A 100.0-mL sample of spring water was treated to convert any iron present to Fe21. Addition of 25.00 mL of 0.002517 M K2Cr2O7 resulted in the reaction 6Fe21 + Cr2O7 22 + 14H1 → 6Fe31 + 2Cr31 + 7H2O The excess K2Cr2O7 was back-titrated with 8.53 mL of 0.00949 M Fe21 solution. Calculate the concentration of iron in the sample in parts per million.
> Scott Kelly is reviewing MasterToy’s financial statements in order to estimate its sustainable growth rate. Consider the information presented in the following exhibit. a. Identify and calculate the components of the DuPont formula. b.
> Calculate the pH of the solution that results when 20.0 mL of 0.1750 M formic acid is a. Diluted to 45.0 ml with distilled water. b. Mixed with 25.0 ml of 0.140 M NaOH solution. c. Mixed with 25.0 ml of 0.200 M NaOH solution. d. Mixed with 25.0 ml of 0.2
> Calculate the pH of a solution prepared by a. Dissolving 1.87 g of picric acid, (NO2)3C6H2OH(229.11 g>mol), in 100 mL of water. b. diluting 10.0 mL of the solution in (a) to 100 mL c. diluting 10.0 mL of the solution in (b) to 1.00 L
> a. Calculate the pH of a solution prepared by b. Dissolving 36.5 g of lactic acid in water and diluting to 500 mL c. Diluting 25.0 mL of the solution in (a) to 250 mL Diluting 10.0 mL of the solution in (b) to 1.00 L
> Calculate the pH of a solution that is a. b. c.
> Calculate the pH of a solution in which the concentration of piperidine is a. b. c.
> Calculate the pH of a solution that is a. b. c.
> Calculate the pH of an ammonia solution that is a. b. c.
> Calculate the pH of a solution that is a. b. c.
> Calculate the pH of an aqueous solution that is a. b. c.
> What is the mass in grams of a. 2.25 mol of KBr? b. 15.5 mmol of PbO? c. 5.04 mol of CaSO4? d. 10.9 mmol of Fe (NH4)2(SO4)2.6H2O?
> The hydrogen sulfide in a 40.0-g sample of crude petroleum was removed by distillation and collected in a solution of CdCl2. The precipitated CdS was then filtered, washed, and ignited to CdSO4. Calculate the percentage of H2S in the sample if 0.079 g of
> Determination of phosphorous in blood serum gave results of 4.40, 4.42, 4.60, 4.48, and 4.50 ppm P. Determine whether the 4.60 ppm result is an outlier or should be retained at the 95% confidence level.
> Calculate the hydroxide ion concentration and the pH of a 0.0150 M Ba1OH22 solution a. Neglecting activities. b. Using activities (see Chapter8).
> Calculate the hydronium ion concentration and pH of a solution that is 0.0500 M in HCl a. Neglecting activities. b. Using activities (see Chapter 8).
> Calculate the pH of the solution that results when mixing 15.0 mL of 0.2500 M HCl with 25.0 mL of a. Distilled water. b. 0.132 M AgNO3. c. 0.132 M NaOH. d. 0.132 M NH3. e. 0.232 M NaOH.
> What is the pH of the solution that results when 0.093 g of Mg(OH)2 is mixed with a. 75.0 mL of 0.0500 M HCl? b. 100.0 mL of 0.0500 M HCl? c. 15.0 mL of 0.0500 M HCl? d. 30.0 mL of 0.0500 M MgCl2?
> What is the pH of a 215 108 MHCl solution (see hint in Problem 12-15)?
> What is the pH of a solution that is 2.00 8 M in NaOH? (Hint: In such a dilute solution, you must take into account the contribution of H2O to the hydroxide ion concentration.)
> Calculate the pH of a solution that contains 2.50% (w/w) NaOH and has a density of 1.015 g/mL.
> What is the pH of an aqueous solution that is 3.00% HCl by mass and has a density of 1.015 g/mL?
