Mr. Christopher Salnave CHEMISTRY 1110 Exam IIA Fall ‘12 NAME:_____________________________________ SJU I.D.: (PLEASE PRINT) (eight digit number of front of SJU ID card) INSTRUCTIONS 1. Before starting, print your name and your STJ ID number on this paper and on side one of the

Scantron. 2. You should have nothing at your seat except a #2 pencil, a calculator, and your St. John’s ID.

Everything else should be under the desk. 3. Turn off all electronic devices and place these items under the desk. 4. This exam consists of 25 multiple choice questions + 3 Worked Problems. Indicate the most

appropriate answer to each question on the attached scoring sheet using a #2 pencil and on the exam booklet. The exam and answer sheet must be returned at the end of the exam period.

PROPER CONDUCT DURING AN EXAM 1. Communication between students, by any means, is prohibited. 2. Possession of any unauthorized materials (crib notes, cell phones, mp3 players/recorders, paging

devices, blackberry, laptop, palm pilot, etc.) is prohibited. 3. Violation of either of the above rules can result in a minimum penalty of a grade of zero on this exam.

CONSTANTS and CONVERSION FACTORS

NA = 6.022 × 1023 things/mol c = 2.9979 × 108 m/s 1L.atm = 101 J 1 J = 1 kg·m2/s2 1 cal = 4.184 J 1 atm = 14.696 psi

2

2

smkgJ1 ⋅

= 221 mvKE =

MMg

massmolar gramsMoles == Molarity =

solution of literssolute of moles

∆E = q + w w = ∆P∆V ∆E = Efinal – Einitial ∆Ho = ∆Eo + P∆V q = C · ∆T C = s·m q = s · m · ∆T TK = TC + 273

moles = M × L

C1V1 = C2V2

MiVi = MfVf Formal Charge (FC) = Valence electrons – [bonds – nonbonding e-]

ΔHlattice ≈ q1q2/r

1.) In a chemical reaction one of the reactants is MnO2. It is transformed into MnSO4. What is the change in the oxidation number of the manganese? a. There is no change in oxidation number. b. increase by one unit c. increase by two units d. decrease by one unit e. decrease by two units 2.) The ClO2 molecule was involved in a chemical reaction in which it underwent oxidation.

Based on the change in oxidation numbers, which of the species listed below is a possible product of the reaction?

a. ClO- b. Cl- c. ClO2

- d. Cl2 e. ClO3

- 3.) Balance the half-reaction, H2S → S8, taking place in acidic media. How many electrons are needed to balance the half reaction? a. 12 electrons, left side b. 16 electrons, right side c. 14 electrons, left side d. 6 electrons, right side e. 8 electrons, right side

4.) .) Complete the balancing of the following half-reaction, taking place in basic media, Br-(aq) → BrO3

-(aq) How many hydroxide ions are needed to balance it? a. 2 hydroxide ions, on the left side b. 4 hydroxide ions, on the left side c. 4 hydroxide ions, on the right side d. 6 hydroxide ions, on the left side e. 6 hydroxide ions, on the right side 5.) Complete the balancing of the following half-reaction, taking place in basic media, Br-(aq) → BrO3

-(aq) How many hydroxide ions are needed to balance it? a. 2 electrons, on the left side b. 4 electrons, on the left side c. 4 electrons, on the right side d. 6 electrons, on the left side e. 6 electrons, on the right side 6.) Zinc metal reacts with perchloric acid solution to produce zinc perchlorate (in solution) and hydrogen gas, which escapes. The species being oxidized in this reaction is a. HClO4(aq) b. H2(g) c. Zn2+(aq) d. Zn(s) e. Zn(ClO4)2(aq)

7.) A 350.0 gram sample of copper is initially at 25.0 °C, and it absorbs 12.50 kJ of heat from its surroundings. What is its final temperature?

(specific heat = 0.387 J g-1 °C-1 for copper) a. 38.8 °C b. 67.2 °C c. 92.2 °C d. 117.3 °C e. 156.7 °C 8.) A closed, uninsulated system was fitted with a movable piston. Introduction of 483 J of heat

caused the system to expand, doing 320 J of work in the process against a constant pressure of 101 kPa (kilopascals). What is the value of ΔH for this process?

a.(483 + 320) joules b. (483 - 320) joules c. (320 - 483) joules d. 483 joules e. (-320 - 483) joules

9.) A closed, uninsulated system was fitted with a movable piston. Introduction of 50 J of heat causes the system to expand, doing 100 J of work in the process against a constant pressure of 101 kPa (kilopascals). What is the value of ΔE for this process? a. (100 + 100) joules b. (100 - 50) joules c. (50 - 100) joules d. 100 joules e. (-100 - 50) joules

.

10.) An oil is used in industrial transformers has a density of 1.086 g mL-1 and a specific heat of 1.826 J g-1 °C-1. Calculate the heat capacity of one gallon of this oil.

