Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 1
Exam 2 Form A
Spring 2004
1) Name ____________________________________
You are to keep this copy of the test. Your name is in case you leave it behind.
2) Use only a #2 pencil on the answer sheet.
3) Before starting the exam fill in your student ID# (not your SS#). Also fill in your name, course number and sign the
form.
4) Fill in the test form section (A, B, C or D). Which form you have is shown in the upper right corner.
5) Do not begin the exam until you are told to.
6) You will not get your scan sheet back!!! Circle your answers on this exam sheet and then transfer them to the scan
sheet when you are satisfied with all your answers. An answer key will be posted on the class web site and in the
glass case across from the lab after the exam.
7) If atomic weights are needed use only those from the attached periodic table.
8) No scratch paper is to be used. Use the back of this exam sheet if necessary.
9) There are 40 equally weighted questions on this exam. You have 90 minutes to complete them.
10) If you believe there is more than one correct answer pick only the best answer.
Useful Data
Constants
c = 2.998 x 108 m/s
h = 6.63 x 10-34 Js
density of H2 O = 1.00 g/mL
NA(Avogadro’s #) =6.022 x 102 3 particles•mol-1
R (gas constant) = 0.08206 L•atm•mol-1•K-1
Units
2.54 cm = 1 inch
3.78 L = 1 gal
1 kg = 2.20 lb
1 % = 10,000 ppm
1 hr = 60 min
1 min = 60 seconds
1 amu = 1.660540 x 10-27 kg
molarity (M) = moles solute/L sol’n
molality (m)= moles solute/ kg solvent
Equations
% = fraction • 100 %
ppm = fraction • 106 ppm
T (in Kelvin) = 273.15 + T (in ˚C)
T (in Celsius) = (5/9) (T (in F) -32)
π = iMRT
∆Tb = imKb
∆Tf = imKf
actual yield (g)
% yield =100% # theoretical yield (g)
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 2
Exam 2 Form A
Spring 2004
1. The elements that make up earth and the rest of the universe are
a. in roughly the same proportions.
b. in drastically different proportions: most of the universe is composed of heavy, radioactive elements that
account for cosmic radiation
c. drastically different: the elements on earth are unique and are found nowhere else in the universe.
d.drastically different: the top ten elements on earth, that make up 99% of the earth are relatively heavy, while
hydrogen and helium make up 99% of the elements in the universe.
e. none of the above
2. The following substances are found as part of the Earth. Given their densities in the liquid state ( units g/mL) which
one do you expect to be more prevalent near the Earth’s surface than the others? All have similar melting points.
material
Al2 S3
Si
NiSO4
density
2.02
2.34
3.68
material
Al2 SO3
AlPO3
density
2.32
2.57
a. Al2 SO3
b. Si
c. NiSO4
d. Al2 S3
e. AlPO3
3. What is the correct name for FeCl3?
a. iron(II) chloride
b. iron trichloride
c. ferrum trichloride
d. ferric trichloride
e. iron(III) chloride
4. Co(ClO4)3 is
a. cobalt trichlorotetroxide.
b. cobalt chlorate.
c. cobalt triperchlorate.
d. cobalt(II) perchlorate.
e. cobalt(III) perchlorate
5. In order, the correct names for the following binary compounds, NO3 , N2 O5 , NO, N4 O are:
a. nitrogen trioxide, dinitrogen pentaoxide, nitrogen monoxide, tetranitrogen monoxide
b. nitrogen trioxide, nitrogen pentaoxide, nitrogen monoxide, tetranitrogen oxide
c. nitrogen trioxide, dinitrogen pentaoxide, nitrous monoxide, tetranitrogen monoxide
d. trinitrogen oxide, dinitrogen pentaoxide, nitrogen monoxide, tetranitrogen oxide
e. trinitronen oxide, dinitrogen pentaoxide, nitrous monoxide, tetranitrogen monoxide