> Using the data in Problem 12-10, calculate the pH of a 150 1022MNaOH solution at a. 0°C. b. 50°C. c. 100°C.
> A 0.7812-g sample of impure Al2(CO3)3 decomposed with HCl; the liberated CO2 was collected on calcium oxide and found to weigh 0.04380 g. Calculate the percentage of aluminum in the sample.
> Using the data in Problem 12-10, calculate pKw at a. 0°C. b. 50°C. c. 100°C.
> Apply the Q test to the following data sets to determine whether the outlying result should be retained or rejected at the 95% confidence level. a. 95.10, 94.62, 94.70 b. 95.10, 94.62, 94.65, 94.70
> What hydroxide concentration is required to a. Initiate precipitation of Al3+ from a 3.89 × 10-2M solution of Al2(SO4)3? b. Lower the Al3+ concentration in the foregoing solution to 4.75 × 10-7 M?
> Values for Kw at 0, 50, and 100C are 1.14 1015, 5.471014, and 4.9 1013, respectively. Calculate the pH for a neutral solution at each of these temperatures.
> The procedure described in Problem 12-8 was used to determine pH with methyl orange as the indicator. The concentration ratio of the acid to base form of the indicator was 1.84. Calculate the pH of the solution.
> Before glass electrodes and pH meters became widely used, pH was often determined by measuring the concentration of the acid and base forms of the indicator colorimetrically (see Chapter 24 for details). If bromothymol blue is introduced into a solution
> Which solute wouldprovide the sharperend pointinatitration with 0.10MNaOH: a. 0.10 M nitrous acid or 0.10 M iodic acid? b. 0.10 M salicylic acid or 0.10 M acetic acid? c. 0.10 M hypochlorous acid or 0.10 M pyruvic acid? d. 0.10 M anilinium hydrochloride
> Which solute would provide the sharper end point in a titration with 0.10 M HCl: a. 0.10 M NaOCl or 0.10 M hydroxylamine? b. 0.10 M hydrazine or 0.10 M NaCN? c. 0.10 M methylamine or 0.10 M hydroxylamine? d. 0.10 M NH3 or 0.10 M sodium phenolate?
> What variables can cause the pH range of an indicator to shift?
> Distinguish between a. The equivalence point and the end point of a titration. b. A primary standard and a secondary standard.
> Precipitates used in the gravimetric determination of uranium include Na2U2O7 (634.0 g/mol), (UO2)2P2O7 (714.0 g/mol), and V2O5 . 2UO3 (753.9 g/mol). Which of these weighing forms provides the greatest mass of precipitate from a given quantity of uraniu
> Write two equations that—along with the stoichiometric factor—form the basis for the calculations of volumetric titrations.
> Define a. Millimole. b. Titration. c. Stoichiometric ratio. d. Titration error.
> Apply the Q test to the following data sets to determine whether the outlying result should be retained or rejected at the 95% confidence level. a. 51.27, 51.61, 51.84, 51.70 b. 7.295, 7.284, 7.388, 7.292
> A solution was prepared by dissolving 367 mg of K3Fe1CN26 1329.2 g>mol2 in sufficient water to give 750.0 mL. Calculate a. The molar analytical concentration of K3Fe1CN26. b. The molar concentration of K1. c. The molar concentration of Fe1CN26 32. d.
> What is the mass in milligrams of a. 0.367 mol of HNO3? b. 245 mmol of MgO? c. 12.5 mol of NH4NO3? d. 4.95 mol of 1NH422Ce1NO326 (548.23 g/mol)?
