Ch 301 Exam 3 - Version – Exam 3 – Sutcliffe – 1 This...

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Unformatted text preview: Version – Exam 3 – Sutcliffe – ( 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Write the net ionic equation for this reac- tion occuring in water: Calcium sulfide and iron(II) bromide are mixed to form iron(II) sulfide and calcium bromide. 1. CaS + 2 Br − → S 2 − + CaBr 2 2. S 2 − + Fe 2+ → FeS correct 3. No reaction occurs. 4. Sr 2+ + S 2 − + Fe 2+ + 2 Br − → FeS + CaBr 2 5. S 2 − + FeBr 2 → FeS + 2 Br − 6. Ca 2+ + 2 Br − → CaBr 2 Explanation: 002 10.0 points What are the products of the following reac- tion? Sr(OH) 2 + 2 HNO 3 → 1. Sr(NO 2 ) 2 + 2 H 2 O 2 2. Sr(NO 3 ) 2 + 2 H 2 O correct 3. SrNO 3 + H 2 O 4. SrH 2 + HNO 5 Explanation: Sr(OH) 2 is a base and HNO 3 an acid; they create a salt and water. 003 10.0 points Which of the following, in the solid state, would be an example of a covalent crystal? 1. diamond correct 2. water 3. carbon dioxide 4. iron 5. barium fluoride Explanation: Covalent crystals are held together by co- valent bonds in an extended, rigid crystalline network. 004 10.0 points How much 0.100 M H 2 SO 4 are needed to make 25.0 mL of 0.00500 M solution? 1. 0.00200 mL 2. 0.800 mL 3. 500 mL 4. 1.25 mL correct Explanation: M 1 = 0.100 M M 2 = 0.00500 M V 2 = 25 . 0 mL A portion of the 0 . 1 M H 2 SO 4 solution will be diluted with water to form 25 mL of the . 005 M H 2 SO 4 solution. All of the moles of H 2 SO 4 in the new dilute solution must come from the more concentrated solution. (There is no H 2 SO 4 in the water!) We use the desired volume and molarity of the dilute solution to determine the number of moles of H 2 SO 4 needed to make this solution: ? mol H 2 SO 4 = 25 mL soln × 1 L soln 1000 mL soln × . 005 mol H 2 SO 4 1 L soln = 0 . 000125 mol H 2 SO 4 We need enough of the 0 . 1 M solution to provide 0 . 000125 mol H 2 SO 4 . We use the molarity to convert from moles to volume of the solution: Version – Exam 3 – Sutcliffe – 2 ? mL soln = 0 . 000125 mol H 2 SO 4 × 1 L soln . 1 mol H 2 SO 4 × 1000 mL soln 1 L soln = 1 . 25 mL soln 1 . 25 mL of the 0 . 1 M solution diluted to 25 mL with water would give us the desired solution. 005 10.0 points If a sample of gas is heated from 100 ◦ C to 300 ◦ C at constant pressure, the volume will ? by a factor of ? . 1. increase; about three 2. No other answer is correct, because the volume cannot change when the pressure is constant. 3. increase; about 1.5 correct 4. decrease; about 1.5 5. decrease; about three Explanation: T 1 = 100 ◦ C + 273 = 373 K T 2 = 300 ◦ C + 273 = 573 K The temperature increases by a factor of 573 373 = 1 . 5. According to Charles’ Law, the volume of the gas would increase by the same factor....
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This note was uploaded on 11/15/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Ch 301 Exam 3 - Version – Exam 3 – Sutcliffe – 1 This...

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