Compounds of Sc3 are not colored, but those of Ti3 and V3

You isolate a compound with the formula PtCl4  2KCl. From electrical conductance tests of an aqueous solution of the compound, you find that three ions per formula unit are present, and you also notice that addition of AgNO3 does not cause a precipitate. Give the formula for this compound that shows the complex ion present. Explain your findings. Name this compound

Both Ni(NH3)4 2 and Ni(SCN)4 2 have four ligands. The first is paramagnetic, and the second is diamagnetic. Are the complex ions tetrahedral or square planar? Explain.

Which is more likely to be paramagnetic, Fe(CN)6 4 or Fe(H2O)6 2? Explain.

A metal ion in a high-spin octahedral complex has two more unpaired electrons than the same ion does in a low-spin octahedral complex. Name some possible metal ions for which this would be true.

Oxalic acid is often used to remove rust stains. What properties of oxalic acid allow it to do this?

Four different octahedral chromium coordination compounds exist that all have the same oxidation state for chromium and have H2O and Cl as the ligands and counterions. When 1 mol of each of the four compounds is dissolved in water, how many mol of silver chloride will precipitate upon addition of excess AgNO3?

Figure 21.17 shows that the cis isomer of Co(en)2Cl2 is optically active while the trans isomer is not optically active. Is the same true for Co(NH3)4Cl2 ? Explain.

A certain first-row transition metal ion forms many different colored solutions. When four coordination compounds of this metal,each having the same coordination number, are dissolved in water, the colors of the solutions are red, yellow, green, and blue. Further experiments reveal that two of the complex ions are paramagnetic with four unpaired electrons and the other two are diamagnetic. What can be deduced from this information about the four coordination compounds?

CoCl4 2 forms a tetrahedral complex ion and Co(CN)6 3 forms an octahedral complex ion. What is wrong about the following statements concerning each complex ion and the d orbital splitting diagrams? a. CoCl4 2 is an example of a strong-field case having two unpaired electrons. b. Because CN is a weak-field ligand, Co(CN)6 3 will be a lowspin case having four unpaired electrons

The following statements discuss some coordination compounds. For each coordination compound, give the complex ion and the counterions, the electron configuration of the transition metal, and the geometry of the complex ion. a. CoCl2 6H2O is a compound used in novelty devices that predict rain. b. During the developing process of black-and-white film, silver bromide is removed from photographic film by the fixer. The major component of the fixer is sodium thiosulfate. The equation for the reaction is: c. In the production of printed circuit boards for the electronics industry, a thin layer of copper is laminated onto an insulating plastic board. Next, a circuit pattern made of a chemically resistant polymer is printed on the board. The unwanted copper is removed by chemical etching, and the protective polymer is finally removed by solvents. One etching reaction is: Assume these copper complex ions have tetrahedral geometry.

When concentrated hydrochloric acid is added to a red solution containing the Co(H2O)6 2 complex ion, the solution turns blue as the tetrahedral CoCl4 2 complex ion forms. Explain this color change.

Tetrahedral complexes of Co2 are quite common. Use a d-orbital splitting diagram to rationalize the stability of Co2 tetrahedral complex ions.

Which of the following ligands are capable of linkage isomerism? Explain your answer

Compounds of copper(II) are generally colored, but compounds of copper(I) are not. Explain. Would you expect Cd(NH3)4Cl2 to be colored? Explain

Compounds of Sc3 are not colored, but those of Ti3 and V3 are. Why? 1

Almost all metals in nature are found as ionic compounds in ores instead of being in the pure state. Why? What must be done to a sample of ore to obtain a metal substance that has desirable properties?

Write electron configurations for the following metals. a. Ni b. Cd c. Zr d. Os

Write electron configurations for the following ions. a. Ni2 c. Zr3 and Zr4 b. Cd2 d. Os2 and Os3 19.

Write electron configurations for each of the following. a. Ti, Ti2, Ti4 b. Re, Re2, Re3 c. Ir, Ir2, Ir3 20.

Write electron configurations for each of the following. a. Cr, Cr2, Cr3 b. Cu, Cu, Cu2 c. V, V2, V3 21.