> A solution was prepared by dissolving 7.48 g of KCl # MgCl2 # 6H2O 1277.85 g>mol2 in sufficient water to give 2.000 L. Calculate a. The molar analytical concentration of kcl.Mgcl2 in this solution. b. The molar concentration of Mg21. c. The molar conc
> a. A 0.1527-g sample of primary-standard AgNO3 was dissolved in 502.3 g of distilled water. Calculate the weight molar concentration of Ag1 in this solution. b. The standard solution described in part (a) was used to titrate a 25.171-g sample of a KSCN
> a. A 0.3147-g sample of primary-standard-grade Na2C2O4 was dissolved in H2SO4 and titrated with 31.67 mL of dilute KMnO4: 2MnO4 2 1 5C2O4 22 1 16H1 S 2Mn21 1 10CO21g2 1 8H2O Calculate the molar concentration of the KMnO4 solution. b. The iron in a 0.
> A 0.1475-M solution of Ba1OH22 was used to titrate the acetic acid (60.05 g/mol) in a dilute aqueous solution. The following results were obtained. a. Calculate the mean w/v percentage of acetic acid in the sample. b. Calculate the standard deviation
> The ethyl acetate concentration in an alcoholic solution was determined by diluting a 10.00-mL sample to 100.00 mL. A 20.00-mL portion of the diluted solution was refluxed with 40.00 mL of 0.04672 M KOH: CH3COOC2H5 + OH2 → CH3COO2 + C2H5OH After cooling,
> What mass of AgI can be produced from a 0.512-g sample that assays 20.1% AlI3?
> A solution of Ba1OH22 was standardized against 0.1215 g of primary-standard-grade benzoic acid, C6H5COOH 1122.12 g>mol2. An end point was observed after addition of 43.25 mL of base. a. Calculate the molar concentration of the base. b. Calculate the st
> The thiourea in a 1.455-g sample of organic material was extracted into a dilute H2SO4 solution and titrated with 37.31 mL of 0.009372 M Hg21 via the reaction 41NH222CS + Hg21 → 31NH222CS44Hg21 Find the percentage of 1NH222CS 176.12 g>mol2 in the sample.
> The arsenic in a 1.203-g sample of a pesticide was converted to H3AsO4 by suitable treatment. The acid was then neutralized, and 40.00 mL of 0.05871 M AgNO3 was added to precipitate the arsenic quantitatively as Ag3AsO4. The excess Ag1 in the filtrate an
> Three different analytical methods are compared for determining Ca in a biological sample. The laboratory is interested in knowing whether the methods differ. The results shown next represent Ca results in ppm determined by an ion-selective electrode (IS
> A 4.912-g sample of a petroleum product was burned in a tube furnace, and the SO2 produced was collected in 3% H2O2. Reaction: SO21g2 + H2O2 → H2SO4 A 25.00-mL portion of 0.00873 M NaOH was introduced into the solution of H2SO4, following which the exces
> What CrO42- concentration is required to a. Initiate precipitation of Ag2CrO4 from a solution that is 5.24 × 10-3 M in Ag+? b. Lower the concentration of Ag+ in a solution to 7.82 × 10-7 M?
> Titration of the I2 produced from 0.1142 g of primary-standard KIO3 required 27.95 mL of sodium thiosulfate. IO3 2 + 5I2 + 6H1 → 3I2 + 3H2O I2 + 2S2O3 22 → 2I2 + S4O6 22 Calculate the concentration of the Na2S2O3.
> Titration of 50.00 mL of 0.04715 M Na2C2O4 required 39.25 mL of a potassium permanganate solution. 2MnO4 2 + 5H2C2O4 + 6H1 → 2Mn21 + 10CO21g2 + 8H2O Calculate the molar concentration of the KMnO4 solution.
> The week 3 measurement in the data set of Problem 5-16 is suspected of being an outlier. Use the Q test to determine if the value can be rejected at the 95% confidence level. Answer
> Treatment of a 0.3500-g sample of impure potassium chloride with an excess of AgNO3 resulted in the formation of 0.3846 g of AgCl. Calculate the percentage of KCl in the sample.
> Write an equation showing how the mass of the substance sought can be converted to the mass of the weighed substance on the right.
> Suggest a precipitation method for separation of K+ from Na+ and Li+.
> What is peptization, and how is it avoided?
> Suggest a method by which Pb21 can be precipitated homogeneously as PbS.
