Chemistry 151 Quiz 6-1 Week starting Nov. 5, 1997

Transcription

1 Chemistry 151 Quiz (4 pts) Which statement about the preparation of the halogens is CORRECT? (a) Cl 2 (g ) can oxidize Br 1- (aq )tobr 2 (aq ) and I 1- (aq )toi 2 (aq ). (b) F 2 (g ) can be prepared by Cl 2 (g ) oxidation of the CsF( ). (c) Cl 2 (g ) is prepared commercially by electrolysis of NaCl( ). (d) F 2 (g ) can be prepared by electrolysis of KF(aq ). 2. (3 pts) Which species probably CANNOT be prepared? (a) ClF 3 (b) IF 7 (c) Br 2 Cl 5 (d) ICl (4 pts) Which equation is an example of a Lewis acid-base reaction? (a) XeF 4 (g )+H 2 O(g ) XeOF 2 (g ) + 2 HF(g ) (b) XeF 2 (g ) + SbF 5 [XeF][SbF 6 ] (c) Cl 2 ( ) + Ca(OH) 2 (aq ) CaCl(OCl)(aq )+H 2 O (d) 4 KClO 3 + heat KCl(s ) + 3 KClO 4 (s ) 4. (4 pts) Which statement about the reaction of Cl 2 (g ) with HI(g )iscorrect? (a) Cl 2 (g ) doesn t react with HI(g ). (b) Cl 2 (g ) oxidizes the HI(g )toi 2 (s ), also producing HCl(g ). (c) No I 2 (g ) is produced in this reaction; the products are ICl(g ) and HCl(g ). (d) Some I 2 (g ) and ICl(g ) are produced, but the final product is I 2 Cl 6 ().

2 Chemistry 151 Quiz (4 pts) Which equation is an example of a disproportionation reaction? (a) XeF 4 (g )+H 2 O(g ) XeOF 2 (g ) + 2 HF(g ) (b) XeF 2 (g ) + SbF 5 [XeF 2 ][SbF 6 ] (c) Cl 2 ( ) + Ca(OH) 2 (aq ) CaCl(OCl)(aq )+H 2 O MnO 2, (d) 2 KClO KCl(s )+3O 2 (g) 2. (3 pts) Identify the correct formula of barium chlorite. (a) BaClO 2 (b) Ba(ClO 3 ) 2 (c) Ba(ClO) 2 (d) Ba(ClO 2 ) 2 3. (4 pts) Which reaction is likely to result in the successful conversion of La 2 O 3 (s) to LaCl 3 (s)? (a) La 2 O 3 (s) + 6Cl 2 (g) 2 LaCl 3 (s) +3Cl 2 O(g). (b) La 2 O 3 (s) + 3 COCl 2 (g) 2 LaCl 3 (s) +3CO 2 (g). (c) La 2 O 3 (s) + 6 NaCl (s) 2 LaCl 3 (s) +6Na 2 O. (d) La 2 O 3 (s) + 6 HCl(aq ) 2 LaCl 3 (s) +3H 2 O( ). 4. (4 pts) Which statement about d-block chemistry is CORRECT? (a) CrO (s) isamore acidic than CrO 3. (b) Because of the 'lanthanide contraction,' 5d elements are more dense than 4d elements. (c) Ti 3+ is a smaller ion than Fe 3+. (d) The 3d element that shows the highest oxidation state is Fe.

3 Chemistry 151 Quiz (4 pts) Which statement about the lanthanide contraction is CORRECT? (a) It causes the 5f elements to have more oxidation states than the 4f elements. (b) It causes the atomic radius of Hf to be slightly smaller than that of Zr. (c) It causes La to be slightly larger than Y. (d) It causes La 3+ to be more acidic than Lu (4 pts) Which statement about d-block elements is CORRECT? (a) (b) (c) (d) 5d-block elements are more dense than 4d-block elements. 4d-block elements are less dense than 3d-block elements. Few of the 3d-block ions are paramagnetic. In general, d-block elements are softer than main-group elements. 3. (3 pts) The name of the compound whose formula is KBrO 3 is (a) potassium bromite (b) potassium perbromate (c) potassium hypobromite (d) potassium bromate 4. (4 pts) Many aqueous solutions of 3d-block ions are colored because (a) (b) (c) (d) they have lots of unpaired electrons. the d electrons are excited to higher energy levels by thermal energy and emit light when they return to the ground state. solvent molecules surrounding the ions cause two of the 3d orbitals to become separated from the other three by energies in the visible region of the spectrum. d electrons can be excited by photons in the visible region of the spectrum to the surrounding solvent molecules.