What is the electron configuration for the transition metal ion in each of the following compounds? a. K3[Fe(CN)6] b. [Ag(NH3)2]Cl c. [Ni(H2O)6]Br2 d. [Cr(H2O)4(NO2)2]I

What is the electron configuration for the transition metal ion(s) in each of the following compounds? a. (NH4)2[Fe(H2O)2Cl4] b. [Co(NH3)2(NH2CH2CH2NH2)2]I2 c. Na2[TaF7] d. [Pt(NH3)4I2][PtI4] Pt forms 2 and 4 oxidation states in compounds.

Molybdenum is obtained as a by-product of copper mining or is mined directly (primary deposits are in the Rocky Mountains in Colorado). In both cases it is obtained as MoS2, which is then converted to MoO3. The MoO3 can be used directly in the production of stainless steel for high-speed tools (which accounts for about 85% of the molybdenum used). Molybdenum can be purified by dissolving MoO3 in aqueous ammonia and crystallizing ammonium molybdate. Depending on conditions, either (NH4)2Mo2O7 or (NH4)6Mo7O24 4H2O is obtained. a. Give names for MoS2 and MoO3. b. What is the oxidation state of Mo in each of the compounds mentioned above?

Titanium dioxide, the most widely used white pigment, occurs naturally but is often colored by the presence of impurities. The chloride process is often used in purifying rutile, a mineral form of titanium dioxide. a. Show that the unit cell for rutile, shown below, conforms to the formula TiO2. (Hint: Recall the discussion in Sections 10.4 and 10.7.) O Ti b. The reactions for the chloride process are Assign oxidation states to the elements in both reactions. Which elements are being reduced, and which are being oxidized? Identify the oxidizing agent and the reducing agent in each reaction

What is the lanthanide contraction? How does the lanthanide contraction affect the properties of the 4d and 5d transition metals?

We expect the atomic radius to increase down a group in the periodic table. Can you suggest why the atomic radius of hafnium breaks this rule? (See the following data.)

Novelty devices for predicting rain contain cobalt(II) chloride and are based on the following equilibrium: Purple Pink What color will such an indicator be if rain is imminent?

Chromium(VI) forms two different oxyanions, the orange dichromate ion, Cr2O7 2, and the yellow chromate ion, CrO4 2. The equilibrium reaction between the two ions is The following pictures show what happens when sodium hydroxide is added to a dichromate solution. Explain what happened.

A series of chemicals was added to some AgNO3(aq). NaCl(aq) was added first to the silver nitrate solution with the end result shown in test tube 1, NH3(aq) was then added with the end result shown in test tube 2, and HNO3(aq) was added last with the end result shown in test tube 3. Explain the results shown in each test tube. Include a balanced equation for the reaction(s) taking place.

When an aqueous solution of KCN is added to a solution containing Ni2 ions, a precipitate forms, which redissolves on addition of more KCN solution. Write reactions describing what happens in this solution. [Hint: CN is a BrnstedLowry base and a Lewis base.]

Consider aqueous solutions of the following coordination compounds: Co(NH3)6I3, Pt(NH3)4I4, Na2PtI6, and Cr(NH3)4I3. If aqueous AgNO3 is added to separate beakers containing solutions of each coordination compound, how many moles of AgI will precipitate per mole of transition metal present? Assume that each transition metal ion forms an octahedral complex.

A coordination compound of cobalt(III) contains four ammonia molecules, one sulfate ion, and one chloride ion. Addition of aqueous BaCl2 solution to an aqueous solution of the compound gives no precipitate. Addition of aqueous AgNO3 to an aqueous solution of the compound produces a white precipitate. Propose a structure for this coordination compound.

