CHM2 Final

In general, why can't you use stoichiometric coefficients to determine rate laws?

A balanced chemical equation tells nothing, in general, about how a reaction occurs (i.e. mechanism of reaction).

True or false: Kp is always greater than Kc.

False

True or false: The equilibrium constant for the autoionization of water, Kw, is always 1.0E-14 no matter what the experimental conditions.

False

True or false: Two reactions with identical activation energies will always have the same rate constant as long as the reactions are run at the same temperature.

False

Which ion would you expect to produce a more acidic aqueous solution: Fe2+ or Fe3+?

Fe3+

If the partial pressure of CO2 in the atmosphere doubles in the next few decades, the dissolved CO2 in the oceans would also double, assuming a constant temperature (see extra credit question). -What would happen to the pH of the oceans (increase/decrease)?

decrease

Car antifreeze contains 8 L of water and 2 L of methanol (0.8 g/mL). What is the lowest operating temperature of the car using this antifreeze? Kf = 1.86°C/m. MM of methanol = 32.04-g

-11.6C

A certain aqueous solution has a normal boiling point of 101.70 degreesC. At what temperature would you expect this same solution to freeze under standard conditions? Kf = 1.86C/m Kb = 0.52C/m How many grams of ethylene glycol must be added to 100-g of water to produce such a solution? MM of EG = 62.07 g/mol

-6.08C Use DeltaTb to solve for m. Use that m to solve for DeltaTf. 20.23-g

Ethylene glycol (EG) is a common automobile antifreeze. It is water soluble and fairly nonvolatile. Calculate the freezing point of a solution containing 651-g of this substance in 2505-g water. The molar mass of ethylene glycol is 62.07-g. Kf=1.86C/m

-7.79 degreesC Use DeltaT = km DeltaT = Tf(pure) - Tf

What does Delta n have to equal in order to solve for Kp and make Kc=Kp?

0

What is the equilibrium concentration of [H+] in a 0.10M aqueous lactic acid solution? pKa of lactic acid = 3.85

0.00369 M

Calculate the mass of BaCl2 required to prepare 1 kg of a 3% by mass aqueous solution. What will be the molarity of this solution, assuming a solution density of 1 g/mL? MM of BaCl2 = 208.2-g

0.03 kg; 0.1444 M For molarity: Remember that 0.03kg/1kg is the same as 0.03g/1g.

The normal boiling point of dimethylformamide is 153°C. A student is trying to boil off this solvent under reduced pressure in a vacuum apparatus. What pressure must the student achieve if the maximum temperature attainable in his device is 90°C. The enthalpy of vaporization is ΔHvap = 42.25 kJ/mol for dimethylformamide.

0.126 atm Use CC equation.

The average osmotic pressure of seawater is about 30.0 atm at 25 degreesC. Calculate the molar concentration of an aqueous solution of sucrose that is isotonic with seawater.

1.23M pi = MRT

Calculate the molality of a sulfuric acid solution containing 24.4-g of sulfuric acid in 198-g of water. The molar mass of sulfuric acid is 98.09-g.

1.26 m

The pH of a 0.025 M solution of butanoic acid, C3H7COOH, is 3.21. What is the value of the ionization constant for this acid?

1.56E-5

A sample of 0.892-g of KCl is dissolved in 54.6-g of water. What is the percent by mass of KCl in the solution?

1.61%

The osmotic pressure of a 0.010 M KI solution at 25C is 0.465 atm. Calculate the van't Hoff factor for KI at this concentration.

1.90

Find the boiling point for a solution obtained by dissolving 6.58 g of sugar (C12H22O11) in 200 mL of water. Kb = 0.516°C/m. MM of sugar = 342.3 g/mol

100.05C

Determine the boiling point of a solution of 2 g of NaOH in 100 mL of water. Assume complete dissociation of NaOH. Kb = 0.516°C/m. MM of NaOH = 40 g/mol

100.5C *Complete dissociation of NaOH means i = 2.

What is the pOH of a 0.10 M solution of lactic acid at 25C? [H+] = 0.00369 M

11.57

A 1998 "Science Watch" article in the NYT offers an alternative to storing your valuable documents in a safe deposit box: store them in a refrigerator. The argument is that a 36 degree drop in temperature from 77F to 41F (25C to 5C) slows the breakdown of cellulose and starch, common elements of paper, by a factor of 40. According to this information, what is the activation energy for the breakdown process?