4 Chemistry 151 Quiz (4 pts) Which statement about the lanthanide contraction is CORRECT? (a) It causes the 4f elements to have more oxidation states than the 5f elements. (b) It causes the atomic radius of Zr to be slightly smaller than that of Hf. (c) It causes La 3+ to be smaller than Lu 3+. (d) It causes Lu 3+ to be more acidic than La (4 pts) When Cl 2 (g ) is bubbled into a LiOH(aq ) solution, the expected products are (a) LiCl, LiOCl, and H 2 O (b) LiCl, LiOCl, and OH 1- (c) LiCl and H 2 O (d) LiOCl and H 2 O 3. (3 pts) The oxidation state of Xe in XeOF 4 is (a) 0 (b) 2+ (c) 4+ (d) (4 pts) Which statement about the vanadium multiple oxidation states is CORRECT? (a) Vanadium has four (4) oxidation states: 1+, 3+, 5+, 6+. (b) In its highest two oxidation states vanadium is combined with oxygen as oxoanions. (c) Sheldon used mercury, Hg, as the reducing agent. (d) The colors resulted when electrons fell from higher energy levels to the ground level.

5 Chemistry 151 Quiz (4 pts) Which statement about the lanthanide contraction is CORRECT? (a) It causes all the 4f elements to have the same oxidation state. (b) It means that the nuclear radius decreases as one progresses from La to Lu. (c) It causes the 5d elements to be much more dense than the 4d elements. (d) It causes Lu 3+ to be more basic than La (4 pts) The ground state electron configuration of Fe 3+ is (a) [Ar] 3d 6 4s 2 (b) [Ar] 3d 3 4s 2 (c) [Ar] 3d 6 4s 0 (d) [Ar] 3d 5 4s 0 3. (3 pts) Which compound is expected to be diamagnetic? (a) ZnCl 2 (b) FeCl 3 (c) CuCl 2 (d) VCl 3 4. (4 pts) Which statement about the demonstrations that involved chromium (Cr) iscorrect? (a) In the Cr 2 O 2-7 -H 2 O 2 demonstration H 2 O 2 acts as the oxidizing agent. (b) A strong acid changes the CrO 2-4 ion to the Cr 2 O 2-7 ion. (c) In an acidic medium the Cr 2 O 2-7 ion behaves as a reducing agent. (d) 2- In the Cr 2 O 7 -H 2 O 2 demonstration the solution color changed from the orange of the dichromate ion through green to the blue of the Cr 3+ ion.

6 Chemistry 151 Quiz (4 pts) Which statement about the lanthanide contraction is CORRECT? (a) (b) (c) (d) Electrons added to the 4f energy level are not completely screened from the increasing nuclear charge, so the electron cloud contracts. It means that the nuclear radius decreases as one progresses from La to Lu. It causes the 5d elements to be less dense than the 4d elements. It causes the acidity of the 4f ions to decrease as the size of the element decreases. 2. (4 pts) Which reaction can be classified as a Lewis acid/base reaction? (a) NaOH(aq )+HC 2 H 3 O 2 (aq ) H 2 O + NaC 2 H 3 O 2 (aq ) (b) Xe(g )+F 2 (g ) XeF 2 (g ) (c) ClF 3 (g ) + AsF 5 (g ) [ClF 2 ][AsF 6 ] (d) Cl 2 (g ) + 2 KOH(aq ) KOCl(aq ) + KCl(aq )+H 2 O 3. (3 pts) Which species is UNLIKELY to be stable? (a) BrF 3 (b) IF 5 1- (c) I 2 Cl 6 (d) KClO 2 4. (4 pts) Sodium hydrogen sulfite, NaHSO 3, is added to a neutral permanganate ion solution. In the reaction that follows, the permanganate ion will be reduced to (a) MnO 2 (s ) (b) MnO 4 1- (aq ) (c) MnO 4 2- (aq ) (d) Mn 2+ (aq )

7 Chemistry 151 Quiz (4 pts) Sodium hydrogen sulfite, NaHSO 3, is added to an acidic permanganate ion solution. In the reaction that follows, the permanganate ion will be reduced to (a) MnO 2 (s ) (b) MnO 4 1- (aq ) (c) MnO 4 2- (aq ) (d) Mn 2+ (aq ) 2. (3 pts) Which oxide is expected to be an oxidizing agent? (a) Ti 2 O 3 (b) VO (c) MnO 2 (d) NiO 3. (4 pts) Which oxide is expected to be most acidic? (a) TiO 2 (b) CrO 3 (c) CoO (d) Fe 2 O 3 4. (4 pts) Which list contains the oxidation states Sheldon demonstrated for vanadium? (a) 2+, 3+, 4+, 5+ (b) 1+, 2+, 3+, 4+, 5+ (c) 1+, 2+, 4+, 5+ (d) 2+, 3+, 5+