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 3
Exam 2 Form A
Spring 2004
6. HBr is
a. bromic acid
b. hydrogen bromic acid
c. hydrobromic acid
d. perbromic acid
e. bromochloric acid
7. If you have 2.00 moles of roses, it means that you have _______ roses?
a. 2.00 x (6.022 x 102 3)
b. 2.00 x (6.022 x 10-23)
c. 2 / (6.022 x 102 3)
d. 2.00 dozen
e. 5492
8. What is the molar mass of NaCr2 O7 ?
a. 126.982 g/mol
b. 187.979 g /mol
c. 126.98 g/mol
d. 238.98 g/mol
e. 238.9750 g/mol
9. 5.0g of HCN contains ____ moles of the molecule.
a. 0.190 moles
b. 0.19 moles
c. 5.41 moles
d. 5.4 moles
e. 0.384 moles
10. Which one contains the most moles of oxygen atoms?
a. 2 moles of Al2 O3
b. 3 moles of SO2
c. 1 mole of NaIO4
d. 4 moles of NO
e. 2 moles of H2 SO4
11. Choose the answer that has the correct coefficients in the correct order to balance the following chemical equation:
_CaH2 (s) + _ H2 O(l) –> _Ca(OH)2 (s) +_ H2 (g)
a. 1, 1, 1, 1
b. 1, 2, 2, 1
c. 1, 2, 1, 2
d. 2, 4, 2, 4
e. 2, 1, 2, 1,
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 4
Exam 2 Form A
Spring 2004
12. Choose the answer that has the correct coefficients in the correct order to balance the following chemical equation:
_P4 O1 0 + _H2 O –> _H3 PO4
a. 1, 6, 4
b. 2, 12, 8
c. 1, 3, 2
d. 3, 20, 12
e. none of the above
13. An empirical formula and a molecular formula
a. are always the same.
b. are the same when the mass of the empirical formula is equal to the molecular mass.
c. are the same when the mass percentages of all of the elements in the two are the same.
d. are never the same.
e. are the same only if the subscripts in the two formulas are multiples of each other.
14. Copper was the first metal to be produced from its ore because it is the easiest to smelt, that is, to refine by heating
in the presence of carbon (hence the early occurrence of the bronze age). The ore was likely malachite,
Cu2 (OH)2 CO3 . What is the mass percentage of copper in malachite?
a. 28.74%
b. 45.20%
c. 57.47%
d. 40.32%
e. 62.27%
15. A compound called Glucose contains 40.0% Carbon, 6.72% Hydrogen, and 53.3% Oxygen by mass. What is the
empirical formula of the compound?
a. C6H6O6
b. C6H12O6
c. C12H24O6
d. C5H12O6
e. C6H14O12
16. The balanced reaction below releases NH2 Cl (a chloramine) which is one of the compounds used to disinfect
drinking water. A slightly different reaction between bleach (NaOCl (aq)) and NH3 can also produce
chloramines, which is why they should not be mixed. If 10.00 g of NH3 reacts with an excess of Cl2 in the
balanced reaction below how many g of NH2 Cl do you expect to get?
Some useful molar masses are:
NH3
17.031 g/mol
Cl2
70.906 g/mol
H2
NH2 Cl
2.0158 g/mol
51.476 g/mol
NH3 + Cl2 –> 2 NH2 Cl + H2
a. 0.03309 g
b. 0.1410 g
c. 10.00 g
d. 60.45 g
e. 30.22 g
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 5
Exam 2 Form A
Spring 2004
17. Consider the balanced chemical equation below.
SO3 + H2 O –> H2 SO3
If you have 10. gram of SO3 and 10. g of H2 O, which one of the compounds listed below is the limiting reagent ?
a. SO3
b. H2 O
c. H2 SO3
d. Both SO3 and H2 O are limiting reagents since they have the same mass.