127 kJ/mol

Calculate the molality of a 2.50 M NaCl solution (density of solution = 1.08 g/mL) molar mass of NaCl = 58.44 g/mol

2.68 M Change density to 1080 g/L; solve moles of NaCl from Molarity; convert moles of NaCl to grams; subtract from solution grams to find kg of solvent.

The density of a 2.45 M aqueous solution of methanol is 0.976 g/mL. What is the molality of the solution? The molar mass of methanol is 32.04-g.

2.73 m Convert density to g/L. Find how many grams of methanol are in 2.45 moles of the 1 Liter solution, and subtract that gram amount from solution gram amount to solve for kg of solvent.

A 10% by mass aqueous solution of hydrogen chloride has a density of 1.046 g/mL. What is the molarity of the solution? MM of HCl = 36.46-g

2.87 M

In a 0.0100 M aqueous solution of methylamine, CH3NH2, the equilibrium concentrations of the species are [CH3NH2] = 0.0080 mol/L and [CH3NH3+] = [OH-] = 0.0020 mol/L. Calculate pKb for this weak base.

3.30

What is the pH of a solution that is 0.11 M in nitrous acid, HNO2, and 0.15 M in sodium nitrite (NaNO2)? What is the pH after 0.14 mol of NaOH has been added to 1.0 liter of the solution. (pKa=3.347)

3.48 12.47

Calculate the vapor pressure of a solution made by dissolving 218-g of glucose (molar mass = 180.2 g/mol) in 460 mL of water at 30 degreesC. What is the vapor-pressure lowering? Vapor pressure of pure water at 30C = 31.82 mmHg

30.4 mmHg 1.4 mmHg Use Raoult's Law: P1 = (X1)(P1pure) *Raoult's Law strictly deals with solvent.

Calculate the amount of water (g) that must be added to 5-g of urea in the preparation of a 16.2 percent by mass solution.

30.86-g

Determine the final state and its temperature when 150 kJ of heat are added to 50 g of water at 20 degrees C. The specific heat of steam is 1.99 J/gC. specific heat of water = 4.18 J/gC DeltaH(vap) = 40.79 kJ/mol

304 degrees C (302.4) Find heat needed to raise water from 20 to 100C. Subtract that value from 150 kJ. Use q=nDeltaH to multiply moles by DeltaH. Subtract that value from heat in first step. Use that value as q in: q=msDeltaT and use specific heat of steam and (T-100) for DeltaT.

The vapor pressure of water at 25°C equals 3166 Pa. Determine the vapor pressure of a solution of 10 g of carbamide, CO(NH2)2, in 1 L of water. MM of carbamide = 60-g/mol

3156.5 Pa Use P(H20) = X(H20) + Pknot(H20)

The vapor pressure of benzene, C6H6 is 40.1 mmHg at 7.6 degrees C. What is its vapor pressure at 60.6 degrees C? The molar heat of vaporization of benzene is 31.0 kJ/mol.

331 mmHg Use CC equation to solve for P2.

What is the boiling point atop Mt. Whitney where the atmospheric pressure is roughly 440 Torr. The molar enthalpy of vaporization of water, DeltaH(vap) = 40.7 kJ/mol

358 K... 85.1C Use CC Equation and 1 atm and 25C as T-P pair

Determine the molar mass of an organic compound, if a 500-mL solution that contains 11.5 g of this compound exhibits osmotic pressure of 1218 kPa at 25°C.

46.79 g/mol

The molar heats of fusion and sublimation of molecular iodine are 15.27 kJ/mol and 62.30 kJ/mol, respectively. Estimate the molar heat of vaporization of liquid iodine.

47.03 kJ/mol Draw graph of phase change and see that it makes sense to subtract.

The average rate constant for acetaminophen is 0.32 hr^-1. Assuming an initial dose of 20 g, how long would it take to reduce the amount of acetaminophen in the body to 4g?

5.03 hr ln[A]=-kRt+ln[A(initial)]

The solubility of nitrogen gas at 25 degreesC and 1 atm is 6.8E-4 mol/L. What is the concentration (M) of nitrogen dissolved in water under atmospheric conditions? The partial pressure of nitrogen gas in the atmosphere is 0.78 atm.