8 Chemistry 151 Quiz (4 pts) Sodium hydrogen sulfite, NaHSO 3, is added to a basic permanganate ion solution. In the reaction that follows, the permanganate ion will be reduced to (a) MnO 2 (s ) (b) MnO 4 1- (aq ) (c) MnO 4 2- (aq ) (d) Mn 2+ (aq ) 2. (4 pts) Identify the CORRECT statement. (a) (b) (c) (d) The melting points of transition metals are about the same as those of main group metals. Most transition metals are harder than main group metals. Aqueous solutions of most main group and all transition group ions are colored. In general, main group metals exhibit more oxidation states than transition metals. 3. (4 pts) Arrange the transition metals, Ti, Ni, Mn, and La in order of increasing atomic radii (smallest first). (a) La<Ti<Mn<Ni (b) La<Ni<Ti<Mn (c) La<Mn<Ni<Ti (d) Ni<Mn<Ti<La 4. (3 pts) The ground state electron configuration of Cr 3+ is (a) [Ar] 3d 3 4s 0 (b) [Ar] 3d 2 4s 0 (c) [Ar] 3d 1 4s 2 (d) [Ar] 3d 4 4s 1

9 Chemistry 151 Quiz (4 pts) Which reaction is most likely to occur as written? (a) Xe(g )+Cl 2 (g ) XeCl 2 (g ) (b) Xe(g )+2F 2 (g ) XeF 4 (g ) (c) Xe(g )+O 2 (g ) XeO 2 (s ) (d) Br 2 ( )+3I 2 2 BrI 3 (s ) 2. (4 pts) Which statement about transition metal chemistry is CORRECT? (a) Like aluminum, chromium forms a thin, dense oxide coating that protects it from further oxidation. (b) Iron in the presence of oxygen will always rust, i.e., change to Fe 2 O 3 (s ). (c) Tin protects iron from oxidation by making it the anode of an electrochemical cell. (d) Galvanized iron or steel is made by dipping the metal in molten tin. 3. (3 pts) In the reaction, CsF(s ) + BrF 3 () Cs[BrF 4 ], BrF 3 may be considered a (a) Lewis base (b) oxidizing agent (c) Lewis acid (d) reducing agent. 4. (4 pts) In the demonstration in which HI(g ) was mixed with Cl 2 (g ), (a) the HI was the oxidizing agent. (b) I 2 (g ), an intermediate product, was ultimately converted to ClI 3 (s ). (c) dimeric I 2 Cl 6 formed, suggestive that ICl 3 is a strong Lewis acid. (d) dimeric I 2 Cl 6 formed, suggestive that ICl 3 is a strong Lewis base.

10 Chemistry 151 Quiz (4 pts) In the space at the right of the answer sheet sketch the structure of I 2 Cl (4 pts) Which equation best illustrates a hydrolysis reaction? (a) HI(g )+H 2 O H 3 O + (aq )+I 1- (aq ) (b) V(NO 3 ) 3 (s ) +6H 2 O V(OH 2 ) 3+ 6 (aq )+ 3NO 1-3 (aq ) (c) XeF 6 (g )+2H 2 O(g ) XeO 2 F 2 (s )+4HF(g ) (d) Cl 2 O+H 2 O 2 HOCl(aq ) 3. (3 pts) The name of the compound whose formula is HClO 2 is (a) hypochlorous acid (b) chlorous acid (c) chloric acid (d) perchloric acid 4. (4 pts) It is possible to change the Cr 2 O 7 2- ion to the CrO 4 2- ion by addition of (a) H 2 SO 4 (aq ) (b) H 2 O 2 (aq ) (c) NaOH(aq ) (d) H 3 PO 4 (aq ) and H 2 O 2 (aq )

11 Chemistry 151 Quiz (4 pts) Use VSEPR to determine the molecular structure of XeF 4 (g). Based upon its structure, the hybridization of the Xe orbitals must be: (a) sp 3 (b) dsp 3 (c) d 2 sp 3 (d) dsp 2 2. (4 pts) Which statement about the corrosion of iron is CORRECT? (a) A tin coating makes iron the cathode of an electrochemical cell, protecting it from corrosion. (b) Galvanized steel has a thin coating of tin on the surface of the steel. (c) Although zinc is very reactive, it self-protects by forming something like a Zn 2 (OH) 2 CO 3 coating. (d) Corrosion of iron requires only exposure to O 2 (g). 3. (3 pts) The ground state electron configuration of the Mn ion in MnO 2 (s) is (a) [Ar] 3d 3 (b) 3d 1 4s 2 (c) 3d 9 4s 2 (d) 3d 5 4. (4 pts) Which statement about titanium chemistry is CORRECT? (a) At room temperature TiCl 4 is a white solid. (b) Titanium is a very soft metal, much like aluminum. (c) The principal oxidation state of titanium is 2+. (d) TiCl 4 reacts with moisture in the air to give a white smoke and HCl (g).