CHEM 200/202 Fall 2013
Course (200 or 202): ________
Exam 1
September 20, 2014
Lab Section Number:_____!
Name (printed):_____________________________________________!
!
Signature:______________________________________!
!
This exam consists of 32 questions at 5 points each for a total of 160 points. Make
sure that your test has all of the pages. Please read each problem carefully. There are
no intentionally misleading questions; each problem should be taken at its face value.
Please mark your answers on the Scantron sheet provided to you and on the actual
exam.!
You will be given a periodic table and an exam information sheet to use during the
exam. You may remove it from the exam make it more accessible. You may also use the
designated Casio fx-300ms-plus calculator or equivalent non-programmable nongraphing scientific calculator during the exam. A blank page has been included in the
test as scratch paper. You are not allowed to use any devices capable of accessing the
internet, textbooks, notes, or homemade reference sheets during the exam.!
You may leave if you finish the exam early. Give the exam and the information sheet to
your TA and leave quietly without disturbing other students. Before leaving, check that
all your answers have been properly entered on the Scantron sheet and the exam and
that your name is written on every page of the exam and on the Scantron sheet.!
All cell phones and electronic devices must be turned off and put away. Please remove
all hats and caps. Place your books and all papers out of sight under your seat. If the TA
believes that you might be looking at your neighbor’s paper, you will be asked to move
to a new location.!
Exam scores will be posted on Blackboard as soon as the grading is complete. Your test
will be returned to you in the first lab meeting of next week. If you have any questions
regarding the grading of your exam, please notify your TA.!
The time available for the exam is 120 minutes. Good luck!!
!
1 of 10
CHEM 200/202 Fall 2013
Exam 1
Name: ___________________________________________
!
September 20, 2014
!Lab Section #: _______!
Please mark your answers on the scantron sheet using a #2 pencil and also mark your answers
on the exam itself.!
!
Mark Test From “A” on your scantron.!
!
1. A rough-cast steel amalgam ball-bearing is lost while being transported for final milling. The
ball-bearing has a circumference of 34.4 mm, and weighs 6.17 g. What is the density of the
amalgam in g/cm3? Note: Volume of a sphere = (4/3)×r3×π and Circumference = 2×r×π!
(a) 8.97 g/cm3!
(b) 1.12 g/cm3!
(c) 1.12×10－3 g/cm3!
(d) 9.05 g/cm3!
(e) 2.69 g/cm3
!
2. Which formula listed below is the proper representation of nitrite?!
(a) N3－!
(b) NO2!
(c) NO3－!
(d) NO2－!
(e) NH4+
!
3. Carry out the following calculation, make sure your answer has the correct number of
significant figures:!
(a) 2.5!
(1.50 × 3.432) +13.6
(b) 2.466!
7.6
(c) 2.47!
(d) 2.467!
(e) 2.4
!
4. One amu is defined as:!
(a) The mass of a proton.!
(b) 1/20th the mass of an atom of 20Ne.!
(c) The mass of an atom of 1H.!
(d) 1/12th the mass of an atom of 12C.!
(e) 1/16th the mass of an atom of 16O.
!
5. What the AZX notation for an atom with 82e－, 125n0, and 82p+ and state whether the
identified atom is an atomic isotope, or an atomic ion.!
(a) 8282Kr; isotope!
(b) 82125Un; ion!
(c) 20782Pb; ion!
(d) 82207Pb; isotope!
(e) 20782Pb; isotope
!
2 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
6. Magnesium has three naturally occurring isotopes, 24Mg (isotopic mass = 23.9850 amu,
abundance = 78.99%), 25Mg (isotopic mass = 24.9858 amu, abundance = 10.00%), and
26Mg (isotopic mass = 25.9826 amu, abundance = 11.01%). Calculate the atomic mass of
magnesium.!
(a) 12.00 amu!
(b) 24.98 amu!
(c) 24.30 amu!
(d) 22.99 amu!
(e) 23.78 amu
!
7. Give the number of hydrogen atoms in the formula unit of ammonium hydrogen phosphate
(NH4)2HPO4; and determine the compound’s molar mass:!
(a) 7 H; 132.1 g/mol!
(b) 9 H; 129.0 g/mol!
(c) 6 H; 115.0 g/mol!
(d) 9 H; 132.1 g/mol!
(e) 8 H; 131.0 g/mol
!
8. Calculate the mass in grams of 4.63×1024 Li atoms.!
(a) 53.4 g!
(b) 2.80×1025 g!
(c) 5.34×10－2 kg!
(d) 3.21×1025 g!
(e) 46.3 g
!
9. Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain and water
proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.!
(a) 6.876×1024 Cr atoms!
(b) 3.227×1023 Cr atoms!
(c) 1.065×1023 Cr atoms!
(d) 2.238×1024 Cr atoms!
(e) 0.50 mol Cr atoms
!
10. Household sugar, sucrose, has the molecular formula C12H22O11. What is the % of carbon in
sucrose, by mass?!