5.3E-4 M Use Henry's Law: c = kP Solve for k with info at STP. Use your Henry's Law constant to solve for C at given pressure.

Calculate the molality of a 35.4 percent (by mass) aqueous solution of phosphoric acid. The molar mass of phosphoric acid is 97.99 g.

5.59 m

The vapor pressure of water at 40°C equals 55.3 torr. Determine the vapor pressure of a 4% by mass solution of glucose (C6H12O6) in water. MM glucose = 180 g/mol

54.99 torr Use P(H20) = X(H20) + Pknot(H20)

The solubility product for calcium carbonate is 4.8E-3. What is the solubility of calcium carbonate in grams per liter of solution? (MM of CaCO3= 100.09g/mol)

6.9 g/L

The standard enthalpy of formation of gaseous molecular iodine is 62.4 kJ/mol. Use this information to calculate the molar heat of sublimation of molecular iodine at 25 degrees C.

62.4 kJ/mol DeltaH(sublimation) = DeltaH(formation)+DeltaH(vaporization) Since DeltaH for molecular iodine at 25 degreesC is molecular iodine at its standard state, DeltaH for this process is 0.

Diethyl ether is a volatile, highly flammable organic liquid that is used mainly as a solvent. The vapor pressure of diethyl ether is 401 mmHg at 18 degrees C. Calculate its vapor pressure at 32 degrees C.

656 mmHg Hint: Use CC Equation to solve for P2.

A solution is prepared by dissolving 35.0-g of hemoglobin (Hb) in enough water to make up 1-L in volume. If the osmotic pressure of the solution is found to be 10.0 mmHg at 25 degreesC, calculate the molar mass of hemoglobin.

65789.47 g/mol Use osmotic pressure formula to solve for M and moles; then put solution gram amount over moles.

A 1.20-g sample of water is injected into an evacuated 5.00-L flask at 65 degreesC. What percentage of the water will be vapor when the system reaches equilibrium? Assume ideal behavior of water vapor and that the volume of liquid water is negligible. The vapor pressure of water at 65 degreesC is 187.5 mmHg.

66.8% Use PV=nRT to find mole amount at equilibrium. Convert water in grams to water in moles. Use that value in comparison with equilibrium value to find percentage.

What is the vapor pressure of mercury at its normal boiling point (357 degrees C)?

760 mmHg Normal boiling point is at 1 atm.

200 mL of a 3 M aqueous solution of Na2SO4 was evaporated to dryness. What is the mass of the solid obtained? What was the mass percent concentration and mole fraction of Na2SO4 in the original solution, assuming a solution density of 1 g/mL? MM of Na2SO4 = 142.04 g/mol

85.2-g Na2SO4; 0.086 Remember that mole fraction should look like: 0.094/(0.094+1)

A solution of 3.2 g of methanol (CH3OH) in 1 L of water exhibits the same osmotic pressure as a solution of aniline (C6H5NH2). What mass of aniline is contained in 1 L of the solution? MM of methanol = 32-g MM of aniline = 93.12-g

9.3 g

The equilibrium vapor pressure of water at 15C is 12.8 Torr with a liquid density of approximately 1.00-g/mL. 10.0 mL of water is left to evaporate inside a 5.00-L container at 15C. What volume of liquid, if any, remains in the flask? Assume there is no water vapor initially in the container as a closed thermodynamic system.

9.94 mL *Make sure to convert mole amount back to mL of water.

Calculate the amount of energy (in kJ) to heat 346 g of liquid water from 0 degrees C to 182 degrees C. Assume that the specific heat of water is 4.184 J/gC over the entire liquid range and that the specific heat of steam is 1.99 J/gC. Delta Hvap = 40.79 kJ/mol

985 kJ Hint: Heat water from 0 to 100; evaporate 346 g of water at 100 degrees C; heat steam from 100 degrees C to 182 degrees C. q=msDeltaT q=nDeltaH

The following gas-phase decomposition reaction is first-order: C2H5Cl → C2H4 + HCl The activation energy for this reaction Ea = 237 kJ/mol and the Arrhenius frequency factor, A, is 1.58·1013 s-1. Calculate the value of the specific rate constant at 25°C and 275°C.