e. It cannot be determined due to an insufficient data
18. A complete combustion of 2.0 g of CH4 gives _____ of water.
Useful molar masses are:
CH4
16.043 g/mol
H2 O
18.015 g/mol
a. 4.4918 g
b. 6.0 g
c. 4.5 g
d. 1156.01 g
e. 5.999 g
19. Consider the balanced chemical reaction:
K2PtCl4 + 2NH3 -> Pt(NH3)2Cl2 + 2KCl
Assume that 10.0g of the K2PtCl4 and 10.0 g of the NH3 are present before the reaction. After the reaction, 6.99 g
of the Pt(NH3)2Cl2 was recovered. What is the % yield?
a. 103%
b. 100%
c. 99.9%
d. 96.7%
e. 84.9%
20. Consider the following balanced chemical equation:
2KO2(s) + 2H2O(l) -> 2KOH(s) +O2(g) + H2O2(l)
If you have 20. moles of H2O(l), how many moles of H2O2(l) is expected to be produced?
a. 40. moles
b. 10. moles
c. 5.0 moles
d. 18. moles
e. 20. moles
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 6
Exam 2 Form A
Spring 2004
Questions 21-40 are on chapter 5
21. Concentrated sulfuric acid contains 4 grams of water for every 100 grams of solution. The solvent is
Useful molar masses:
H2 SO4
98.077 g/mol
H2 O
18.015 g/mol
a. water
b. H2 SO4 .
c. concentrated.
d. the same as the solution
e. actually a solute for this case.
22. Units such as M, m and ppm are used to express _______.
a. volume
b. mass
c. concentration
d. number of moles
e. solvent
23. A KCl solution contains 5.0 moles of KCl in 200 mL of solution. What is the molarity?
a. 0.025 M
b. 50. M
c. 2.5 x 101 M
d. 40. M
e. 2.5 x 10 2 2
24. How many moles of solute is needed to prepare 500 mL of 2.0M NaOH aqueous solution?
a. 1mol
b. 1.0 mol
c. 250 mol
d. 300 mol
e. 0.004 mol
25. If the molar concentration of sodium sulfate is 0.10 M, what is the concentration of sodium ion?
a. 0.10 M
b. 0.050 M
c. 0.20 M
d. 0.30 M
e. it is the same as sulfate ions.
26. Which solution would create the higher osmotic pressure (compared to pure water)-one prepared from 1.0 g of
NaCl in 10 mL of water or 1.0 g of CsBr in 10 mL of water?
a. They would have the same osmotic pressures.
b. NaCl would give the higher pressure.
c. CsBr would give the higher pressure.
d. It is impossible to tell.
e. none of the above.
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 7
Exam 2 Form A
Spring 2004
27. The concentration unit of molality is symbolized as
a. M
b. ppm
c. mol
d. M
e. m
28.Concentrated ammonium hydroxide (aqueous ammonia) has a density of 0.90 g/mL and is 28.0% by mass
ammonia. Determine the molar concentration of ammonia. The molar mass of ammonia (NH3 ) is 17.031 g/mol.
a.15. M
b. 1.5 M
c. 3.21 x 10-2 M
d. 31.1 M
e. 25.2 M
29. If you dissolve 4.3 g of MgCl2 in 4.0 kg of water, what is the molality?
a. 0.0181 m
b. 1.1 m
c. 0.17 m
d. 0.011 m
e. 0.0113 m
30. If you have 0.750M sulfuric acid (H2 SO4 ), what is the molality of this solution? Use the following information:
density of the sulfuric acid: 1.046 g/ml, molar mass is 98.1 g/mol.
a. 0.771 m
b. 0.750 m
c. 0.7845 m
d. 2.38 m
e. 0.744 m
31. What is 3.0 x 101 ppm in (mg solute)/(kg of solution)?
a. 3.0 x 101 mg/kg
b. 3.0 x 104 mg/kg
c. 3.0 x 10-2 mg/kg
d. 3.0 x 107 mg /kg
e. 3.0 x 105 mg/kg
32. Electrolytes are ______
a. solutions that exhibit electrical conduction.
b. solutes that exhibit electrical conduction when dissolved in water.
c. Vitamin C.
d. sugar, salt, and deionized water
e. solution that contains deionized water.
