HW 2 & 3 A-answers

HW 2 & 3 A-answers - Cheung, Anthony – Stoich 1 –...

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Unformatted text preview: Cheung, Anthony – Stoich 1 – Due: Oct 28 2006, midnight – Inst: McCord 1 This print-out should have 20 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 Cobalt(III) oxide would be the label for 1. Co 3 O. 2. CoO 3 . 3. CoO. 4. Co 3 O 2 . 5. Co 2 O 3 . correct Explanation: The cobalt(III) ion is Co 3+ ; the oxide ion is O 2- . Three O 2- are needed to balance the charge of every two Co 3+ . (This gives a total cation charge of +6 and a total anion charge of- 6.) The formula is Co 2 O 3 . 002 (part 1 of 1) 10 points Give the formula for aluminum hydroxide. 1. AlOH 2. Al(OH) 3 correct 3. AlOH 3 4. AlH 3 Explanation: The aluminum ion is Al 3+ ; the hydroxide ion is OH- . Three OH- are needed to balance the charge of each Al 3+ , so the formula is Al(OH) 3 . 003 (part 1 of 1) 10 points How many hydrogen atoms appear in the for- mula of ammonium sulfate? 1. 8 atoms correct 2. 10 atoms 3. 6 atoms 4. 4 atoms 5. 2 atoms Explanation: The ammonium ion is NH + 4 and the sulfate ion is SO 2 4- . Two NH + 4 are needed to balance the charge on each SO 2- 4 . The formula is (NH 4 ) 2 SO 4 . 004 (part 1 of 1) 10 points What is the correct formula for copper(II) nitrate? 1. CuN 2 2. Cu(NO 3 ) 2 correct 3. Cu(NO 2 ) 2 4. Cu 2 NO 2 5. CuNO 3 6. Cu 2 N 7. Cu 2 NO 3 8. CuNO 2 Explanation: The copper(II) ion is Cu 2+ ; the nitrate ion is NO 1- 3 . We need twice as many NO 1- 3 as Cu 2+ to equalize the charge, so the ratio of copper(II) to nitrate ions is 1:2 and the for- mula for copper(II) nitrate is Cu(NO 3 ) 2 . 005 (part 1 of 1) 10 points Which compound has the wrong chemical for- mula? 1. Ba 3 (PO 4 ) 2 2. Mg(OH) 2 3. CaOH correct Cheung, Anthony – Stoich 1 – Due: Oct 28 2006, midnight – Inst: McCord 2 4. (NH 4 ) 2 SO 4 Explanation: The calcium ion is Ca 2+ ; the hydroxide ion is OH- . Two OH- are needed to balance the charge of each Ca 2+ , so the formula is Ca(OH) 2 . The magnesium ion is Mg 2+ ; the hydroxide ion is OH- . Two OH- are needed to balance the charge of each Mg 2+ , so the formula is Mg(OH) 2 . The barium ion is Ba 2+ ; the phosphate ion is PO 3- 4 . Two PO 3- 4 are needed to balance the charge of every three Ba 2+ . (This gives a total anion charge of- 6 and a total cation charge of +6.) The formula is Ba 3 (PO 4 ) 2 . The ammonium ion is NH + 4 ; the sulfate ion is SO 2- 4 . Two NH + 4 are needed to balance the charge of each SO 2- 4 , so the formula is (NH 4 ) 2 SO 4 ....
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This note was uploaded on 03/09/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas.

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HW 2 & 3 A-answers - Cheung, Anthony – Stoich 1 –...

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