@25C: 4.74E-29 sec^-1 @275C: 4.11E-10 sec^-1

Consider two solutions that contain equal concentrations of NaCl and Cl2. In which case do you expect a larger change in the boiling and freezing points of the solution? Explain.

Boiling point and freezing point are colligative properties that only depend on the amount of solute present. Cl2 would have a VH factor of 1 and NaCl would have a VH factor of 2... The NaCl would have a greater change. *Remember VH factor is # of things after dissociation.

What are the 6 strong acids?

HCl, HBr, HI, HNO3, HClO4, H2SO4

A mixture of 3.00 mol of Cl2 and 3.00 mol of CO is enclosed in a 5.00 L flask at 600°C: CO(g) + Cl2(g) ⇄ COCl2(g) At equilibrium, 3.3% of Cl2 has been consumed. Calculate Kc and Kp for this reaction.

Kc = 0.0588 Kp = 8.2E-4

A 7.85-g sample of a compound with the empirical formula C5H4 is dissolved in 301-g of benzene. The freezing point of the solution is 1.05 degreesC below that of pure benzene. What are the molar mass and molecular formula of this compound? Molar mass of C5H4= 64 g/mol Kf=5.12C/m

Molar mass = 128.69 g/mol C10H8

California's highest elevation point is Mt. Whitney (4,400 m above sea level) and its lowest point is in Death Valley (282 m below sea level). At which location would you expect water to boil at a lower temperature?

Mt. Whitney

Which is a stronger base: NO2- or NO3-?

NO2-

Will a precipitate of PbCl2 form when 5.0 g of solid Pb(NO3)2 is added to 1.00 L of 0.010 M NaCl? Assume that volume change is negligible. MM of Pb(NO3)2= 331 g/mol Ksp of PbCl2= 2.4E-4

No solid precipitate Q<Ksp

For the decomposition of O3(g) to O2(g), ΔH0 = -285.4 kJ/mol and ΔS0 = 137.55 J/mol·K at 25°C. Are the reactants (O3) or products (O2) favored at this temperature? Is (are) either or both of the driving forces (enthalpy and entropy changes) for the reaction favorable?

Products favored. Both enthalpy and entropy changes are favorable.

Consider the ionization of formic acid, HCOOH: HCOOH (aq) + H2O (l) ⇄ HCOO- (aq) + H3O+ (aq) Explain what effect the addition of sodium formate, NaHCOO, has on the fraction of formic acid molecules that undergo ionization in aqueous solution?

Shift left; smaller fraction of HCOOH will dissociate.

Write the solubility product expression for each of the following salts: a. MgF2 b. CuCO3 c. Bi2(SO4)3 d. Ag3PO4

a) Ksp= [Mg2+][F-]^2 b) Ksp= [Cu2+][CO3 2-] c) Ksp= [Bi3+]^2[SO4 2-]^3 d) Ksp= [Ag+]^3[PO4 3-]

What is the relationship between acid strength and the value of Ka?

Stronger acid = larger Ka

What is the relationship between base strength and the value of pKb?

Stronger base = smaller pKb

What factor affects Kc?

Temperature

Determine mole fractions of water and sodium hydroxide in 16% by mass solution of NaOH. MM of NaOH = 39.997g/mol

X(NaOH) = 0.079 X(H2O) = 0.92

The equilibrium constant Kc for the reaction, Br2(g) + F2(g) ⇄2BrF(g), is 55.3. What are the equilibrium concentrations of all the gases if the initial concentrations of bromine and fluorine were both 0.180 mol/L? What is the equilibrium constant Kp?

[Br2] = 0.038M [F2] = 0.038M [BrF] = 0.284M Kp= Kc (because Delta(n) = 0!)

Calculate the concentration of all the species present in a 0.42 M benzoic acid solution. (Ka = 6.3·10-5)

[H+] = 0.005M [C6H5COO-] = 0.005M [C6H5COOH] = 0.415M

For the reaction described by the equation N2(g) + C2H2(g) ⇄ 2HCN(g), Kc = 10 at 300°C. Find the equilibrium concentrations and partial pressures of all gases if the initial concentrations of N2 and acetylene (C2H2) were 3.3 mol/L and 2.0 mol/L, respectively.