(a) 52.8%!
(b) 42.1%!
(c) 33.3%!
(d) 27.6%!
(e) 44.4%
!
11. A compound containing chromium and silicon contains 73.52 mass percent chromium.
Determine it empirical formula.!
(a) CrSi3!
(b) Cr2Si!
(c) Kr3S!
(d) Cr2Si3!
(e) Cr3Si2
!
3 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
12. Balance the following equation: B2O3(s) + HF(l) → BF3(g) + H2O(l)!
(a) B2O3(s) + 2HF(l) → 2BF3(g) + 2H2O(l)!
(b) B2O3(s) + 3HF(l) → 2BF3(g) + 3OH－(aq)!
(c) B2O3(s) + 6HF(l) → 2BF3(g) + 3H2O(l)!
(d) B2O3(s) + 6HF(l) → 2BF3(g) + 6H2O(l)!
(e) B2O3(s) + H6F6(l) → B2F6 + H6O3(l)
!
13. How many molecules of molecular oxygen react with four molecules of NH3 to form four
molecules of nitrogen monoxide and six molecules of water?!
(a) 2!
(b) 5!
(c) 6!
(d) 4!
(e) 10
!
14. Aluminum will react with bromine to form aluminum bromide which is used as an acid
catalyst in organic synthesis. The unbalanced reaction for the formation of aluminum
bromide is shown below. How many moles of Al are needed to form 2.43 mol of Al2Br6?
Al(s) + Br2(l) → Al2Br6(s)!
(a) 6.48 mol!
(b) 131 mol!
(c) 2.43 mol!
(d) 1.22 mol!
(e) 4.86 mol
!
15. Ammonia, an important source of fixed nitrogen that can be metabolized by plants, is
produced using the Haber process in which nitrogen and hydrogen combine. Given an
excess of hydrogen, how many grams of nitrogen are needed to produce 325 grams of
ammonia?
N2(g) + 3H2(g) → 2NH3(g)!
(a) 267 g!
(b) 401 g!
(c) 163 g!
(d) 325 g!
(e) 178 g!
!
16. What is the oxidation number of phosphorus in a molecule of disodium hydrogen phosphate
(Na2HPO4)?!
(a) 0!
(b) -1!
(c) +3!
(d) -3!
(e) +5
!
4 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
17. Which of the elements below always has an oxidation number of +1 when it is not in its
elemental state?!
(a) Hydrogen!
(b) Rubidium!
(c) Aluminum!
(d) Iron!
(e) Fluoride
!
18. Of the reaction types listed below, which is not a type of redox reaction?!
(a) Displacement!
(b) Decomposition!
(c) Neutralization!
(d) Combination!
(e) Combustion
!
19. In which of the nitrogen containing compounds listed below does nitrogen have the highest
(largest, positive) oxidation number?!
(a) NH3!
(b) NH4+!
(c) NO2!
(d) NO2－!
(e) N2O
!
20. Which reaction below depicts the proper, balanced, net ionic equation for the reaction of
barium hydroxide (Ba(OH)2) with sulfuric acid (H2SO4)?!
(a) 2OH－(aq) + 2H+(aq) → 2H2O(l)!
(b) Ba2+(aq) + 2OH－(aq) + 2H+(aq) + SO42－(aq) → BaSO4(s) + 2H2O(l)!
(c) 2BaOH(aq) + H2SO4(aq) → Ba2SO4(s) + 2H2O(l)!
(d) Ba2+(aq) + SO42－(aq) → BaSO4(s)!
(e) Ba(OH)2 (aq) + H2SO4 (aq) → BaSO4(s) + 2H2O(l)
!
21. A solution is prepared by dissolving 14.65 g of barium hydroxide in 55.34 mL of water. This
solution is then titrated with a 2.435 M solution of hydrochloric acid. What volume of titrant
is required to neutralize the barium hydroxide solution?!
(a) 104.1 mL!
(b) 70.24 mL!
(c) 31.56 mL!
(d) 3.00 mL!
(e) 35.12 mL
!
22. Which of the following combination of reagents would result in the formation of a precipitate?
Note: the reagents are not stoichiometrically balanced.!
(a) Pb(NO3)2(aq) + Na2S(aq) →…!
(b) HNO3(aq) + Ca(OH)2(aq) →…!
(c) KClO4(aq) + LiH2PO4(aq) →…!
(d) Ba(NO3)2(aq) + Ca(OH)2(aq) →…!
(e) NH4OH(aq) + H2SO4(aq) →…
!
5 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
23. Which of the chemicals listed below is neither a strong acid nor a strong base?!
(a) Sr(OH)2!
(b) H2SO4!
(c) NaOH!
(d) CH3OH!
(e) HClO4
!
24. For the redox reaction below, identify the reducing agent.
8H+(aq) + Sn(s) + 6Cl－(aq) + 4NO3－(aq) → SnCl62－(aq) + 4NO2(g) + 4H2O(l)
!
(a)
(b)
(c)
(d)
(e)
H+(aq)!
