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SAMPLE

CHEM 1411

SYSTEM FINAL EXAM

Need Scantron

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CHEM 1411 - FINAL EXAM

PART I Multiple Choice (2 points each)

Please DO NOT write or mark on this paper. Mark your answer on your Scantron.

1. A sample that cannot be separated into two or more substances by physical means is

A) a heterogeneous mixture B) a compound

B) either a compound or an element D) an element

2. The enthalpy of combustion of benzoic acid is -26.4 kJ/g. What is the enthalpy of combustion

expressed in joules per kilogram?

A) -2.64 x 103 J/kg B) -2.64 x 104 J/kg C) -2.64 x 109 J/kg D) -2.64 x 107 J/kg

3. Write the result of the following calculation in scientific notation: 0.0263 cm2 ÷ 88.2 cm

A) 2.98 x 105 cm B) 2.98 x 104 cm C) 2.98 x 10-3 cm D) 2.98 x 10-4 cm

4. The oxidation number of barium in BaO is ____________.

A) +1 B) +4 C)-1/2 D) +2

5. How many moles of a gas are in a gas sample occupying 0.738 L at 135 mmHg and 30oC?

A) 190 mol B) 4.01 mol C) 40.5 mol D) 0.00527 mol

6. The nucleus of a 208Pb nuclide contains

A) 208 neutrons and 290 electrons B) 82 protons and 208 neutrons

B) 208 protons and 126 electrons D) 82 protons and 126 neutrons

7. Which of the following properties, in general, increases from left to right across a period in the

periodic table?

A) ionic charge B) atomic radius C) density D) first ionization energy

8. What is the bond angle in a linear molecule or ion?

A) 120o B) 109o C) 180o D) 72o

9. A bond in which an electron pair is unequally shared by two atoms is

A) polar covalent B) coordinate covalent C) ionic D) nonpolar covalent

10. Which of the following electron configuration is impossible, according to the Pauli exclusion

principle?

A) 1s22s22p6 B) 1s22s22p3 C) 1s22s3 D) 1s22s22p63s1

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11. How many atoms of carbon are there in 0.51 mol of procaine, C13H20N2O2, a “pain killer” used by

dentists?

A) 6.6 x 1023 B) 4.3 x 1024 C) 4.0 x 1024 D) 6.1 x 1023

12. What is the mass in grams of 0.699 mol of glucose, C6H12O6?

A) 0.00388 g B) 67.1 g C) 126 g D) 21.0 g

13. Calculate the number of moles of bromine present in 14.5 mL of Br2(l), whose density is 3.12 g/mL.

A) 3.53 mol B) 0.181 mol C) 0.566 mol D) 0.283 mol

14. An ore sample is found to contain 24.1 g of mercury and 50.7 g of waste rock (gaugue). What is the

percent by mass of mercury in the ore?

A) 32.2 % B) 47.4 % C) 0.322 % D) 0.474 %

15. 2KHCO3(s) → K2CO3(s) + CO2(g) + H2O(l)

Based on the above equation, how many moles of potassium carbonate will be produced if 454 g of

potassium hydrogen carbonate are heated?

A) 2.27 mol B) 3.29 mol C) 11.4 mol D) 227 mol

16. What hybrid orbitals of sulfur are involved in the bonding in sulfur trioxide?

A) sp2 B) sp2d C) sp3 D) sp3d2

17. A π (pi) bond is the result of the ______________________.A) overlap of two s orbitals.

B) overlap of two d orbitals along their axes.

C) sideways overlap of two parallel p orbitals D) overlap of an s orbital and a p orbital

18. Which of the following statements is true concerning the two nuclides 3He and 4He?

A) they have the same number of neutrons B) they are isotopes

C) they have the same relative atomic mass. D) they have the same mass number.

19. If q = -101 KJ for a certain process, that process

A) requires a catalyst B) is exothermic C) occurs rapidly D) is endothermic

20. Which of the following molecules is polar?

A) SF6 B) CCl4 C) BF3 D) NO2

21. Which of the following is an exothermic process?

A) work is done by the system on the surroundings

B) heat energy flows from the system to the surroundings

C) work is done on the system by the surroundings

D) heat energy is absorbed or released by the system

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22. Which of the following aqueous solutions would be expected to be the best conductor of electricity?

A) 0.10 M CH3COOH B) 0.10 M HCl C) 0.10 M Na2SO4 D)10 M NaCl

23. Lithium has two naturally occurring isotopes, 6Li and 7Li. The average atomic mass of lithium is

6.941. Which of the following statements concerning the relative abundance of each isotope is

correct?

