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77 Cards in this Set
- Front
- Back
Arrhenius acid |
Any compound that increases the concentration of H+ in aqueous solution |
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Arrhenius base |
Any compound that increases the concentration of OH- in aqueous solution |
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Common Arrhenius bases |
Group 1 and 2 cations |
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Acid-base reaction (aka neutralization) (with Arrhenius acids and bases) |
Arrhenius acid + Arrhenius base --> water + salt |
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Limitations of Arrhenius definition |
only applies in aqueous solution, but acids and bases can exist and react in the gas phase as well |
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pH |
-log[H+] |
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pOH |
-log[OH-] |
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[H+] |
10^(-pH) |
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[OH-] |
10^(-pOH) |
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pH + pOH = ? (for any aqueous solution at T = 25C) |
14 |
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The two properties of an acid solution that determine pH |
strength and concentration |
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strong acid/base |
one that dissociates completely in water |
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Bronsted-Lowry acid |
a species which is capable of donating a proton |
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Bronsted-Lowry base |
a species that is capable of accepting a proton, which requires a lone pair of electrons to bond to the H+ |
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amphoteric |
means "can act as an acid or as a base". usually used in reference to water. |
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Strong acids/bases ionize/dissociate _____ |
completely |
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Weak acids/bases ionize/dissociate _____ |
only partially |
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Conjugate base of a Bronsted-Lowry acid |
the species formed after the acid has donated its proton |
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Conjugate acid of a Bronsted-Lowry base |
the species formed after the base has accepted a proton |
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Common strong acids (there are 6 of them) |
HCl (hydrochloric acid) HBr (hydrobromic acid) HI (hydroiodic acid) H2SO4 (sulfuric acid) HNO3 (nitric acid) HClO4 (perchloric acid) |
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Common strong bases |
Group 1 and 2 hydroxides |
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Common weak bases |
neutral nitrogen-containing compounds, e.g. ammonia NH3 trimethylamine N(CH3)3 pyridine C5H5N |
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pKw at T = 25C |
14 |
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Kw at T = 25C |
1 x 10^(-14) |
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pKw in terms of pH and pOH |
pKw = pH + pOH |
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Kw in terms of [H3O+] and [OH-] |
Kw = [H3O+][OH-] |
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Number of mol of water in a liter |
56 |
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ratio of H3O+ (or OH-) ions to water molecules in any given volume of pure water |
1 to 560,000,000 |
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For what kinds of acids and bases is water's contribution of hydronium ions non-negligible |
weak acids and weak bases |
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Ka |
acid dissociation constant. equilibrium constant for the equation: HA + H2O --> A- + H3O+ |
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Ka in terms of [HA],[A-], [H3O+] |
Ka = [A-][H3O+]/[HA] |
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Kw in terms of Ka and Kb (only true for an acid and its conjugate base, or a base and its conjugate acid) |
Kw = Ka * Kb |
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Kb |
the base association constant. the analog of Ka but for bases. Equilibrium constant for the equation: B + H2O <-> HB+ + OH- |
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pKw in terms of pKa and pKb (only true for an acid and its conjugate base, or a base and its conjugate acid) |
pKw = pKa + pKb |
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A strong acid's conjugate base is ______ in water |
neutral |
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A weak acid's conjugate base is a ____ base A weak base's conjugate acid is a ____ acid |
1. weak 2. weak |
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For a strong acid, Ka ____ 1 |
Ka >> 1 |
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Equation for Kb |
Kb = [HB+][OH-]/[B] |
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When strong base reacts with weak acid, resulting solution is _____ |
basic |
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When strong acid reacts with weak base, resulting solution is _____ |
acidic |
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Effect of temperature on pKw |
As temperature increases, pKw decreases (i.e. Kw increases) |
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Why does gypsum appear to be more soluble in salt water than in fresh water? |
Background ions, or other ions, will tend to shield e.g. Ca2+ and SO4(2-) ions from each other. even more so if there are Cl- and Na+ ions, respectively, that can contribute even more to this effect. Therefore e.g. gypsum will appear to be more soluble in salt water than fresh water. |
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Correction for activity of free ion a_i |
ai = m_i * gamma_i m_i = mass fraction gamma_i = activity coefficient |
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Ionic Strength: what is the equation and what are the units? |
I = 1/2 sum_i (m_i * (z_i)^2) ...where _i refers to the ith ion ionic strength has concentration units |
