a. There are 36 electrons in this element s ion that has a charge of +2. c. There are 10 electrons in the ion that has a charge of -1.

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1 NAME Sec 11am 1:30pm PH-218 EXAM II Friday, March 10, 2006 I SHORT ANSWER 1. (2 pts each) Using the periodic chart, identify the element that is described by each statement below a. There are 36 electrons in this element s ion that has a charge of +2. b. There are 47 electrons in the neutral atom. c. There are 10 electrons in the ion that has a charge of -1. d. In Group VB and Period 6 e. Its atomic number is 16 f. An atom in group VIB that forms a positive ion g. A nonmetal in period 4 2. Match the descriptions on the left with the items on the right. Items may be used more than once or not at all. Some blanks may have more than one answer, but only one is needed. (2 pts each). a. has a ph of 2 A. H 2 O b. neutral B. H 2 SO 4 c. tastes sour C. KOH d. feels slippery D. a salt e. turns red litmus to blue f. can neutralize HCl 3. (16 pts) Fill in the blanks or answer the questions. a. Assume that elements with atomic numbers greater than 106 will eventually be made. If so, what would be the atomic number of the next nonmetal? b. How many protons are in the atom of the diatomic element in Group V? c. The total number of atoms present in one unit of Ca3(PO4)2 is 1

2 d. What is the total number of hydrogen atoms present in Pb(OH) 2 (C 2 H 3 O 2 ) 2? e. What are valance electrons? f. In the electron configuration of a chromium (Cr #24) atom, there are valance electrons. g. Draw the electron dot structure for: the sulfur atom the sulfur ion i. has neutrons. II MULTIPLE CHOICE Place an x across the letter corresponding to the answer for each question (3 pts each). 4. a b c d 10. a b c d 5. a b c d 11. a b c d 6. a b c d 12. a b c d 7. a b c d 13. a b c d 8. a b c d 14. a b c d 9. a b c d 15. a b c d 4. Which statement about an atom is FALSE? a. The nucleus is the center region of an atom. b. Electrons are found outside the nucleus. c. The nucleus accounts for a small portion of the mass of an atom. d. The number of electrons are equal to the number of protons. 5. Elements constituting a period in the periodic table a. have similar chemical properties b. are called metals c. have consecutive atomic numbers d. will always be in the same group 6. Element X is a conductor of heat and electricity. X is also most likely a. dull and brittle c. element # 35 b. element # 10 d. malleable 2

3 7. The atomic weight of an atom with 39 electrons, 50 neutrons and 39 protons would most likely be a c b d Which of the following statements about the noble gases is incorrect? a. All exist in nature as individual atoms rather than molecules b. They are the most unreactive of all gases. c. All have very stable electron arrangements. d. All have 8 valence electrons. 9. According to the law of definite proportions, if a sample of a compound contains 7.00 grams of sulfur and 3.50 grams of oxygen, then another sample of the same compound which contains 14.0 grams of sulfur must contain a g of oxygen b g of oxygen c g of oxygen d g of oxygen 10. Which option will correctly fill in the blank to define the octet rule? Atoms will electrons so each atom involved will have a noble gas configuration. a. share b. lose c. lose or gain d. lose, gain or share 11. Which of the following elements is represented by a diatomic molecule in a chemical equation? a. chlorine (#17) b. beryllium (#4) c. krypton (#36) d. boron (# 5) 12. Which of the following statements concerning the physical states of the elements at room temperature (25 o C) and pressure is incorrect? a. only two elements, bromine and mercury, are liquids b. the vast majority of the elements are solids c. the gaseous state is more common than the liquid state d. about one-half of the elements are gases 13. Which of the following equations is not balanced? a. H 2 O 2 H 2 O + O 2 b. 2KClO 3 2KCl + 3O 2 c. 2SO 2 + O 2 2SO 3 d. N 2 + 3H 2 2NH 3 3

4 14. Which of the following reactions is incorrectly classified? a. Fe + CuSO4 Cu + FeSO4 (single-replacement) b. F2 + 2NaCl Cl2 + 2NaF (combination) c. H2 + Cl2 2HCl (synthesis) d. BaCl2 + H2SO4 BaSO4 + 2HCl (double-replacement) 15. If the ph of a solution has increased from 6.0 to 7.0 a. an acid has been added to the solution. b. the solution has become basic. c. the solution is now neutral. d. the solution is now more acidic. III PROBLEMS For all mathematical problems, show the equations and/or set-ups and use the rules for significant figures. 16. (12 pts) Ricki placed a weighed sample of gray powder in a long glass tube and gently heated it to decompose it. After the reaction was over, g of tin (#50) metal was left in the tube and she collected.710 g of chlorine gas in a collection tube. a. Find the % composition of the gray powder. b. Predict the formula of the compound using your Periodic Chart c. Ricki looks in a reference book and finds that tin and chlorine can combine to actually make two compounds, but the most common is SnCl 2. Is this the compound that Ricki made? (Substantiate your answer with mathematics.) 17. (10 pts) The astronauts of the Apollo 13 mission to the moon were almost lost in space due to the explosion of a valve on their primary oxygen generator. The lives of the astronauts were threatened by increasing concentrations of carbon dioxide in the spacecraft. Gaseous carbon dioxide (CO 2 ) from the air in a spacecraft can be absorbed (reacted with) open canisters that contain solid lithium hydroxide (LiOH). This reaction produces solid lithium carbonate (Li 2 CO 3 ) and water. a. Write a WORD equation representing this reaction (include all appropriate symbols). 4