Name the following complex ions. a. Ru(NH3)5Cl2 c. Mn(NH2CH2CH2NH2)3 2 b. Fe(CN)6 4 d. Co(NH3)5NO2 2 3

Name the following complex ions. a. Ni(CN)4 2 c. Fe(C2O4)3 3 b. Cr(NH3)4Cl2 d. Co(SCN)2(H2O)4 3

Name the following coordination compounds. a. [Co(NH3)6]Cl2 d. K4[PtCl6] b. [Co(H2O)6]I3 e. [Co(NH3)5Cl]Cl2 c. K2[PtCl4] f. [Co(NH3)3(NO2)3

Name the following coordination compounds. a. [Cr(H2O)5Br]Br2 c. [Fe(NH2CH2CH2NH2)2(NO2)2]Cl b. Na3[Co(CN)6] d. [Pt(NH3)4I2][PtI4]

Give formulas for the following. a. potassium tetrachlorocobaltate(II) b. aquatricarbonylplatinum(II) bromide c. sodium dicyanobis(oxalato)ferrate(III) d. triamminechloroethylenediaminechromium(III) iodide

Give formulas for the following complex ions. a. tetrachloroferrate(III) ion b. pentaammineaquaruthenium(III) ion c. tetracarbonyldihydroxochromium(III) ion d. amminetrichloroplatinate(II) ion

Draw geometrical isomers of each of the following complex ions. a. [Co(C2O4)2(H2O)2]  c. [Ir(NH3)3Cl3] b. [Pt(NH3)4I2] 2 d. [Cr(en)(NH3)2I2]

Draw structures of each of the following. a. cis-dichloroethylenediamineplatinum(II) b. trans-dichlorobis(ethylenediamine)cobalt(II) c. cis-tetraamminechloronitrocobalt(III) ion d. trans-tetraamminechloronitritocobalt(III) ion e. trans-diaquabis(ethylenediamine)copper(II) ion

The carbonate ion (CO3 2) can act as either a monodentate or a bidentate ligand. Draw a picture of CO3 2 coordinating to a metal ion as a monodentate and as a bidentate ligand. The carbonate ion can also act as a bridge between two metal ions. Draw a picture of a CO3 2 ion bridging between two metal ions.

BAL is a chelating agent used in treating heavy metal poisoning. It acts as a bidentate ligand. What type of linkage isomers are possible when BAL coordinates to a metal ion?

Draw all geometrical and linkage isomers of Co(NH3)4(NO2)2

Draw all geometrical and linkage isomers of square planar [Pt(NH3)2(SCN)2]

Acetylacetone, abbreviated acacH, is a bidentate ligand. It loses a proton and coordinates as acac, as shown below, where M is a transition metal: Which of the following complexes are optically active: cisCr(acac)2(H2O)2, trans-Cr(acac)2(H2O)2, and Cr(acac)3?

Draw all geometrical isomers of Pt(CN)2Br2(H2O)2. Which of these isomers has an optical isomer? Draw the various optical isomers.

Draw the d-orbital splitting diagrams for the octahedral complex ions of each of the following. a. Fe2 (high and low spin) b. Fe3 (high spin) c. Ni2

Draw the d-orbital splitting diagrams for the octahedral complex ions of each of the following. a. Zn2 b. Co2 (high and low spin) c. Ti3 4

The CrF6 4 ion is known to have four unpaired electrons. Does the F ligand produce a strong or weak field?

The Co(NH3)6 3 ion is diamagnetic, but Fe(H2O)6 2 is paramagnetic. Explain.

How many unpaired electrons are in the following complex ions? a. Ru(NH3)6 2 (low-spin case) b. Ni(H2O)6 2 c. V(en)3 3 52

The complex ion Fe(CN)6 3 is paramagnetic with one unpaired electron. The complex ion Fe(SCN)6 3 has five unpaired electrons. Where does SCN lie in the spectrochemical series relative to CN?

Rank the following complex ions in order of increasing wavelength of light absorbed.

The complex ion [Cu(H2O)6] 2 has an absorption maximum at around 800 nm. When four ammonias replace water, [Cu(NH3)4(H2O)2] 2, the absorption maximum shifts to around 600 nm. What do these results signify in terms of the relative field splittings of NH3 and H2O? Explain.

The following test tubes each contain a different chromium complex ion. For each complex ion, predict the predominant color of light absorbed. If the complex ions are Cr(NH3)6 3, Cr(H2O)6 3, and Cr(H2O)4Cl2 , what is the identity of the complex ion in each test tube? (Hint: Reference the spectrochemical series.) 5

Consider the complex ions Co(NH3)6 3, Co(CN)6 3, and CoF6 3. The wavelengths of absorbed electromagnetic radiation for these compounds (in no specific order) are 770 nm, 440 nm, and 290 nm. Match the complex ion to the wavelength of absorbed electromagnetic radiation.

