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Unformatted text preview: silva (jrs4378) Sample Exam Two Shear (52375) 1 This print-out should have 34 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Which one of the following formulas is wrong? 1. sodium sulfate : Na 2 SO 4 2. sodium nitrate : NaNO 3 3. potassium chloride : KCl 4. calcium sulfate : CaSO 4 5. ammonium perchlorate : NH 4 ClO 3 cor- rect Explanation: The ammonium ion is NH + 4 ; the perchlor ate ion is derived from perchlor ic acid (HClO 4 ) and has the formula ClO 4 . One ClO 4 is needed to balance the charge on each NH + 4 , so the formula for ammonium perchlorate is NH 4 ClO 4 . The sodium ion is Na + ; the sulfate ion is SO 2 4 . Two Na + are needed to balance the charge on each SO 2 4 , so the formula for sodium sulfate is Na 2 SO 4 . The sodium ion is Na + ; the nitrate ion is NO 3 . One NO 3 is needed to balance the charge on each Na + , so the formula for sodium nitrate is NaNO 3 . The potassium ion is K + ; the chloride ion is Cl . One K + is needed to balance the charge on each Cl , so the formula for potassium chloride is KCl. The calcium ion is Ca 2+ ; the sulfate ion is SO 2 4 . One Ca 2+ is needed to balance the charge on each SO 2 4 , so the formula for calcium sulfate is CaSO 4 . 002 10.0 points Give the formula for sodium nitrate. 1. Na(NO) 3 2. Na 3 NO 3 3. Na(NO 3 ) 2 4. NaNO 3 correct Explanation: The sodium ion is Na + ; the nitrate ion is NO 3 . One Na + is needed to balance the charge of each NO 3 , so the formula is NaNO 3 . 003 10.0 points Calcium metal reacts with water to form cal- cium hydroxide and hydrogen gas. How much hydrogen is formed when 0.50 g of calcium are added to water? 1. 0.10 g 2. 0.025 g correct 3. 0.050 g 4. 0.50 g Explanation: m Ca = 0 . 50 g The balanced equation is Ca + 2 H 2 O Ca(OH) 2 + H 2 , and indicates the 1 mol H 2 is produced for each mole Ca reacted. First we calculate moles Ca present: ? mol Ca = 0 . 50 g Ca 1 mol Ca 40 . 1 g Ca = 0 . 0125 mol Ca Since 1 mol H 2 is produced for each mole Ca reacted, 0.0125 mol H 2 would be produced from 0.0125 mol Ca. The molar mass of H 2 is used to convert to grams H 2 : ? g H 2 = 0 . 0125 mol H 2 2 g H 2 1 mol H 2 = 0 . 025 g H 2 004 10.0 points Fluorine is more electronegative than oxygen because 1. the outer orbitals of oxygen are located silva (jrs4378) Sample Exam Two Shear (52375) 2 closer to the nucleus than the outer orbitals of fluorine. 2. the outer orbitals of fluorine are located further from the nucleus than the outer or- bitals of oxygen. 3. False; oxygen is more electronegative than fluorine....
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This note was uploaded on 08/29/2010 for the course CH 52375 taught by Professor Ruth during the Spring '09 term at University of Texas at Austin.
- Spring '09