[N2] = 1.8M [C2H2] = 0.5M [HCN]= 3.0M P(N2) = 84.7 atm P(C2H2) = 23.6 atm P(HCN) = 141 atm

Suppose you prepare a [HCOOH]:[NaHCOO] buffer with a pH of 3.45. a. If 1.00 L of your solution contains 1.00 mole of HCOOH, how many moles of NaHCOO are present in the solution? The Ka of HCOOH is 1.77x10-4. b. If you add 0.10 moles of HCl to 1.00 L of this solution, what is the resulting pH? Assume no volume change upon addition of the HCl.

a) 0.5 mol b) 3.3

Calculate the pH of the following solutions: (a) 2.00·10-1 M HCl; (b) 0.050 M HNO3; (c) 0.65 g/L HClO4.

a) 0.699 b) 1.3 c) 2.19

Carbon dioxide reacts with hot carbon in the form of graphite producing carbon monoxide. The equilibrium constant for the reaction Kc = 10.0 at 850°C. 25.0 g of carbon dioxide is placed in a 2.5-L reaction vessel and heated to 850°C. Determine: a. The mass of carbon dioxide at equilibrium. b. The total pressure in the vessel? c. The equilibrium constant Kp. MM of CO2= 44.01 g/mol

a) 1.98 g b) 40.2 atm c) 893

A(g) + 3B(g) ⇄ 2C(g) + 3D(g) a. At equilibrium, a 4.00 L vessel was found to contain 1.60 moles of C, 1.60 moles of D, 0.40 moles of A, and 0.40 moles of B. Calculate the equilibrium constant for this reaction. b. If 0.20 mole of B and 0.20 mole of C are added to this system, what will happen to A (i.e. will it increase or decrease)? Set up an expression to show how you would determine what will the new equilibrium concentration of would be. You need not solve, but I've solved for you in the solutions.

a) 102.4 b) 0.091M

A 50.0-mL sample of 0.200 M CH3COOH solution is titrated with 0.100 M NaOH. Calculate the pH of the solution after the following volume of the NaOH solution has been added: a. 0mL b. 25mL c. 100 mL d. 125 mL (*Ka=1.8E-5)

a) 2.72 b) 4.30 c) 8.79 d) 12.15

Calculate the ratio of [NH3]/[NH4+] concentrations that gives: a. a solution of pH = 9.55 b. a solution of pH = 9.10 (*pKa=9.25)

a) 2:1 b) 0.708:1

Calculate the pH for each of the following buffer solutions: a. 0.10M HF and 0.20M KF (*pKa of HF=3.149) b. 0.040 M CH3COOH and 0.25 M Ba(CH3COO)2 (*pKa of CH3COOH=4.74) c. 0.10 M NH3 and 0.20 M NH4Br (*pKa of NH4+=9.25)

a) 3.45 b) 5.84 c) 8.95

Calculate the solubility product constants for the following compound given their solubility data: a. SrCrO4, 1.2 mg/mL b. Fe(OH)2, 1.1E10-3 g/L c. SnI2, 10.9 g/L

a) 3.5E-5 b) 7.3E-15 c) 1E-4

Calculate the pH at the equivalence point of the titration of 100.0 mL of each of the following with 0.150 M HNO3: a. 1.000 M NH3 b. 0.100 M NH3 c. 0.0100 M NH3 (*Ka=5.6E-10)

a) 5.07 b) 5.24 c) 5.64

Ethylamine (C2H5NH2) is a weak organic base with a Kb of 6.41x10-4 at 25 oC. Suppose you were to titrate 40.0 mL of a 0.100 M aqueous solution of ethylamine with a 0.100 M HCl solution. a. What is the pH at the equivalence point? a. What is the pH after the addition of 15.00 mL of HCl?

a) 6.05 b) 11.02

Calculate the pH of a 1.25 M solution of each of the following. Assume that Group I ions do not hydrolyze. a. NaCH3COO (*Kb=5.6E-10) b. KNO2 (*Kb=2.2E-11) c. LiCN (*Kb=2E-5)

a) 9.42 b) 8.72 c) 11.70

Predict which acid of each pair is the stronger acid. Justify your answer. a. H2SO4 or H2SeO4 b. HClO2 or HIO2 c. H2O or NH3 d. HCl or HBr e. HClO3 or HClO2

a) H2SO4 (S more electronegative than Se- H2SO4 more acidic; S smaller than Se-H2SO4 more acidic) b) HClO2 (Cl more electronegative than I; HClO2 more acidic; Cl smaller- HClO2 more acidic) c) H2O (Oxidation of O larger than N; H2O more acidic; O smaller than N; H2O less acidic; O more electronegative than N; H2O more acidic *Rule of Thumb: polarity governs in same row.) d) HBr (Cl more electronegative than Br-HCl more acidic; Br larger than Cl... weaker bond- HBr more acidic *Rule of Thumb: bond strength governs in same column) e) HClO3 (more positive oxidation number)