The wavelength of absorbed electromagnetic radiation for CoBr4 2 is 3.4  106 m. Will the complex ion CoBr6 4 absorb electromagnetic radiation having a wavelength longer or shorter than 3.4  106 m? Explain

The complex ion NiCl4 2 has two unpaired electrons, whereas Ni(CN)4 2 is diamagnetic. Propose structures for these two complex ions.

How many unpaired electrons are present in the tetrahedral ion FeCl4 ?

The complex ion PdCl4 2 is diamagnetic. Propose a structure for PdCl4 2.

A blast furnace is used to reduce iron oxides to elemental iron. The reducing agent for this reduction process is carbon monoxide. a. Given the following data: determine H for the reaction b. The CO2 produced in a blast furnace during the reduction process actually can oxidize iron into FeO. To eliminate this reaction, excess coke is added to convert CO2 into CO by the reaction Using data from Appendix 4, determine H and S for this reaction. Assuming H and S do not depend on temperature, at what temperature is the conversion reaction of CO2 into CO spontaneous at standard conditions? 62.

Use the data in Appendix 4 for the following. a. Calculate H and S for the reaction that occurs in a blast furnace. b. Assume that H and S are independent of temperature. Calculate G at 800.C for this reaction. 63.

Iron is present in the earths crust in many types of minerals. The iron oxide minerals are hematite (Fe2O3) and magnetite (Fe3O4). What is the oxidation state of iron in each mineral? The iron ions in magnetite are a mixture of Fe2 and Fe3 ions. What is the ratio of Fe3 to Fe2 ions in magnetite? The formula for magnetite is often written as FeO Fe2O3. Does this make sense? Explain. 64.

What roles do kinetics and thermodynamics play in the effect that the following reaction has on the properties of steel?

Silver is sometimes found in nature as large nuggets; more often it is found mixed with other metals and their ores. Cyanide ion is often used to extract the silver by the following reaction that occurs in basic solution: Balance this equation by using the half-reaction method

One of the classic methods for the determination of the manganese content in steel involves converting all the manganese to the deeply colored permanganate ion and then measuring the absorption of light. The steel is first dissolved in nitric acid, producing the manganese(II) ion and nitrogen dioxide gas. This solution is then reacted with an acidic solution containing periodate ion; the products are the permanganate and iodate ions. Write balanced chemical equations for both of these steps.

The compound cisplatin, Pt(NH3)2Cl2, has been studied extensively as an antitumor agent. The reaction for the synthesis of cisplatin is: Write the electron configuration for platinum ion in cisplatin. Most d8 transition metal ions exhibit square planar geometry. With this and the name in mind, draw the structure of cisplatin.

Amino acids can act as ligands toward transition metal ions. The simplest amino acid is glycine (NH2CH2CO2H). Draw a structure of the glycinate anion (NH2CH2CO2 ) acting as a bidentate ligand. Draw the structural isomers of the square planar complex Cu(NH2CH2CO2)2.

How many bonds could each of the following chelating ligands form with a metal ion? a. acetylacetone (acacH), a common ligand in organometallic catalysts: b. diethylenetriamine, used in a variety of industrial processes: c. salen, a common ligand for chiral organometallic catalysts: d. porphine, often used in supermolecular chemistry as well as catalysis; biologically, porphine is the basis for many different types of porphyrin-containing proteins, including heme proteins:

The complex ion Ru(phen)3 2 has been used as a probe for the structure of DNA. (Phen is a bidentate ligand.) a. What type of isomerism is found in Ru(phen)3 2? b. Ru(phen)3 2 is diamagnetic (as are all complex ions of Ru2). Draw the crystal field diagram for the d orbitals in this complex ion. Phen  1,10-phenanthroline  N N NH