(1 gallon = 3.785 liters) a. 0.4442 kJ °C-1 b. 0.5239 kJ °C-1 c. 2.251 kJ °C-1 d. 6.364 kJ °C-1 e. 7.506 kJ °C-1

11.) A chemical reaction took place in a 6 liter cylindrical enclosure fitted with a piston (like the cylinder in an internal combustion engine). Over the time required for the reaction to be completed, the volume of the system changed from 0.400 liters to 0.50 liters. Which of the following statements below is true?

a. Work was performed on the system. b. Work was performed by the system. c. The internal energy of the system increased. d. The internal energy of the system decreased. e. The internal energy of the system remained unchanged

12.) When aluminum metal reacts with iron(III) oxide to form aluminum oxide and iron metal, 429.6 kJ of heat are given off for each mole of aluminum metal consumed, under constant pressure and standard conditions. What is the correct value for the standard enthalpy of reaction in the thermochemical equation below?

2 Al(s) + Fe2O3(s) → 2 Fe(s) + Al2O3(s)

a. +429.6 kJ b. -429.6 kJ c. +859.2 kJ d. -859.2 kJ e. -1289 kJ

13.) The thermochemical equation for the reaction between dinitrogen monoxide and oxygen to produce nitrogen dioxide is shown below. Write the thermochemical equation for the reaction when 8.00 mole of nitrogen dioxide is formed.

2 N2O(g) + 3O2(g) → 4NO2(g) ∆Ho = -28.0 kJ

a. N2O(g) + 3O2(g) → NO2(g) ∆Ho = -28.0 kJ b. N2O(g) + O2(g) → NO2(g) ∆Ho = -28.0 kJ c. 4 N2O(g) + 6O2(g) → 8NO2(g) ∆Ho = -56.0 kJ d. ½ N2O(g) + ¾ O2(g) → NO2(g) ∆Ho = -7.00 kJ e. N2O(g) + O2(g) → 2NO2(g) ∆Ho = -14.0 kJ

14.) A 113.25 gram sample of gold is initially at 100.0 °C. It loses 20.00 J of heat to its surroundings. What is its final temperature? (specific heat of gold = 0.129 J g-1 °C-1)

a. 98.6 °C b. -98.6 °C c. 94.6 °C d. -94.6 °C e .96.6 °C 15.) Consider the following thermochemical equation: 2NO(g) + O2(g) → 2 NO2(g) ∆Ho = -113.2 kJ Calculate ∆Ho for the reaction below: 4 NO2(g) → 4NO(g) + 2O2(g) ∆Ho = ?? a. +334.5 kJ b. -146.19 kJ c. +226.4 kJ d. -509.2 kJ e. +192.38 kJ

16.) Which of the following are expected to be diamagnetic in their ground state electron

configurations: S, Xe, Hg, P, Br?

a. S, Xe, and Br b. Hg, Xe, and Br c. Hg and Xe d. S, P, and Br e. All are diamagnetic. 17.) How many pairs of electrons are present in the 3d subshell in the ground state electron configuration of the Cu atom? a. 0 b. 1 c. 3 d. 5 e. 7 18.) The values of n for the valence shells of Sb, Ca, I, and Po are a. 3, 4, 5, 6

b. 5, 5, 6, 6 c. 3, 4, 3, 6 d.5, 6, 5, 4

e.5, 4, 5, 6 19.) A correct description for the electron configuration of a vanadium atom is

a. [Ar] 4s1 3d4, paramagnetic. b. [Ar] 4s2 3d3, paramagnetic. c. [Ar] 4s3 3d2, paramagnetic. d. [Ar] 3d5, paramagnetic. e. [Ar] 4s2 3d3, diamagnetic

20.) Which atom has the smallest first ionization energy? a. Rb b. Na c. Al d. Ne e. O

22.) The formal charge on the nitrogen atom in the nitrate ion is a. 3- b. 0 c. 1+ d. 3+ e. 5+

23.) Based on electronegativity considerations, which species should be the strongest oxidizing agent?

a. O2 b. F2 c. N2 d. Cl2 e. S

21.) Which metal ion is expected to have the electron configuration, [Kr]4d4? a. Mn2+ b. Ru2+ c. Zr2+ d. Mo2+ e. Sr2+

24.) Draw a Lewis structure for CH3NO2. Based on the Lewis structure, what is the formal

charge on the nitrogen and oxygen atoms, respectively? a. 3-, +2, +1 b. 1+, -1, 0 c. 3+, -2, -1 d. 1-, -2, +1 e. 0, -2, +1

25.) Based on the "best" Lewis structure after applying formal charge considerations, how many non-bonding valence electrons are around the nitrogen atom in the nitrite ion?

a. 0 b. 2 c. 4 d. 6 e. 8

26.) (10 points) A volume of 500.0 mL of 0.220 M HCl(aq) was added to a high quality constant-pressure calorimeter containing 500.0 mL of 0.200 M NaOH(aq). The NaOH solution has a density of have a density of 1.15 g mL-1 and the Hydrochloric acid solution has a density of 1.06 g mL-1 . The solution has a specific heat of 4.184 J g-1 o C-1. Ignore the heat capacity of the calorimeter. The temperature of the system rose from 21.60 °C to 26.70 °C. Calculate the heat of reaction in kJ per mole of NaOH (aq) and in kJ per g NaOH.

Please balance the equation using the ion electron method using a basic solution.

27.) Cl2(g) + S2O3

2-(aq) → SO42-(aq) + Cl-(aq)

28.) Draw Lewis dot structures for the following molecules.

a.) SF4

b.) I3 –

c.) SCN-