> A 0.4126-g sample of primary-standard Na2CO3 was treated with 40.00 mL of dilute perchloric acid. The solution was boiled to remove CO2, following which the excess HClO4 was back-titrated with 9.20 mL of dilute NaOH. In a separate experiment, it was esta
> Calculate the solubility of the solutes in Problem 7-10 for solutions in which the cation concentration is 0.030 M.
> Why do molar concentrations of some species appear as multiples in charge-balance equations?
> In the margin note on page 215, we suggest that the term mass-balance equation may be something of a misnomer. Using a specific chemical system, discuss mass balance and show that mass balance and concentration balance are equivalent.
> Find the amount in millimoles of the indicated species in a. 12.92 g of NaHCO3 b. 57 mg of MgNH4PO4. c. 850 mg of P2O5. d. 40.0 g of CO2.
> Define a. Molar mass. b. Millimole. c. Millimolar mass. d. Parts per billion.
> Why are simplifying assumptions in equilibrium problems restricted to relationships that are sums or differences?
> The phosphorous content in ppm was measured for three different soil locations. Five replicate determinations were made on each soil sample. A partial ANOVA table follows: a. Fill in the missing entries in the ANOVA table. b. State the null and alternati
> Demonstrate how the sulfide ion concentration is related to the hydronium ion concentration of a solution that is kept saturated with hydrogen sulfide.
> Calculate the molar solubility of Tl2S as a function of pH over the range of pH 10 to pH 1. Find values at every 0.5 pH unit, and use the charting function of Excel to plot solubility versus pH.
> In contrast to many salts, calcium sulfate is only partially dissociated in aqueous so Kd = 5.2 × 10-3 The solubility-product constant for CaSO4 is 2.6 × 10-5 . Calculate the solubility of CaSO4 in (a) water and(b) 0.0100 M Na
> The equilibrium constant for formation of CuCl2 2 is given by What is the solubility of CuCl in solutions having the following analytical NaClconcentrations: a. 5.0 M? b. 5.0 × 10-1 M? c. 5.0 × 10-2 M? d. 5.0 × 1
> A 0.5002-g sample that assayed 96.4% Na2SO4 required 48.63 mL of a barium chloride solution. Reaction: Ba21 + SO4 22 → BaSO4(s) Calculate the analytical molar concentration of BaCl2 in the solution.
> What mass of AgBr dissolves in 200 mL of 0.200 M NaCN?
> Using 1.0 × 10-6 M as the criterion for quantitative removal, determine whether it is feasible to use a. SO4 22 to separate Ba21 and Sr21 in a solution that is initially 0.030 M in Sr21 and 0.15 M in Ba21. b. SO4 22 to separate Ba21 and Ag1 in a soluti
> Silver ion is being considered for separating I- from SCN- in a solution that is 0.040 M in KI and 0.080 M in NaSCN. a. What Ag1 concentration is needed to lowerthe I- concentration to 1.0 × 10-6 M? b. What is the Ag1 concentration of the solution when
> A solution is 0.030 M in Na2SO4 and 0.040 M in NaIO3.To this is added a solution containing Ba21. Assuming that no HSO4 - is present in the original solution, a. which barium salt will precipitate first? b. what is the Ba21 concentration as the first p
> Dilute NaOH is introduced into a solution that is 0.050 M in Cu21 and 0.040 M in Mn21. a. Which hydroxide precipitates first? b. What OH2 concentration is needed to initiate precipitation of the first hydroxide? c. What is the concentration of the cat
> Calculate the solubility-product constant for each of the following substances, given that the molar concentrations of their saturated solutions are as indicated:
> Sir William Ramsey (Lord Rayleigh) prepared nitrogen samples by several different methods. The density of each sample was measured as the mass of gas required to fill a particular flask at a certain temperature and pressure. Masses of nitrogen samples pr
> Calculate the molar solubility of ZnCO3 in a solution buffered to a pH of 7.50.
> Calculate the molar solubility of ZnCO3 in a solution buffered to a pH of 7.00.