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 8
Exam 2 Form A
Spring 2004
33. If you drink 10 gallons of deionized water in a short peroid time (let’s say 5 minutes), what will happen to the
body?
a. Your kidneys work hard removing water and maintain the electrolyte concentration in your blood.
b. Frequent bathroom visits are imminent.
c. Your kidneys may not be able to remove the water from your body fast enough, leading to cells collapsing
from loss of water and possibly a coma.
d. Your kidneys may not be able to remove the water from your body fast enough, leading to cells expanding
and rupturing and possibly a coma.
e. Your body becomes liquidfied.
34. Determine the molal concentration of a sugar solution in water that has a freezing point of -2.10 ºC. Kf = 1.86
˚C/m for water.
a. 1.13 m
b. -1.13 m
c. 3.91 m
d. -3.91 m
e. 2.10 m
35. Determination of molar mass of an unknown sample by an osmotic pressure measurement assumes
a. the unknown in the solution is pure.
b. the unknown is a non-electrolyte.
c. the molecules of the unknown do not pass through the semi-permeable membrane.
d. all of the above.
e. none of the above.
36. What is the osmotic pressure of a solution that is 0.504 M in NaCl versus pure water at 22 ˚C. R= 0.08206
L•atm•M-1•K-1.
a. 0.910 atm
b. 24.4 atm
c. 181. atm
d. 12.2 atm
e. 48.0 atm
37. Which of the following is a colloid?
a. muddy water
b. mineral water
c. Kool-Aid mixed in water
d. ammonia water
e. white grape juice
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 9
Exam 2 Form A
Spring 2004
38. Hydroxyapatite, Ca5 (PO4 )3 (OH), the major component of tooth enamel, is attacked and decomposed by acids more
readily than fluorapatite, Ca5 (PO4 )3 F. Which of the following reactions would be a good comparison for the
reaction of hydroxyapatite with an acid?
a. Ca(s) + 2HCl(aq) ––> CaCl2 (s) + 2 H+
b. CaF2 (s) + 2H+(aq) ––> Ca2+(aq) + 2HF(aq)
c. Ca(OH)2 (s) + 2H+(aq) ––> Ca2+(aq) + 2H2 O(l)
d. Ca(s) + 2H+(aq) ––> Ca2+(aq) + H2 (g)
e. Ca(OH)2 + 2OH-(aq) ––> Ca2+(s) + 2H2 O(l) + O2 (g)
39. Magnesium hydroxide is usually classified as insoluble and magnesium chloride is classified as soluble. Which of
the following equations is a proper NET IONIC equation for the reaction between sodium hydroxide (NaOH) and
magnesium chloride?
a. MgCl2 (aq) + 2NaOH(aq) ––> Mg(OH)2 (s) + 2NaCl(aq)
b. MgCl2 (aq) + NaOH(aq) ––> MgOH(s) + NaCl2 (aq)
c. MgCl2 (aq) + 2NaOH(aq) ––> Mg(OH)2 (s) + 2 Na+(aq) + 2 Cl- (aq)
d. Mg2+ + 2 OH- ––> Mg(OH)2 (s)
e. Mg2+ + 2 Cl- (aq) + 2 Na+(aq) + 2 OH-(aq) ––> Mg(OH)2 (s) + 2 NaCl(aq)
40. The simple acid HCl and the simple base KOH are reacted in water. If the same number of moles of KOH and HCl
were initially in the solution what is in the solution after the reaction is complete? Ignore residual dissociation of
water.
a. HCl(aq), KOH(aq), H2 O, KCl(s)
b. KOH(aq), H2 O, KCl(s)
c. H2 O, KCl(aq)
d. HCl(aq), H2 O, KCl(aq)
e. HCl(aq), KOH(aq), H2 O