Hemoglobin (abbreviated Hb) is a protein that is responsible for the transport of oxygen in the blood of mammals. Each hemoglobin molecule contains four iron atoms that serve as the binding sites for O2 molecules. The oxygen binding is pH dependent. The relevant equilibrium reaction is Use Le Chteliers principle to answer the following. a. What form of hemoglobin, HbH4 4 or Hb(O2)4, is favored in the lungs? What form is favored in the cells? b. When a person hyperventilates, the concentration of CO2 in the blood decreases. How does this affect the oxygenbinding equilibrium? How does breathing into a paper bag help to counteract this effect? (Hint: CO2 reacts with water to produce carbonic acid.) c. When a person has suffered a cardiac arrest, an injection of a sodium bicarbonate solution is given. Why is this step necessary? (Hint: CO2 blood levels increase during cardiac arrest.)

Why are CN and CO toxic to humans?

What causes high-altitude sickness, and what is high-altitude acclimatization?

Ethylenediaminetetraacetate (EDTA4) is used as a complexing agent in chemical analysis with the structure shown in Figure 21.7. Solutions of EDTA4 are used to treat heavy metal poisoning by removing the heavy metal in the form of a soluble complex ion. The complex ion essentially eliminates the heavy metal ions from reacting with biochemical systems. The reaction of EDTA4 with Pb2 is Consider a solution with 0.010 mol Pb(NO3)2 added to 1.0 L of an aqueous solution buffered at pH  13.00 and containing 0.050 M Na4EDTA. Does Pb(OH)2 precipitate from this solution? (Ksp for Pb(OH)2  1.2  1015.)

Acetylacetone (see Exercise 69, part a), abbreviated acacH, is a bidentate ligand. It loses a proton and coordinates as acac, as shown below: Acetylacetone reacts with an ethanol solution containing a salt of europium to give a compound that is 40.1% C and 4.71% H by mass. Combustion of 0.286 g of the compound gives 0.112 g Eu2O3. Assuming the compound contains only C, H, O, and Eu, determine the formula of the compound formed from the reaction of acetylacetone and the europium salt. (Assume that the compound contains one europium ion.)

A transition metal compound contains a cobalt ion, chloride ions, and water molecules. The H2O molecules are the ligands in the complex ion and the Cl ions are the counterions. A 0.256-g sample of the compound was dissolved in water, and excess silver nitrate was added. The silver chloride was filtered, dried, and weighed, and it had a mass of 0.308 g. A second sample of 0.416 g of the compound was dissolved in water, and an excess of sodium hydroxide was added. The hydroxide salt was filtered and heated in a flame, forming cobalt(III) oxide. The mass of cobalt(III) oxide formed was 0.145 g. What is the oxidation state of cobalt in the complex ion and what is the formula of the compound?

When aqueous KI is added gradually to mercury(II) nitrate, an orange precipitate forms. Continued addition of KI causes the precipitate to dissolve. Write balanced equations to explain these observations. (Hint: Hg2 reacts with I to form HgI4 2.) Would you expect HgI4 2 to form colored solutions? Explain.

In the production of printed circuit boards for the electronics industry, a 0.60-mm layer of copper is laminated onto an insulating plastic board. Next, a circuit pattern made of a chemically resistant polymer is printed on the board. The unwanted copper is removed by chemical etching, and the protective polymer is finally removed by solvents. One etching reaction is a. Is this reaction an oxidationreduction process? Explain. b. A plant needs to manufacture 10,000 printed circuit boards, each 8.0  16.0 cm in area. An average of 80.% of the copper is removed from each board (density of copper  8.96 g/cm3 ). What masses of [Cu(NH3)4]Cl2 and NH3 are needed to do this? Assume 100% yield.

Use standard reduction potentials to calculate , G, and K (at 298 K) for the reaction that is used in production of gold: The relevant half-reactions are

Until the discoveries of Alfred Werner, it was thought that carbon had to be present in a compound for it to be optically active. Werner prepared the following compound containing OH ions as bridging groups and separated the optical isomers. a. Draw structures of the two optically active isomers of this compound. b. What are the oxidation states of the cobalt ions? c. How many unpaired electrons are present if the complex is the low-spin case?

Draw all the geometrical isomers of [Cr(en)(NH3)2BrCl]. Which of these isomers also have an optical isomer? Draw the various isomers.