A) the abundance of 7Li is greater than 6Li.

B) the abundance of 7Li is less than 6Li.

C) the abundance of 6Li is equal to the abundance of 7Li.

D) not enough data is provided to determine the correct answer.

24. The melting point of nitrogen is 63 K. What is the temperature in degrees Celsius?

A) 63oC B) -336oC C) -63oC D) -210oC

25. Which molecule or ion has a trigonal pyramidal molecular geometry?

A) BF3 B) C2H4 C) SO3 D) SO32-

26. Sodium and potassium have similar chemical and physical properties. This is best explained by the

fact that both elements

A) have the same ground-state valence-electron configuration.

B) have low relative atomic masses

C) are in period 1 of the periodic table.

D) have relatively low first ionization energies.

27. Calculate the mass of gold that occupies the same volume as 62.9 g of cobalt. The density of cobalt is

8.90 g/mL and the density of gold is 19.30 g/mL

A) 2.73 g B) 136 g C) 1.08 x 104 g D) 0.0345 g

28. Which set of ions are isoelectronic in their ground-state electron configuration?

A) N3-, O2-, Mg2+, Al3+ B) Na+, K+, Rb+, Cs+

C) F-, Cl-, Br-, I- D) Mg2+, Ca2+, Sr2+, Ba2+

29. How many electrons does the ion 3517Cl- have?

A) 16 B) 36 C) 18 D) 34

30. In general, atomic radii

A) decrease from left to right in a period and increase down a group.

B) increase from left to right in a period and decrease down a group.

C) do not change across a period or a group.

D) decrease from left to right and decrease down a group.

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31. What is the ground state electron configuration of of 34Se?

A) [Ar]3d104p6 B) [Ar]4s23d104p4

C) [Kr]4s23d104p4 D) [Ar]4s24d104p4

32. What is the molecular geometry around an atom in a molecule or ion which is surrounded by zero

lone pairs of electrons and four single covalent bonds?

A) Tetrahedral B) linear C) bent D) trigonal pyramidal

33. A 22.4 L sample of nitrogen at 3.65 atm and 22oC is simultaneously expanded to 57.4 L and heated to

38oC. What is the new pressure of the gas?

A) 2.46 atm B) 1.50 atm C) 204 atm D) 334 atm

34. Which of the following indicates the existence of strong intermolecular forces of attraction in a

liquid?

A) a very low critical temperature B) a very low boiling point

C) a very low vapor pressure D) a very low viscosity

35. The specific heat capacity of lead is 0.13 J/g.K. How much heat (in Joules) is required to raise the

temperature of 15 g of lead from 22 oC to 37 oC?

A. 29 J B) 0.13 J C) -0.13 J D) 2.0 J

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PARTIAL CREDIT PROBLEMS-SHOW ALL YOUR WORK TO GET FULL

CREDIT. (5pts each)

SELECT ANY SIX QUESTIONS

1. Consider the following reaction:

2Na3PO4(aq) + 3Ba(NO3)2(aq) → Ba3(PO4)2(s) + 6NaNO3(aq)

Suppose a solution containing 3.50 g of Na3PO4 is mixed with a solution containing 6.40 g

Ba(NO3)2. How many grams of Ba3(PO4)2 can be formed?

2. Ethanol, C2H5OH, is made industrially by the reaction of water with ethylene, C2H4. Calculate the

value of ΔHo for the reaction;

C2H4(g) + H2O(l) → C2H5OH(l)

given the following thermochemical equations:

C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(l) ΔHo = -1411.1 kJ

C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) ΔHo = -1367.1 kJ

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3. Ethylene glycol, the substance used in automobile antifreeze, is composed of 38.7% C, 9.7% H,

and 51.6% O by mass. Its molar mass is 62.1 g/mol. Determine both the empirical and molecular

formulae of ethylene glycol.

4. A sample of blood completely fills an 8.20 cm3 vial.

The empty vial has a mass of 10.30 g. The vial has a mass of 18.91 g after being filled with

blood. What is the density of blood?

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5. Balance the following formula equation and then write its net ionic equation.

Pb(NO3)2(aq) + Fe2(SO4)3(aq) → PbSO4(s) + Fe(NO3)3(aq)

6. An important chemical reaction in the manufacture of Portland cement is the high temperature

decomposition of calcium carbonate to give calcium oxide and carbon dioxide.

CaCO3(s) → CO2(g) + CaO(s)

Suppose a 1.25 g sample of CaCO3 is decomposed by heating. How many milliliters of CO2

gas will be evolved if the volume will be measured at 745 torr and 25 oC?