In each of the following pairs, predict which species is the stronger acid (circle your choice): HCO CHO 33 a. H2Se or H3As b. H3PO4 or H3AsO4 c. H2CO3 or HCO3 d. H2SorH2O

a) H2Se (same row; electronegativity governs) b) H3PO4 (oxoacids with same O.N. on central atom; P more electronegative) c) H2CO3 (Ka1>Ka2; harder to pull H+ off anion) d) H2S (same column; size governs)

Predict which base of each pair is the stronger base. Justify your answer. a. NO2- or NO3- b. ClO3- or IO3- c. HSO3- or SO32- d. HSO3- or HSO4- e. F- or Cl-

a) NO2- (HNO3 is a stronger acid that HNO2 because of the oxidation number of N so NO3- is a weaker base than NO2-) b) IO3- (HClO3 is a stronger acid that HIO3 because Cl is more electronegative so ClO3- is a weaker base than IO3-) c) SO32- (H2SO3 is a stronger acid than HSO3- because Ka1>Ka2 so HSO3- is a weaker base than H2SO3) d) HSO3- (H2SO4 is a stronger acid than H2SO3 because of larger oxidation number on S so HSO4- is a weaker base than HSO3-) e) F- (HCl is a stronger acid than HF so Cl- is a weaker base than F-)

Calculate the concentration of hydronium and hydroxide ions, pH and pOH of the following solutions: (a) 0.065 M NaOH; (b) 0.065 M HCl; (c) 0.065 M Ba(OH)2.

a) [H+] = 1.54E-13 [OH-]= 0.065M pH= 12.81 pOH= 1.19 b) [H+] = 0.065M [OH-]= 1.54E-13 pH= 1.19 pOH= 12.81 c) [H+] = 7.69E-14M [OH-]= 0.13M pH= 13.1 pOH= 0.886

The ocean, fortunately, has a natural buffering capacity, thanks in part to dissolved salts. Would you expect aqueous solutions of the following salts to be acidic, basic, or neutral (please note that these are not all aquatically-relevant!)? Assume that only metal cations with a +3 charge or higher hydrolyze. a. CaCO3 b. KCN c. NaCl d. NH4NO3

a) basic b) basic c) neutral d) acidic

For a gas-phase reaction at 298 K, Ea = 103 kJ/mol, and the rate constant is 0.0858 min-1. a. What is the overall order of the reaction? b. Find the rate constant at 323 K.

a) first order b) 2.14 min^-1

Consider the following endothermic reaction at equilibrium: A(g) + 3B(g) ⇄ 2C(g) Suppose we make each of the following changes, and allow the reaction to reestablish equilibrium. Tell whether the amount of A present at the new equilibrium will be (i) greater than, (ii) less than, or (iii) the same as the amount of A before the change was imposed. a. The temperature is increased. b. The volume is increased. c. The pressure is increased. d. More B is added. e. More C is added. f. A small amount of A is removed.

a) less A b) more A c) less A d) less A e) more A f) more A

For each of the following solutions, predict whether the solubility of the solute should be high or low. Justify your answers. (a) LiCl in hexane, C6H14 (b) BaCl2 in H2O (c) C6H14 in H2O (d) CCl4 in C6H14 (e) CH3NH2 in H2O (f) Na2SO4 in octane, C8H18

a) low b) high c) low d) high e) high f) low

Consider the following exothermic reaction at equilibrium: A(g) + 3B(g) ⇄ 2C(g) + 3D(g) Suppose we make each of the following changes, and allow the reaction to reestablish equilibrium. Tell whether the amount of B present at the new equilibrium will be (i) greater than, (ii) less than, or (iii) the same as the amount of B before the change was imposed. a. The temperature is increased while the volume is kept constant. b. More A is added. c. More C is added. d. A small amount of D is removed. e. The volume is decreased.

