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1178564733Xuj - Anderson Kiel Homework 9 Due midnight Inst...

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Anderson, Kiel – Homework 9 – Due: Apr 17 2007, midnight – Inst: McCord 1 This print-out should have 34 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points What is the oxidation number for H in the compound NaH? 1. 0 2. - 1 correct 3. Cannot be determined 4. +2 5. +1 Explanation: NaH is a metal hydride. Group IA elements always have an oxidation number of +1 with no exceptions. Na has an oxidation number of +1, therefore H must have an oxidation number of - 1. 002 (part 1 of 1) 10 points In the redox conversion of Ni 2+ to NiO 4 - , the oxidation number of Ni goes from ( - 2, 0, +2) to ( - 1, +1, +7, +9). Recall that the oxidation number of oxygen is typically - 2. 1. +2; +7 correct 2. 0; +9 3. +2; - 1 4. - 2; +9 5. - 2; +7 6. - 2; +1 7. +2; +9 8. 0; +1 9. 0; +7 Explanation: Oxidation numbers are per atom. The oxi- dation number of a monatomic ion is equal to the charge on the ion. Nickel in Ni 2+ has an oxidation number of +2. The sum of oxida- tion numbers in a polyatomic ion is equal to the charge on the ion. We set the sum of the oxidation numbers in NiO - 4 equal to - 1 and solve for the oxidation number of Ni: x + 4( - 2) = - 1 NiO - 4 : x = +7 003 (part 1 of 2) 10 points Name the compound SO 3 . 1. sulfur trioxide correct 2. sulfur dioxide 3. oxysulfur 4. sulfuric acid 5. sulfur oxide Explanation: SO 3 is sulfur trioxide 004 (part 2 of 2) 10 points Assign oxidation numbers to each atom in SO 3 . 1. S = +6, O = - 2 correct 2. S = +4, O = - 2 3. S = +1, O = - 2 4. S = +5, O = - 1 5. S = +2, O = - 2 Explanation: oxidation numbers = ? According to rule 4, O has an oxidation number of - 2: S - 2 O 3
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Anderson, Kiel – Homework 9 – Due: Apr 17 2007, midnight – Inst: McCord 2 The total oxidation number of the oxygen atoms is - 2 × 3 = - 6: S - 2 O 3 -→ S - 2 O 3 - 6 Balance the oxidation numbers: S +6 - 2 O 3 - 6 -→ +6 S +6 - 2 O 3 - 6 S therefore has an oxidation number of +6: S = +6 , O = - 2 005 (part 1 of 1) 10 points What is the oxidation number of carbon in carbonate? 1. 0 2. +1 3. +4 correct 4. -2 5. -3 6. -1 7. -4 8. +3 9. +2 Explanation: 006 (part 1 of 1) 10 points Assign oxidation numbers to each atom in MnO - 4 . 1. Mn = +1, O = - 2 2. Mn = +3, O = - 1 3. Mn = - 2, O = +2 4. Mn = +5, O = - 2 5. Mn = +7, O = - 2 correct Explanation: oxidation numbers = ? According to rule 4, O has an oxidation number of - 2 : Mn - 2 O - 4 The total oxidation number of the oxygen atoms is - 2 × 4 = - 8 : Mn - 2 O - 4 -→ Mn - 2 O - 4 - 8 Balance the oxidation numbers: Mn +7 - 2 O - 4 - 8 -→ +7 Mn +7 - 2 O - 4 - 8 Mn therefore has an oxidation number of +7: Mn = +7 , O = - 2 007 (part 1 of 1) 10 points Determine the oxidation state of the metal in [Cu(NH 3 ) 4 ](OH) 2 . 1. Cu = +4 2. Cu = +3 3. Cu = +5 4. Cu = +2 correct 5. Cu = +1 Explanation: Oxidation state of copper = ? Because NH 3 has no net charge, and OH has an oxidation number equal to its ionic charge of –1, Cu must have an oxidation number of +2. 008 (part 1 of 1) 10 points What is the oxidation number of the element Br in the compound BrF + 3 ?
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