A compound related to acetylacetone is 1,1,1-trifluoroacetylacetone (abbreviated Htfa): Htfa forms complexes in a manner similar to acetylacetone. (See Exercise 45.) Both Be2 and Cu2 form complexes with tfa having the formula M(tfa)2. Two isomers are formed for each metal complex. a. The Be2 complexes are tetrahedral. Draw the two isomers of Be(tfa)2. What type of isomerism is exhibited by Be(tfa)2? b. The Cu2 complexes are square planar. Draw the two isomers of Cu(tfa)2. What type of isomerism is exhibited by Cu(tfa)2? 83

Would it be better to use octahedral Ni2 complexes or octahedral Cr2 complexes to determine whether a given ligand is a strong-field or weak-field ligand by measuring the number of unpaired electrons? How else could the relative ligand field strengths be determined?

Name the following coordination compounds. a. Na4[Ni(C2O4)3] b. K2[CoCl4] c. [Cu(NH3)4]SO4 d. [Co(en)2(SCN)Cl]Cl

Give formulas for the following. a. Hexakis(pyridine)cobalt(III) chloride b. Pentaammineiodochromium(III) iodide c. Tris(ethylenediamine)nickel(II) bromide d. Potassium tetracyanonickelate(II) e. Tetraamminedichloroplatinum(IV) tetrachloroplatinate(II)

The equilibrium constant Ka for the reaction is 6.0  103 . a. Calculate the pH of a 0.10 M solution of Fe(H2O)6 3. b. Will a 1.0 M solution of iron(II) nitrate have a higher or lower pH than a 1.0 M solution of iron(III) nitrate? Explain.

Carbon monoxide is toxic because it binds more strongly to iron in hemoglobin (Hb) than does O2. Consider the following reactions and approximate standard free energy changes: Using these data, estimate the equilibrium constant value at 25C for the following reaction:

For the process what would be the expected ratio of cis to trans isomers in the product?

The complex trans-[NiA2B4] 2, where A and B represent neutral ligands, is known to be diamagnetic. Do A and B produce very similar or very different crystal fields? Explain.

Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is a. Without referring to Appendix 4, predict the sign of S for the preceding reaction. Explain. b. The spontaneity of the preceding reaction is temperature dependent. Predict the sign of Ssurr for this reaction. Explain. c. For Ni(CO)4(g), Hf  607 kJ/mol and S  417 J/K mol at 298 K. Using these values and data in Appendix 4, calculate H and S for the preceding reaction. d. Calculate the temperature at which G  0 (K  1) for the preceding reaction, assuming that H and S do not depend on temperature. e. The first step of the Mond process involves equilibrating impure nickel with CO(g) and Ni(CO)4(g) at about 50C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the preceding reaction at 50.C. f. In the second step of the Mond process, the gaseous Ni(CO)4 is isolated and heated at 227C. The purpose of this step is to deposit as much nickel as possible as pure solid (the reverse of the preceding reaction). Calculate the equilibrium constant for the above reaction at 227C. g. Why is temperature increased for the second step of the Mond process? 91. Conside

Consider the following data: where en  ethylenediamine. a. Calculate for the half-reaction b. Based on your answer to part a, which is the stronger oxidizing agent, Co3 or Co(en)3 3? c. Use the crystal field model to rationalize the result in part b.

Henry Taube, 1983 Nobel Prize winner in chemistry, has studied the mechanisms of the oxidationreduction reactions of transition metal complexes. In one experiment he and his students studied the following reaction: Chromium(III) and cobalt(III) complexes are substitutionally inert (no exchange of ligands) under conditions of the experiment. Chromium(II) and cobalt(II) complexes can exchange ligands very rapidly. One of the products of the reaction is Cr(H2O)5Cl2. Is this consistent with the reaction proceeding through formation of 1H as an intermediate? Explain.

Chelating ligands often form more stable complex ions than the corresponding monodentate ligands with the same donor atoms. For example, where en is ethylenediamine and penten is This increased stability is called the chelate effect. Based on bond energies, would you expect the enthalpy changes for the above reactions to be very different? What is the order (from least favorable to most favorable) of the entropy changes for the above reactions? How do the values of the formation constants correlate with S? How can this be used to explain the chelate effect?