a) more B b) less B c) more B d) less B e) more B

Write the balanced equation for an acid-base reaction that would produce each of the following salts; predict whether an aqueous solution of each salt is acidic, basic, or neutral. Assume that only metal ions with a +3 charge or higher hydrolyze. a. NaNO3 b. Na2S c. AlCl3 d. Ba(CH3COO)2 e. (NH4)2SO4 (Ka>Kb)

a) neutral b) basic c) acidic d) basic e) acidic

Predict whether the solution of the following salt will be neutral, basic, or acidic. Assume that Group I ions do not hydrolyze. a. NaBr b. KF c. NH4NO3 d. CsNO3 e. FeCl3 f. NaHSO3.

a) neutral b) basic c) acidic d) neutral e) acidic f) acidic

Calculate the pH and pOH of the following solutions: a. 0.065 M NaOH b. 0.065 M HCl c. 0.065 M Ba(OH)2

a) pH=12.81 pOH=1.19 b) pH=1.19 pOH=12.81 c) pH=13.11 pOH=0.886

Calculate the molar solubilities, concentrations of constituent ions, and solubilities in grams per liter for the following compounds at 25°C: a. CuI (Ksp= 5.1E-12; MM= 190.5 g/mol b. PbF2 (Ksp= 4.1E-18; MM= 245.2 g/mol) c. Ca3(PO4)2 (Ksp= 1.2E-26; MM= 310 g/mol)

a) s= 2.26E-6 mol/L 4.3E-4 g/L [Cu+]=2.26E-6 M [I-]=2.26E-6 M b) s= 0.0022 mol/L 0.49 g/L [Pb2+]= 0.0022M [F-]= 0.0044 M c) s= 2.6E-6 mol/L 7.95E-4 g/L [Ca2+]= 8.06E-4 M [PO4 3-]= 5.2E-6 M

The rate constant for the decomposition of NO2 at a certain temperature is 1.70 M-1·min-1. NO2 →NO+1⁄2O2 a. What is the overall order of the reaction? b. Find the time, in seconds, needed to decrease initial 2.00 mol/L of NO2 to 1.25 mol/L. c. What is the half-life of this reaction?

a) second order b) 10.6 sec c) 17.6 sec

The rate constant for the following gas-phase reaction is 0.0442 M-1·s-1. We start with 0.135 mol of C2F4 in a 2.00-liter container, with no C4H8 initially present. C2F4 → 1⁄2C4F8 a. What is the order of the decomposition? b. What will be the concentration of C2F4 after 1.00 hour? c. What will be the concentration of C4F8 after 1.00 hour? d. What is the half-life of the reaction for the initial C2F4 concentration given in part (a)?

a) second order b) [C2F4]=0.0057M c) [C4F8]=0.0309M d) 335 sec

Which of the following solutions are buffers? Explain your decision for each solution. a. 0.10 M HCN and 0.10 M NaCN b. 0.10 M NaCN and 0.10 M NaCl c. 0.10 M NH3 and 0.20 M NH4Br d. 0.10 M NaOH and 0.90 M KOH

a,c

What are the units for the rate constant for a second order reaction if the rate is measured in atm/sec?

atm^-1∙sec^-1

A solution obtained by dissolving 3.48 g of calcium nitrate in 200 g of water has a freezing point of - 0.491°C. Calculate the van't Hoff coefficient of Ca(NO3)2 in this solution. MM of CaNO3 = 164 g Kf = 1.86 C/m

i = 2.5

A certain aqueous HNO2 solution has a pH of 2.19. If solid NaNO2 is added to the solution, will the pH increase, decrease, or remain the same? Assume that there is no volume change upon addition of NaNO2.

increase

The pKa of propanoic acid is 4.89. The pKa of lactic acid is 3.85. Which acid is stronger?

lactic acid

A 0.0730 M solution of a monoprotic acid is 1.07% ionized. What is the pH of this solution? What is the Ka and pKa of the acid?

pH = 3.1 Ka = 8.6E-6 pKa = 5.07

The Ka of the acid-base indicator cresol red is around 5x10-9. For which titration would this indicator serve most useful as an indicator: a weak acid/strong base or strong acid/weak base?

weak acid/strong base