Practice3ans

Practice3ans - Practice Questions (with answers) Quiz #3...

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Practice Questions (with answers) Quiz #3 material 1. Element X forms compounds with chlorine that have the formulae XCl 2 and XCl 4 . A 10.0 g sample of XCl 2 reacts with excess Cl 2 to form 12.55 g of XCl 4 . What is element X? a. Am b. Pb c. Rh d. Bi e. None of the above 2. Scandium (Sc) reacts with HCl to form Sc x Cl y and H 2 : x Sc + y HCl b Sc x Cl y + ( y /2) H 2 If 2.25 g Sc react with excess HCl and 0.1502 g of H 2 are produced, what is the empirical formula of Sc x Cl y ? a. Sc 2 Cl 3 b. Sc 4 Cl 3 c. ScCl 2 d. ScCl 3 e. None of the above
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3. The “rusting” of iron is actually the formation of iron oxides (Fe x O y ) by the reaction of Fe with O 2 . A pure iron bar is placed on a balance and the balance indicates that its mass is 75.0 g. As the iron bar rusts, which of the following is/are true? I. The balance will read less than 75.0 g. II. The balance will read 75.0 g. III. The balance will read greater than 75.0 g. IV. The balance will read less than 75.0 g, but if the bar is removed, the rust scraped off, and the bar replaced, the balance will read 75.0 g. V. The balance will read greater than 75.0 g, but if the bar is removed, the rust scraped off, and the bar replaced, the balance will read 75.0 g. a. I only b. II only c. III only d. Both I and IV e. Both III and V 4. Which of the following best describes the conservation of mass in nuclear and chemical reactions? a. In nuclear reactions, mass is not constant, but in chemical reactions mass is effectively constant. b. In nuclear reactions, mass is effectively constant, but in chemical reactions mass is not constant. c. In both nuclear and chemical reactions, mass is not constant, but for nuclear reactions the change in mass is small enough to be neglected. d. In both nuclear and chemical reactions, atoms are neither created nor destroyed. e. In both nuclear and chemical reactions, neither energy nor mass are conserved.
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5. Consider the following balanced equation: 3X + 3Y b 3Z If 5.0 g of X reacts with 4.0 g of Y, which of the following must be true? a. Because the stoichiometric ratio of X to Y to Z is 1 : 1 : 1, we can conclude that B is the limiting reagent. b. Because the stoichiometric ratio of X to Y to Z is 1 : 1 : 1, we can conclude that A is the limiting reagent. c. Because the stoichiometric ratio of X to Y to Z is 1 : 1 : 1, we can conclude that 4.0 g of C are produced. d. Both a and c e. None of the above 6. Styrene is a molecule made of only carbon and hydrogen. If styrene is reacted with excess O 2 to make 1.481 g of CO 2 and 0.303 g H 2 O, what is its empirical formula? a. CH 2 b. C 2 H c. CH d. C 2 H 2 e. None of the above
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7. Titanium tetrachloride (TiCl 4 ) reacts with water to form titanium dioxide and hydrochloric acid according to the following unbalanced equation: TiCl 4 + H 2 O b TiO 2 + HCl What mass of H 2 O is required to react completely with 0.1277 moles of TiCl 4 ? a. 4.6 g
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This note was uploaded on 11/03/2009 for the course CHEM 1403 taught by Professor Leornardfine during the Fall '07 term at Columbia.

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Practice3ans - Practice Questions (with answers) Quiz #3...

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