DESCRIPTIVE INORGANIC CHEMISTRY April 2, 2013 INSTRUCTIONS: PRINT YOUR NAME > NAME.

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1 DESCRIPTIVE INORGANIC CHEMISTRY QUIZ III April 2, 2013 INSTRUCTIONS: PRINT YOUR NAME > NAME. SHOW YOUR WORK FOR PARTIAL CREDIT THERE IS A PERIODIC TABLE AND A TABLE OF BOND ENERGIES ATTACHED THE LAST PAGES ARE a Table of Bond energies and A Periodic Table Work 5 of these (20 pts each) R = lit-atm/mol-k 1 (20) R = J/mol-K 2 (20) h = X J-s 3 (20) c = X 10 8 m/s 4 (20) J = (kg-m 2 )/s 2 5 (20) 6 (20) 7 (20) l TOTAL(100)

2 1. Given the following data, construct the Born-Haber cycle to estimate the Enthalpy of formation for NaH from Na(s) and H 2 (g). Bond energies are in an attached appendix. (Remember this is for formation of one mole of the NaH) (Caution: I have included some irrelevant data in the table.) Enthalpy Values kj/mol Na atomization st electron affinity of Na st ionization of Na nd ionization of Na st Electron affinity of H -73 1st Ionization energy of H Estimated lattice energy NaH -808

3 2. Given that the enthalpy of atomization of one mole of S is +227 kj/mol, That is 1/8S 8 (s) S(g) ΔH = +227 kj/mol. Estimate the enthalpy of formation of SF 6 (one mole) from S 8 (s) and F 2 (g) using a diagram like a Born-Haber cycle. Bond energies are listed in a table at the back of the quiz. 3. (a) Classify the bonding in the highest oxidation number main group oxides fluorides of the 4th period as ionic, network, or covalent. All melting points are in C KO 2 CaO Ga 2 O 3 GeO 2 As 2 O 5 SeO 3 BrO (b) Why does the melting point increase in going from KO 2 to CaO? (c) Ga 2 O 3 might be expected to have a higher melting point than CaO, but it is lower. What is a possible explanation for this lower than expected value?

4 4. Answer the following concerning acid base theory Which is the stronger acid and explain your answer in (a) and (b) (a) H-ClO H ClO 2 (c) Ca 2+ (aq) Al 3+ ( aq) Which is the stronger base and explain your answer in (c), (d), and (e) (c) ClO - (aq) ClO 3 - (aq) (d) ClO 3 - CO 3 2- (e) O 2- I - (f)write the equation for the weak acid HClO 2 reacting as a Brønsted-Lowry acid towards water. (g) Write the equation for the base CN - reacting as a Brønsted-Lowry base towards water. (h) Identify the Lewis acid and the Lewis base in the following reaction. Explain your choice. 2CN - (aq) + Ag + (aq) Ag(CN) 2 - (aq) (i and j)mgo is a basic oxide, and CrO 3 is an acidic oxide with water. Write two separate equations for these oxides reactiing with water

5 5. (a) For the reaction shown in (b), assign oxidation numbers to N and S in each compound or ion. Identify which species is oxidized and which is reduced. NO 3 - (aq) N oxidation number NO(aq) N oxidation number SO 2 (aq) S oxidation number SO 4 2- (aq) S oxidation number Species reduced Species oxidized (b) Balance the following redox equation in acidic solution by the method of half reactions. Show your work. NO 3 - (aq) + SO 2 (aq) NO(aq) + SO 4 2- (aq)

6 6. (a) Which of the following would you expect to be the harder acid according to hard/soft-acid/base theory in each pair. Ag+ or Li + Co 3+ or Ni 2+.(b) Which of the following would you expect to be the harder base according to hard/soft acid/base theory in each pair O 2- or S 2 - SCN - or OH - (SCN- bonding through the S atom) (b) In the following aqueous solution equilibria, will the products or the reactants be favored? Explain your reasoning. AuCl - 2 (aq) + 2CN - (aq) Au(CN) - 2 (aq) + 2Cl - (aq) (c) Is the following reaction likely to occur in the gas phase? Give your reasons why. 3HgF 2 (g) + 2CoBr 3 (g) 3 HgBr 2 (g) + 2CoF 3 (g) (d) Heavier metals ions like Hg 2+ and Pb 2+ or Cd 2+ bind to enzymes and deactivate them. Would you expect these ions to bind to oxygen or sulfur rich sites in enzymes? Explain your choice.

7 7. (a)with which element do you expect to Cd to have a knight s move relationship? What are the oxidation states of the two metals? Describe the effect that that is used to explain the knight s move relationship. (b) When magnesium nitrates and sulfate are crystallized from water the crystals that come out are Mg(NO 3 ) 2 6H 2 O and MgSO 4 7H 2 O, respectively. Identify the d-block metal that forms a nitrate and a sulfate with the same number of water molecules in the formulas, and also have similar crystal structures. (c) Pick two elements from the periodic table that have a diagonal relationship. Name two facts that illustrate this relationship. What explains the similarity in properties of these two elements? (d) What are three pairs of combo elements that can replace Ge as a semiconductor? What is an advantage of using these substitution elements? (e) Describe how strontium from radioactive fallout can be detrimental to living systems.

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