> Calculate the molar solubility of MnS (pink) in a solution with a constant 3H3O14 of a. 3.00 × 10-5 M b. 2.50 × 10-7 M
> A 0.4723-g sample of primary-standard-grade Na2CO3 required 34.78 mL of an H2SO4 solution to reach the end point in the reaction CO3 22 + 2H1 → H2O + CO21g2 What is the molar concentration of the H2SO4?
> Calculate the concentration of CuS in a solution in which 3H3O14 is held constant at a. 2.0 × 10-1 M b. 2.0 × 10-4 M.
> Calculate the molar solubility of PbS in a solution in which 3H3O14 is held constant at a. 3.0 × 10-1 M b. 3.0 × 10-4 M.
> Calculate the molar solubility of BaSO4 in a solution in which 3H3O14 is a. 3.5 M. b. 0.75 M. c. 0.080 M. d. 0.100 M.
> Calculate the molar solubility of ZnC2O4 in a solution that has a fixed H3O1 concentration of a. 1.0 × 10-6 M. b. 1.0 × 10-7 M. c. 1.0 × 10-9 M. d. 1.0 × 10-11 M.
> Write the charge-balance equations for the solutions in Problem 9-5.
> Write the mass-balance expressions for a solution that is a. 0.2 M in HF. b. 0.25 M in NH3. c. 0.10 M in H3PO4. d. 0.15 M in Na2HPO4. e. 0.0500 M in HClO2 and 0.100 M in NaClO2. f. 0.12 M in NaF and saturated with CaF2. g. 0.100 M in NaOH and satu
> Neglecting any effects caused by volume changes, would you expect the ionic strength to (1) increase, (2) decrease, or (3) remain essentially unchanged when NaOH is added to a dilute solution of a. magnesium chloride [Mg1OH221s2] forms? b. hydrochlor
> Two different analytical methods were used to determine residual chlorine in sewage effluents. Both methods were used on the same samples, but each sample came from various locations with differing amounts of contact time with the effluent. Two methods w
> Find the amount of the indicated element (in moles) in a. 5.32 g of B2O3. b. 195.7 mg of Na2B4O7 ? 10H2O. c. 4.96 g of Mn3O4. d. 333 mg of CaC2O4.
> List several general properties of activity coefficients.
> Describe the preparation of a. 1.00 L of 0.150 M KMnO4 from the solid reagent. b. 2.50 L of 0.500 M HClO4, starting with a 9.00 M solution of the reagent. c. 400 mL of a solution that is 0.0500 M in I2, starting with MgI2. d. 200 mL of 1.00% (w>v) aq
> Make a distinction between a. activity and activity coefficient. b. thermodynamic and concentration equilibrium constants.
> Design and construct a spreadsheet to calculate activity coefficients in a format similar to Table 8-2. Enter values of aX in cells A3, A4, A5, and so forth, and enter ionic charges in cells B3, B4, B5, and so forth. Enter in cells C2:G2 the same set of
> Calculate the % relative error in hydronium ion concentration by using concentrations instead of activities in calculating the pH of the following buffer solutions using the thermodynamic constants found in Appendix 3. a. 0.175 M HOAc and 0.275 M NaOAc
> Calculate the % relative error in solubility by using concentrations instead of activities for the following compounds in 0.0350 M KNO3 using the thermodynamic solubility products listed in Appendix 2. a. CuCl 1aCu1 5 0.3 nm2 b. Fe1OH22 c. Fe1OH23 d. La
> Calculate the solubilities of the following compounds in a 0.0167 M solution of Ba1NO322 using (1) activities and (2) molar concentrations: a. AgIO3. b. Mg1OH22. c. BaSO4. d. La1IO323.
> Calculate the solubilities of the following compounds in a 0.0275 M solution of Mg1ClO422 using (1) activities and (2) molar concentrations: a. AgSCN. b. PbI2. c. BaSO4. d. Cd2Fe1CN26.