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7. Calculate the amount of energy (in KJ) needed to heat 346 g liquid water from 0oC to 182 oC.

Assume that the specific heat of water is 4.148 J/g.oC over the entire liquid range, that the specific

heat of steam is 1.99 J/g.oC and that the ∆Hvap for water is 40.79 KJ/mol.

8. What is the wavelength (in nanometers) of a photon emitted during a transition from ni = 6 to

nf = 4 state in the H atom?

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MULTIPLE CHOICE ANSWERS

1. C 2. D (-26.4 kJ/g)(1000g/1 kg)(1000J/1 kJ) = -2.60x106 J/kg

3. D (0.0263 cm2)/ 88.2 cm = 2.98x10-4 cm

4. D 5. D n = (PV/RT) = (135)(0.738) / (760)(0.0821)(303) = 0.00527 mol

6. D 7. D 8. C 9. A 10. C

11. C (0.51 mol)( 6.022x1023 molecules/1 mol)( 13 atoms/1 molecule) 4.0x1024 carbon atoms

12. C (0.699 mol)( 180 g/mol) = 126 g

13. D m =D.V = (3.12 g/ml). (14.5 ml) = 45.24 g (45.24 g)(1 mol Br2/160 g) = 0.283 mol

14. A Total sample = 24.1 + 50.7 = 74.8 g %mercury = (24.1 g/74.8 g) x100 = 32.3 %

15. A mol K2CO3 = (454g KHCO3)( 1 mol CO2/2x100 g KHCO3) = (454/200 mol) = 2.27 mol

16. A 17. C 18. B 19. B q < 0 (negative) exothermic

20. D 21. A & B 22. C Na2SO4 has three ions (2Na+ and SO42-)

23. A 6.941 is closer to 7 therefore 7Li isotope has higher percentage.

24. D 25. D 26. A

27. B V = (m/d)cobalt = (m/d)gold (62.9/8.90)cobalt = (m/19.30) gold

m(gold) = (19.30x62.9)/8.90 = 136 g

28. A 29. C 30. A 31. B 32. A

33. B (P1V1/T1) = (P2V2/T2) P2 =(P1V1T2)/ (V2T1) = (3.65)(22.4)(311)/ (57.4)(295) = 1.50 atm 34.

34. C 35. A q = m.s. Δt = 15(0.13)(37-22) = 29 J

PARTIAL CREDIT PROBLEM ANSWERS

1. Grams Ba3(PO4)2 from Na3PO4 = (3.50x601.92)/(2x163.941) = 6.43 g

Grams Ba3(PO4)2 from Ba(NO3)2 = (6.40x601.92)/ (3x261.337) = 4.91g (less product)

2. First reaction + Reverse second reaction = (-1411.1 kJ) + (+1367.1 kJ) = - 44.0 kJ

3. C =(37.7/12) = 3.225 3.225/3.225 = 1 C

H = (9.7/1) =9.7 9.7/3.225 = 3 H

O = (51.6/16) = 3.225 3.225/3.225 = 1O CH3O Empirical formula

(CH3O)n = 62.1 (12+3+16)n = 62.2 (31)n = 62.1 n =2 C2H6O2 Molecular formula

4. m =18.91 -10.30 = 8.61 g bloog d =(m/V) = (8.61 g/8.20 ml) d = 1.05 g/ml

5. Balanced Equation: 3 Pb(NO3)2(aq) + Fe2(SO4)3(aq) → 3 PbSO4(s) + 2 Fe(NO3)3(aq)

Net Ionic Equation: Pb2+ (aq) + SO42- (aq) PbSO4(s)

6. mole CaCO3 = (1.25g)( 1 mol/100g) =1.25x10-2 mol CaCO3

V = (nRT)/P = (1.25x10-2)(0.0821)(298)/ (745/760) = 0.312 L = 311 ml

7. Q1 = m.s. Δ t = (346)(4.184)(100-0) = 145000/1000 = 145 kJ

Q2 = m . ΔHvap = (346g) (1 mol H2O/18 g)(40.79 kJ/mol) = 784 kJ

Q3 = m.s. Δ t = (246)(1.99)(182-100) = 56460 J/1000 = 56.46 kJ

Q = Q1 + Q2 + Q3 = 145 + 784 + 56.46 = 985 kJ

8. ΔE = (-2.18x10-18)(1/nf2 -1/ni

2) = (-2.18x10-18)(1/42 -1/62) = 7.60x10-20 J

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λ = (ΔE)/ hc = (7.60x10-20 J) / (6.63x10-34)(3.00x108) = 2.63x10-6 m x109 2.63x103 nm