Exam 1 Chemistry 112 October 7, Part I- Multiple Choice (3 points each). Please choose the single correct answer.

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1 Name Exam 1 Chemistry 112 October 7, 2013 Part I- Multiple Choice (3 points each). Please choose the single correct answer. 1. How many kilometers are there in one meter? a) b) 0.01 c) 100 d) An experiment was performed to find the number of moles of hydrochloric acid in a sample with the following results: Trial Moles The actual number of moles was later determined to be The above results are: a) both accurate and precise b) accurate but imprecise c) precise but inaccurate d) both inaccurate and imprecise 3. What is the electronic configuration of carbon? a) 1s 2 b) 1s 2 1p 4 c) 1s 2 2s 2 d) 1s 2 2s 2 2p 2 4. The compound octanoic acid has a melting point of 16.5 C. In what state will it be at room temperature (25 C)? a) solid b) liquid c) gas d) solution 5. Which of the following has the lowest energy? a) X rays b) red light c) radiowaves d) UV light 6. Which of the following sets of elements has similar chemical properties? a) Cu, Ag, Au b) Ru, Rh, Pd c) ) Li, Be, B d) H, K, Cs 7. What type of bond would be most likely to form between Mg and F? a) nonpolar covalent b) polar covalent c) ionic d) metallic 8. Which of the following represents the correct formula of the compound formed by aluminum (Al) and oxygen (O)? a) AlO b) Al 2 O 3 c) Al 2 O 6 d) Al 6 O 3 9. Which of the following is most likely to lose electrons to form an ionic compound? a) Sn b) C c) H d) S 10. The concentration of H + in a container of brick cleaner is 4.3 x 10-2 M. What is the ph of the brick cleaner? a) 4.3 b) 2 c) -1.4 d) 1.4

2 11. One Canada Mint contains 2.6 x 10-4 moles of oil of wintergreen. How many molecules is this? a) 6.02 x b) 4.3 x c) 1.6 x d) 2.3 x If 6 grams of hydrogen gas reacts with 6 grams of nitrogen gas (3 H N 2 à 2 NH 3 ), which is the limiting reagent? a) H 2 b) N 2 c) NH 3 d) none 13. For the system shown on the right, what is true about the relative strengths of the intermolecular forces in the orange molecules vs. the blue molecules? a) Orange > Blue b) Orange < Blue c) Orange = Blue d) no conclusion possible 14. Buffers keep the solution ph constant through a) oxidation reactions b) reduction reactions c) neutralization reactions d) metathesis reactions 15. What was added to the mixture on the left (below) to achieve the mixture on the right? a) an acid b) a base c) an oxidizing agent d) an emulsifying agent Part II- Short Answer. 1. (10 pts) Circle all the chemical changes below. Iron rusting Release of bubbles from an opened can of soda Mixing ethanol with water. A kettle boiling An acid-base indicator going from colorless to pink 2

3 2. (12 pts) For each of the following compounds, a) Circle the correct type of bonding. b) Predict whether the compound dissolves significantly in water. (Necessary electronegativity values are as follows: O = 3.5; H = 2.1; Ca = 1.0; Cl= 3.0) a) Type of bonding? b) Dissolves in water? CaCl 2 ionic polar covalent nonpolar covalent Yes No OCl 2 ionic polar covalent nonpolar covalent Yes No H 2 ionic polar covalent nonpolar covalent Yes No 3. (9 pts) Draw the Lewis dot structure for each compound in the boxes provided. a) CaCl 2 b) OCl 2 c) H 2 Ca 2+ :Cl: - :Cl: - Cl O Cl: H : H 4. (6 pts) Rank CaCl 2, OCl 2, and H 2 in terms of expected boiling point. H 2 OCl 2 CaCl 2 lowest intermediate highest 5. (3 pts) What type of intermolecular forces are present in a sample of OCl 2? (circle one) dipole-dipole hydrogen bonds London forces 6. (10 pts) Fill in the following table, assuming each column represents a neutral atom: Symbol C-14 O-16 C-12 # Protons # Neutrons # Electrons Mass Number (3 pts) Which two atoms in Question 6 represent a pair of isotopes? C-14 and C-12 3

4 8. (12 pts) Circle any of the following that involve oxidation-reduction. flame tests car battery Al + Cu 2+ à Al 3+ + Cu litmus paper CH O 2 à CO H 2 O HCl + NaOH à NaCl 9. (9 pts) Predict the chemical formulas of the compounds formed by the following pairs of ions or elements: a) Cu + and O Cu 2 O b) Na and N Na 3 N c) Ca and F CaF 2 Part III- Problems. You must clearly show your work for full credit. 1. (7 pts) The most common isotopes of copper are Cu-63 and Cu-65. a) From the periodic table, which one is more abundant? (Circle one.) Cu-63 Cu-65 b) Calculate the expected percentages of each in a sample of naturally occurring copper. x + y =1; x = 1-y where x is the fraction of Cu-63 and y is fraction of Cu x + 65 y = is the average atomic mass from the periodic table 63 (1-y) + 65 y = solving for y: y = 27.5%, so x = 72.5% 2. (10 pts) Glucose (C 6 H 12 O 6 ) reacts with O 2 in the body to release energy. The products are CO 2 and H 2 O. a) Write a balanced equation for this reaction. C 6 H 12 O O 2 à 6 H 2 O + 6 CO 2 b) How many moles of CO 2 are released if 5.0 moles of glucose undergo this reaction? 5.0 moles glucose x 5 moles CO 2 /1mole glucose = 30 moles CO 2 3. (22 pts) Methamphetamine exists in two possible chemical forms, as shown here. 4

5 H N H N H + Cl - A B a) One of these forms is an oily, water-insoluble liquid, whereas the other form is a crystalline salt. Which one is the salt? (circle one) A B b) Jesse is trying to convert form A into form B, but he forgot what Mr. White told him to do. Which of the following can Jesse add to A to get B? (circle one) NaOH HCl O 2 methylamine c) Jesse needs to calculate the moles of A in order to complete the above reaction. What is the chemical formula of A? C 10 H 15 N d) What is the molar mass of A? 10 x 12 g/mol + 15 x 1 g/mol + 1 x 14 g/mol = 149 g/mol e) If Jesse has 75.4 grams of A, how many moles of A does he have, with the correct number of significant figures? (If you didn t get a molar mass for A, then use and do this calculation anyway for full credit.) 75.4 g x 1 mole/149 g = g (3 sig figs) 5

CHM 130: Final Exam Practice Problems

CHM 130: Final Exam Practice Problems 1. Complete the following table: Isotope Mass number # of protons # of neutrons # of electrons strontium-90 neon-19 iron-55 2. Consider Figures A-F below: A B C D