5 b. Write an equation using FORMULAS and then balance it. c. Based upon the formula for lithium carbonate, what is the charge on the CO 3 part of the compound? *(CO 3 ) is a subunit. d. Assume that an average astronaut breathes 16 times every minute and with each breath he exhales 0.50 g of CO 2. How long would the air remain safe if the spacecraft contained a canister with 48.0 grams of lithium hydroxide that produced 74.0 grams of Li 2 CO 3 and 18.0 g of water? EXTRA CREDIT (5 pts) Describe how you would use Concept Attainment to teach acids and bases. 5

6 NAME KEY Sec 11am 1:30pm PH-218 EXAM II Friday, March 10, 2006 I SHORT ANSWER 1. (2 pts each) Using the periodic chart, identify the element that is described by each statement below a. Sr There are 36 electrons in this element s ion that has a charge of +2. b. Ag There are 47 electrons in the neutral atom. c. F There are 10 electrons in the ion that has a charge of -1. d. Bi In Group VB and Period 6 e. S Its atomic number is 16 f. Po An atom in group VIB that forms a positive ion g. As,Se,Br,Kr A nonmetal in period 4 2. Match the descriptions on the left with the items on the right. Items may be used more than once or not at all. Some blanks may have more than one answer, but only one is needed. (2 pts each). a. B has a ph of 2 A. H 2 O b. A/D neutral B. H 2 SO 4 c. B tastes sour C. KOH d. C feels slippery D. a salt e. C turns red litmus to blue f. C can neutralize HCl 3. (16 pts) Fill in the blanks or answer the questions. a. Assume that elements with atomic numbers greater than 106 will eventually be made. If so, what would be the atomic number of the next nonmetal? 118 b. How many protons are in the atom of the diatomic element in Group V? 7 c. The total number of atoms present in one unit of Ca3(PO4)2 is 13 6

7 d. What is the total number of hydrogen atoms present in Pb(OH) 2 (C 2 H 3 O 2 ) 2? 8 e. What are valance electrons? They are on the outside of an atom and account for the chemical reactivity of atoms. The number of valence electrons in an atom is determined by the Group #. f. In the electron configuration of a chromium (Cr #24) atom, there are 6 valance electrons. g. Draw the electron dot structure for: the sulfur atom symbol and 6 dots = 1 pt the sulfur ion symbol and 8 dots = 1pt; brackets = 1 pt; charge of -2 = 1 pt i. has 69 neutrons. II MULTIPLE CHOICE Place an x across the letter corresponding to the answer for each question (3 pts each). 4. a b c d 10. a b c d 5. a b c d 11. a b c d 6. a b c d 12. a b c d 7. a b c d 13. a b c d 8. a b c d 14. a b c d 9. a b c d 15. a b c d 4. Which statement about an atom is FALSE? a. The nucleus is the center region of an atom. b. Electrons are found outside the nucleus. c. The nucleus accounts for a small portion of the mass of an atom. d. The number of electrons are equal to the number of protons. 5. Elements constituting a period in the periodic table a. have similar chemical properties b. are called metals c. have consecutive atomic numbers d. will always be in the same group 6. Element X is a conductor of heat and electricity. X is also most likely a. dull and brittle c. element # 35 b. element # 10 d. malleable 7

8 7. The atomic weight of an atom with 39 electrons, 50 neutrons and 39 protons would most likely be a c b d Which of the following statements about the noble gases is incorrect? a. All exist in nature as individual atoms rather than molecules b. They are the most unreactive of all gases. c. All have very stable electron arrangements. d. All have 8 valence electrons. 9. According to the law of definite proportions, if a sample of a compound contains 7.00 grams of sulfur and 3.50 grams of oxygen, then another sample of the same compound which contains 14.0 grams of sulfur must contain a g of oxygen b g of oxygen c g of oxygen d g of oxygen 10. Which option will correctly fill in the blank to define the octet rule? Atoms will electrons so each atom involved will have a noble gas configuration. a. share b. lose c. lose or gain d. lose, gain or share 11. Which of the following elements is represented by a diatomic molecule in a chemical equation? a. chlorine (#17) b. beryllium (#4) c. krypton (#36) d. boron (# 5) 12. Which of the following statements concerning the physical states of the elements at room temperature (25 o C) and pressure is incorrect? a. only two elements, bromine and mercury, are liquids b. the vast majority of the elements are solids c. the gaseous state is more common than the liquid state d. about one-half of the elements are gases 13. Which of the following equations is not balanced? a. H 2 O 2 H 2 O + O 2 b. 2KClO 3 2KCl + 3O 2 c. 2SO 2 + O 2 2SO 3 d. N 2 + 3H 2 2NH Which of the following reactions is incorrectly classified? a. Fe + CuSO4 Cu + FeSO4 (single-replacement) b. F2 + 2NaCl Cl2 + 2NaF (combination) c. H2 + Cl2 2HCl (synthesis) 8

