salts of SO42- (sulfate) ion are water soluble.
- Except for those containing Ca2+, Sr2+, Ba2+, and Pb2+
Solubility rules for insoluble salts in aqueous solution.
- 1. All metal oxides (a metal combined with oxygen) are insoluble,
- Except for:
- a) alkali metal oxides, and
- b) CaO, SrO, BaO <-- hydrolyze to form solutions of corresponding metal hydroxides.
- 2. All hydroxides (containing OH-) are insoluble,
- Except for:
- a) alkali metal hydroxides, and
- b) Ca(OH)2, Sr(OH)2, Ba(OH)2
- 3. All salts with the ff are insoluble:
- (1) carbonates (CO32-)
- (2) phosphates (PO43-)
- (3) sulfides (S2-)
- (4) sulfites (SO32-)
- Except for those containing:
- a) alkali metals, or
- b) ammonium (NH4+)
Rules for assigning oxidation numbers:
1. A free element (elemental state) has an oxid. number (O.N.) of 0
- 2. The oxidation number of a monoatomic ion equals charge of the ion.
- Ex. Na+, Cu2+, Fe3+, Cl-, N-3- --> +1, +2, +3, -1, -3 resp.
- 3. O.N. of a group IA element in a compound is +1;
- for group IIA elements in a compound, O.N. is +2.
- 4. O.N. of Group VIIA elements in a compound is -1;
- except: when combined with an element with higher electronegativity.
- ex. HCl: O.N. of Cl is -1
- HOCl: O.N. of Cl is +1 (oxid. state of oxygen is -2).
- 5. O.N. of H is +1 (most common);
- except: when combined with less-electronegative elements (Groups IA and IIA) --> O.N. is -1.
- ex: NaH and CaH2 (oxid. state of H is -1)
- 6. O.N. of oxygen is -2;
- except: when combined with a more electronegative element (e.g. OF2) --> O.N. of oxygen is +2 (F is more EN, thus has oxid. state of -1).
- ex. OF2 (oxid. state of F is -1), O.N. of oxygen is +2
- Peroxides (e.g. BaO2), O.N. of oxygen is -1 instead of -2 (Ba can't have oxid. state of +4)
- note: peroxide [O-O]-2 Ba2+
7. Sum of all O.N. of all atoms in a neutral compound is 0
8. Fluorine has O.N. of -1
in ALL compounds (F is most electronegative).
- 9. Metallic elements only have positive O.N.; however:
- non-metallic elements may have positive or negative O.N.
What is the Ideal Gas Law Constant?
- R = 0.0821 L·atm/mol·K
- R = 8.3145 J/mol·K
Units of pressure.
1 atm = 105 Pa = 760 mmHg = 760 Torr
Examples of strong acids:
- HClO4 (perchloric acid)
- HCl (hyrochloric acid)
- H2SO4 (sulfuric acid)
- HNO3 (nitric acid)
Examples of strong bases:
- NaOH (sodium hydroxide)
- KOH (potassium hydroxide)
- Ca(OH)2 (calcium hydroxide)
- other soluble hydroxides of group IA and IIA metals.