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Hydration |
when an ion is surrounded and stabilized by water molecules |
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spectator ions |
ions that don't take part in a reaction (esp. a precipitation reaction) |
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formula for solubility product constant |
Ksp = [component 1] * [component 2] * ... * [component n] e.g. for salt: Ksp = [Na+][Cl-] |
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effect of pressure on solubility of a gas |
increase in pressure means increase of solubility for the gas |
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effect of pressure on solubility of solid or liquid |
no effect |
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true/false: pH affects solubility? |
true. (just be aware that it's all concentrations and equilibria, so think it through) |
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effect of ionic strength on solubility |
increase in ionic strength means decrease in solubility, since there are already a lot of ions in solution (presumably, this is subject to the assumption that some of the ions are the same as the ones already in solution?) |
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dissolution vs. solubility |
solubility is a thermodynamic concept dissolution is a kinetic concept |
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pH value range for most mineral-bearing waters |
6-9 |
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"H+ is important in all reactions associated with the formation, alteration (direction of reaction) and dissolution of _________" |
minerals |
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factors affecting pH in natural waters |
biological activities (photosynthesis, respiration) physical phenomena: aeration due to turbulence minerals (e.g. dissoln / precip of CaCO3, because it can increase or decrease CO2 conc.) oxygenation (often leads to decrease of pH) denitrification and sulfate reduction (often leads to decrease in CO2) |
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bases in natural waters |
Carbonate - CO3(2-) Bicarbonate - HCO3(-) Borate - B(OH)3 and its derivatives Phosphate - PO4(3-) Silicate - SO4(4-) Ammonia - NH3 Arsenate - AsO3(-) |
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acids in natural waters |
Sulfuric Acid - H2SO4 Nitric Acid - HNO3 Hydrochloric Acid - HCl Ammonium - NH4(+) Organic Acids |
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hydronium ion shape |
Trigonal Pyramidal |
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true or false: pH is affected by ionic strength |
true |
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density of seawater vs. freshwater at 25C, in g/cm3 |
seawater: 1.02 freshwater: 1.0029 |
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Freezing point of seawater vs. freshwater in deg C |
seawater: -1.91 freshwater: 0 |
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Surface tension of seawater vs. freshwater at 25C in dyne/cm |
seawater: 72.72 freshwater: 71.97 |
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water has a ______ boiling point and a _______ melting point |
1. high 2. high |
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definition of hydrogen bond |
electrostatic attraction that occurs between two polar molecules when a hydrogen bound to a highly electronegative atom such as N, F, or O experiences attraction to another highly electronegative atom |
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As temperature increases, hydrogen bonding _______ |
decreases |
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Explain the composite acid dissociation constant of H2CO3. |
CO2 dissolves from atmosphere into ocean. In ocean it hydrates to form H2CO3. [H2CO3] and [CO2(aq)] indistinguishable So we use a composite acid dissociation const, lumping the two quantities together. |
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pK(H2CO3) = ? |
3.8 |
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pK(H2CO3*) = ? (and why is it unusual?) |
6.3 high for such a strong acid, but that's because it's a composite constant for the dissolution AND hydration of CO2, but between those two forms it's only about 0.3% in the hydrated form |
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for H2CO3, the first (composite) dissociation constant H2CO3* = ? (and what's the easier approximation?) |
K1* = K(H2CO3) / (1 + K) but K is on the order of 650, so approximation: K1 ~ K(H2CO3) / K K: constant for hydration of CO2(aq) K(H2CO3): dissociation constant for H2CO3 itself |
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name the equations for all the K's in the reaction chain in the dissolution of CO2 into the ocean |
K = CO2(aq) / H2CO3 (hydration of CO2) K1 = [H+] [HCO3-] / [H2CO3*] K(H2CO3) = [H+] [HCO3-] / [H2CO3] ** K2 = [H+] [CO32-] / [HCO3-] Kw = [H+] [OH-] |
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Henry's Law |
P / Kh = concentration P = partial pressure Kh = a constant that depends on solute, solvent, and temperature concentration = concentration of gas in the liquid |
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Partial pressure |
Pressure x (that gas's mole fraction) |
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Young-Dupre equation |
W0 = gamma_lv (1 + cos a) gamma_lv = force between liquid and gas describes adhesion energy vs. contact angle |
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as contact angle decreases, adhesion ________ |
increases |
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interfacial energy of water and air (gamma_lv) |
72 mJ/m2 |
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surface energy |
the energy required to break the bond between molecules at the surface (interface) between two fluids. often expressed as gamma_(fluid1-fluid2) |
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Young's relation |
cos a = (sg - sl) / lg re: contact angle in terms of interfacial energies |