9 d. BaCl2 + H2SO4 BaSO4 + 2HCl (double-replacement) 15. If the ph of a solution has increased from 6.0 to 7.0 a. an acid has been added to the solution. b. the solution has become basic. c. the solution is now neutral. d. the solution is now more acidic. III PROBLEMS For all mathematical problems, show the equations and/or set-ups and use the rules for significant figures. 16. (12 pts) Ricki placed a weighed sample of gray powder in a long glass tube and gently heated it to decompose it. After the reaction was over, g of tin (#50) metal was left in the tube and she collected.710 g of chlorine gas in a collection tube. a. Find the % composition of the gray powder. Wt reactants = Wt products so. X = 1.187g tin g Cl = 1.897g powder % Sn = wt Sn/wt powder x 100 = 1.187g/1.897g x 100 = 62.57% % Cl = 0.710g/1.897g x 100% = 37.4% b. Predict the formula of the compound using your Periodic Chart SnCl 4 c. Ricki looks in a reference book and finds that tin and chlorine can combine to actually make two compounds, but the most common is SnCl 2. Is this the compound that Ricki made? (Substantiate your answer with mathematics.) Find the % composition of SnCl 2 and/or SnCl 4 to see if it matches the laboratory %. For SnCl 2 1 atom Sn = 1 x amu = amu 2 atoms Cl = 2 x 35.5 amu = 71.0 amu total = amu % Sn = 118.7amu/1.897amu x 100 = 62.57% } Ricki made SnCl 2 because the % s % Cl = 71.0amu/189.7amu x 100% = 37.4% match 17. (10 pts) The astronauts of the Apollo 13 mission to the moon were almost lost in space due to the explosion of a valve on their primary oxygen generator. The lives of the astronauts were threatened by increasing concentrations of carbon dioxide in the spacecraft. Gaseous carbon dioxide (CO 2 ) from the air in a spacecraft can be absorbed (reacted with) open canisters that contain solid lithium hydroxide (LiOH). This reaction produces solid lithium carbonate (Li 2 CO 3 ) and water. a. Write a WORD equation representing this reaction (include all appropriate symbols). Carbon dioxide (g) + lithium hydroxide (s) lithium carbonate (s) + water (l) b. Write an equation using FORMULAS and then balance it. CO 2(g) + 2 LiOH (s) Li 2 CO 3(s) + H 2 O (l) 9

10 c. Based upon the formula for lithium carbonate, what is the charge on the CO 3 part of the compound? *(CO 3 ) is a subunit. We know that the CO 3 subunit is paired with 2 Li ions. The charge on each Li is +1. Since the compound must have a net charge of 0, CO 3 must have a charge of -2 to balance the +2 from the Li s. d. Assume that an average astronaut breathes 16 times every minute and with each breath he exhales 0.50 g of CO 2. How long would the air remain safe if the spacecraft contained a canister with 48.0 grams of lithium hydroxide that produced 74.0 grams of Li 2 CO 3 and 18.0 g of water? According to the Law of Conservation of Mass, the total wt of the reactants must be equal to the total wt of the products. Therefore find the #g of CO 2 that would react with the lithium hydroxide; once this has reacted, the next breath of CO 2 would not be absorbed and begin to build up in the spacecraft. CO 2(g) + 2 LiOH (s) Li 2 CO 3(s) + H 2 O (l) (x) + (48.0g) = (74.0g) + (18.0g) So x = 44.0g CO g CO 2 x 1 breath x 1 minute = 5.5 minutes 0.50g CO 2 16 breaths EXTRA CREDIT (5 pts) Describe how you would use Concept Attainment to teach acids and bases. 10

Name Sec: 11am 1:30pm PH-218 Exam II Sample Exam. PART I: Short Answer. 1. (6 pts) Complete the following statements or answer the question.

PART I: Short Answer Name Sec: 11am 1:30pm PH-218 Exam II Sample Exam 1. (6 pts) Complete the following statements or answer the question. a. In the formula CaH 2 (NH 3 ) 2 (SO 4 ) 2 there are total atoms.