Test 4 Content Overview This Is Not Necessarily a Complete List Content that we are building upon Chapter 14 Equilibrium constant expression Q K system at equil Q K reaction proceeds to the right until reaches equil generate more products consume more reactants Q K reaction proceeds to the left until reaches equil Consume more products generate more reactants Predict the final concentration at equilibrium ICE Method Solid and liquids not included in Q K Multiple equilibria K overall k1 k2 k3 not equation sheet Kc K c K c on Kforward vs Kreverse K 1 favor product formation Kfwd Krev K 1 favor reactant formation Kfwd Krev Reaction quotient function of the concentrations or pressures of the chemical species involved in a chem reaction Q products m reactants n at any time Concentrations used in Q not necessarily equilibrium values help predict how the equilibrium will respond to an applied stress A0 Kc 400 approximation get rid of X 400 keep X Le Ch telier s Principle System becomes out of equilibrium it will react and return Factors that can affect Equilibrium Concentration no effect on K R always left P always right positive charge than the corecponding acid ex HCL Cl Autoionization of Water Kw dissociation of a pure liquid self ionization weak electrolyte acts as an acid and base water ion product constant of water pH and pOH Strong Weak Acids Strong Acids completely break up into their iones changing solids and liquids does not influence equilibrium Chapter 15 Bronsted Acid Base Acid substance that donates H Base substance that accepts H Have a lone pair of electrons Conjugate Acid Base Pairs an acid and a base react to form their conjugate base and conjugate acid respectively conjugate acid base with a proton added H ex HS H2S Conjugate base always has one less H atom and one more negative or Kb up Base strength up Kw KaKb Polyprotic Acids Ka1 Ka2 etc May yield more than one hydrogen molecule ionize in stepwise manner loose one proton at a time Weak acids only partially break up into ions don t completely dissociate they go to equilibrium Strong Weak Bases Strong bases completely break up into their ions Weak bases only partially break into ions don t completely dissociate go to equilibrium Acid ionization constant Ka Ka up acid strength up Base ionization constant Kb Ka1 Ka2 Ka3 etc Acid Base Properties of Salts Stronger base larger Kb weaker base smaller kb New content Chapter 16 Common Ion Effect The shift in equilibrium caused by the addition of a compound having an ion in common with the dissolved substance use equation below Henderson Hasselbalch Equation pKa pKa log Ka Buffers Solution containing a weak acid weak base and the salt of the weak conjugate base or weak acid Ex KNO2 HNO2 NH3 NH4NO3 Buffer Capacity its ability to resist pH The more concentrated the components of a buffer the greater the buffer capacity Also has a high capacity when the component are equal pH pKa highest buffer capacity the addition of a strong acid or base weakens buffer capacity concentrations Ex PH given concentrations using pH pKa log conj base acid Ka 5 6 10 10 Ex Ratios Ph of bicarbonate is 8 calcualte the ratio of H2CO3 to that of HCO3 find pKa using Ka the equation into pH pKa log conj base acid then plug Buffer response to strong acid base Acid base titrations Titration a solution of accurately known concentration is gradually added to another solution of unkown concentration until the chemical reaction between the solutions is complete Acid base titration a neutralization process aimed at adding a necessary amount of acid H or base OH to a solution of bas acid in order to reach the equivalence point Moonoprotic acids Convert solution volume to mL then divide by its concentration and then that divided by the grams given Ex Equivalence point the number of moles of added H3O or OH ions equals the number of moles of OH or H3O ions originally present Buffer region Indicators Substance that changes colr with respect to H Indicator selection Add an acid H equilibrium shifts left Remove an acid H equilibrium shifts right Key to useful indicator is having the color change near the equivalence point Solubility equilibria Solubility product constant Ksp The smaller the solubility product the less soluable is the salt The larger the solubility product the more soluble is the salt If two compunds have the same ion ratio the one with the larger Ksp will have the higher molar solubility Ksp goes up Solubility goes up Molar solubility mol L mol L number of moles of solute dissolved in 1 L of a saturated solution Solubility g L is the number of grams of solute dissolved in 1 L of a saturated solution Conversion Ksp to M to g L Ksp and Molar solubility Ksp indicates solubility of an ionic cpd the smaller the value of Ksp the less soluable it is in water Ion pair formation and salt hydrolysis decrease the concentrations of the ions that appear in the Ksp expression Q vs Ksp Fractional Precipitation a method of precipitating some ions from solution while leaving others in solution Common Ion effect and solubility presence of a common ion decreases the solubility of the salt pH and solubility insoluble bases dissolve in acidic solutions insoluble acids dissolve in basic solutions If the conjugate acid is strong then the solution is not soluble in an acidic solution Larger Kf indicates that the complex ion is stable Dissociation constant Kd eqiuilibrium constant for dissociation complex Kd 1 Kf Ksp vs Kf K Kspx Kf Sea Shells and Sink Holes Complex ions an ion contining a central metal cation bonded to one or more molecular ions Metal ions lewis acid especially transition metals form coordinate covalent bonds with molecules or anions havinf a lone pair of electron bas lewis base Ligand lewis bases that bonds to a metal ion to form a complex ion Complex ion equilibria Formation constant Kf equilibrium constant for the formation of a complex ion Solubility and Photography 2 The developer converts the latent image to macroscopic particles of metallic silver 3 A stop bath typically a dilute solution of acetic acid or citric acid halts the action of the developer A rinse with clean water may be substituted 4 The fixer makes the fixer image permanent and light resistant by dissolving remaining silver halide A common is hypo specifically ammonium thiosulfate Washing in clean water removes any remaining fixer Residual fixer can corrode the silver image leading to discolouration staining and fading Qualitative
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