Qualitatively draw the crystal field splitting of the d orbitals in a trigonal planar complex ion. (Let the z axis be perpendicular to the plane of the complex.)

Qualitatively draw the crystal field splitting for a trigonal bipyramidal complex ion. (Let the z axis be perpendicular to the trigonal plane.)

Sketch a d-orbital energy diagram for the following. a. a linear complex with ligands on the x axis b. a linear complex with ligands on the y axis

Sketch and explain the most likely pattern for the crystal field diagram for the complex ion trans-diamminetetracyanonickelate(II), where CN produces a much stronger crystal field than NH3. Explain completely and label the d orbitals in your diagram. Assume the NH3 ligands lie on the z axis.

a. Calculate the molar solubility of AgBr in pure water. Ksp for AgBr is 5.0  1013

b. Calculate the molar solubility of AgBr in 3.0 M NH3. The overall formation constant for Ag(NH3)2  is 1.7  107 , that is,

c. Compare the calculated solubilities from parts a and b. Explain any differences.

d. What mass of AgBr will dissolve in 250.0 mL of 3.0 M NH3?

e. What effect does adding HNO3 have on the solubilities calculated in parts a and b?

The ferrate ion, FeO4 2, is such a powerful oxidizing agent that in acidic solution, aqueous ammonia is reduced to elemental nitrogen along with the formation of the iron(III) ion. a. What is the oxidation state of iron in FeO4 2, and what is the electron configuration of iron in this polyatomic ion? b. If 25.0 mL of a 0.243 M FeO4 2 solution is allowed to react with 55.0 mL of 1.45 M aqueous ammonia, what volume of nitrogen gas can form at 25C and 1.50 atm?

a. In the absorption spectrum of the complex ion [Cr(NCS)6] 3, there is a band corresponding to the absorption of a photon of light with an energy of 1.75  104 cm1 . Given 1 cm1  1.986  1023 J, what is the wavelength of this photon?

b. The bond angle in [Cr(NCS)6] 3 is predicted to be 180. What is the hybridization of the N atom in the NCS ligand when a Lewis acidbase reaction occurs between Cr3 and NCS that would give a 180 bond angle? [Cr(NCS)6] 3 undergoes substitution by ethylenediammine (en) according to the equation Does [Cr(NCS)2(en)2]  exhibit geometric isomerism? Does [Cr(NCS)2(en)2]  exhibit optical isomerism?

Ammonia and potassium iodide solutions are added to an aqueous solution of Cr(NO3)3. A solid is isolated (compound A), and the following data are collected: i. When 0.105 g of compound A was strongly heated in excess O2, 0.0203 g CrO3 was formed. ii. In a second experiment it took 32.93 mL of 0.100 M HCl to titrate completely the NH3 present in 0.341 g compound A. iii. Compound A was found to contain 73.53% iodine by mass. iv. The freezing point of water was lowered by 0.64C when 0.601 g compound A was dissolved in 10.00 g H2O (Kf  1.86C kg/mol). What is the formula of the compound? What is the structure of the complex ion present? (Hints: Cr3 is expected to be sixcoordinate, with NH3 and possibly I as ligands. The I ions will be the counterions if needed.) 3

There are three salts that contain complex ions of chromium and have the molecular formula CrCl3  6H2O. Treating 0.27 g of the first salt with a strong dehydrating agent resulted in a mass loss of 0.036 g. Treating 270 mg of the second salt with the same dehydrating agent resulted in a mass loss of 18 mg. The third salt did not lose any mass when treated with the same dehydrating agent. Addition of excess aqueous silver nitrate to 100.0-mL portions of 0.100 M solutions of each salt resulted in the formation of different masses of silver chloride; one solution yielded 1430 mg AgCl; another, 2870 mg AgCl; the third, 4300 mg AgCl. Two of the salts are green and one is violet. Suggest probable structural formulas for these salts, defending your answer on the basis of the preceding observations. State which salt is most likely to be violet. Would a study of the magnetic properties of the salts be helpful in determining the structural formulas? Explain.