Sn(s)!
Cl－(aq)!
NO3－(aq)!
SnCl62－(aq)
!
25. A balloon contains 5.483 g of an unknown gas. At a temperature of 26.4°C the balloon has
a volume of 3.679 L and a pressure of 1.075 atm. What is the molar mass of the gas?!
(a) 34.1 g/mol!
(b) 3.00 g/mol!
(c) 0.882 g/mol!
(d) 24.0 g/mol!
(e) 44.0 g/mol
!
26. An acetylene gas cylinder used by a welder has a total internal volume of 50.0 L. If the
cylinder contains 37.4 moles of acetylene, what will be the pressure in the cylinder (in torr) if
the cylinder is 25.0°C?!
(a) 18.3 torr!
(b) 0.0241 torr!
(c) 1.17×103 torr!
(d) 1.39×104 torr!
(e) 1.85×103 torr
!
!
27. Which of the substances below will yield the highest pressure when placed in a 3.65 L
cylindrical tank that is kept at 20.4°C?!
(a) 4.98 g of He(g)!
(b) 51.7 g of SO2(g)!
(c) 0.843 mol of CO2(g)!
(d) 15.2 mol of C6H12O6(s)!
(e) 19.7 g of NH3(g)
!
6 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
28. Lithium undergoes a displacement redox reaction when placed in water (see reaction
below). This reaction is carried out and all the hydrogen gas is captured in a 0.65 L tank,
and the pressure and temperature in the tank are found to be 5.86 atm and 37.2°C.
Determine the mass of lithium used in the reaction, there was an excess of water.
2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g)!
(a) 46.4 g!
(b) 1.73 g!
(c) 1.04 g!
(d) 92.8 g!
(e) 2.08 g
!
29. The atmosphere of Neptune is composed of helium, hydrogen, and methane gas. The total
atmospheric pressure has been measured to be 4.05 atm. The partial pressures for gas are
as follows: helium 0.7695 atm, hydrogen 3.24 atm, and methane 0.0405 atm. What is the
percentage (in terms of moles) of helium in Neptune’s atmosphere?!
(a) 80.0%!
(b) 1.00%!
(c) 33.3%!
(d) 19.0%!
(e) 10.5%
!
30. As it pertains to the ideal gasses and the kinetic-molecular theory, which statement about
gasses is FALSE?!
(a) The collisions between gas particles are elastic.!
(b) Gas particles are in constant, random, straight-line, motion.!
(c) The space occupied by the gas particles is negligible in comparison to the volume of
the gas.!
(d) Gasses are behave different based on their chemical identity.!
(e) Gasses will conform to (fill entirely) the vessel that they are place in.
!
!
7 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
The following problems are extra credit. You will not be penalized for wrong answers!
!
31. Small metal cylinders, filled with 16.0 g of compressed CO2(g) are often used by bicyclists to
inflate flat tires. If such a cylinder has a volume of 25.0 mL, and can fill a 1.25 L bicycle
inner tube to a pressure of 7.05 atm at 22.4°C, what is the pressure of CO2(g) inside a
sealed cylinder at the same temperature?!
(a) 0.141 atm!
(b) 7.05 atm!
(c) 141 atm!
(d) 352 atm!
(e) 68.4 atm
!
32. A 5.63 g sample of methane (CH4) is combusted with a stoichiometric amount of oxygen.
The gas produced from the combustion is captured in a 6.48 L canister and is at a
temperature of 126°C. What is the pressure inside the cylinder?
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)!
(a) 3.55 atm!
(b) 1.68 atm!
(c) 5.32 atm!
(d) 28.4 atm!
(e) 1.77 atm
!
Solubility Rules for Ionic Compounds in Water
Soluble Ionic Compounds
Solubility Rules:
Exceptions:
All compounds of Group 1A (1) ions Li+, Na+, K+, etc,
and ammonium ion NH4+ are soluble
All common nitrates (NO3-) are soluble
All common acetates (CH3COO-) are soluble
Most perchlorates (ClO4-) are soluble
All common chlorides (Cl-) are soluble
All common bromides (Br-) are soluble
Ag+, Pb2+, Cu+, Hg22+
All common iodides (I ) are soluble
All common sulfates (SO42-) are soluble
Ca2+, Sr2+, Ba2+, Ag+, Pb2+
Insoluble Ionic Compounds
Insolubility Rules:
Exceptions:
All common metal hydroxides (OH-) are insoluble
Group 1A (1) ions
The larger Group 2A (2) ions beginning with Ca2+
2All common carbonates (CO3 ) are insoluble
Group 1A (1) ions
All common phosphates (PO43-) are insoluble
NH4+ ion
All common sulfides (S-) are insoluble
Group 1A (1) ions
Group 2A (2) ions
NH4+ ion
!
!
8 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
This page left intentionally blank!
!
9 of 10
CHEM 200/202 Fall 2013
Exam 1
September 20, 2014
This page left intentionally blank
10 of 10