Name _____________________________
UIN ___________________
CHEM 107 Altemose
Mock Exam 1
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EXAM HAS OFFICIALLY BEGUN
1. The formation of a kidney stone can be modeled by mixing aqueous solutions of sodium phosphate,
Na3PO4, and calcium nitrate, Ca(NO3)2, in a basic (i.e, pH > 7) solution. Suppose 250.0 mL of a
0.220 M Na3PO4 (aq) solution is mixed with 150.0 mL of 0.300 M Ca(NO3)2 (aq). What is the final
concentration of the phosphate ion, PO43-, after any reaction that occurs goes to completion?
A. 0.0625 M PO43- - Correct
B. 0.0550 M PO43C. 0.0300 M PO43D. 0.0000 M PO43-
2. What is the precipitate of the reaction below?
LiCl (aq) + Mg(NO3)2 (aq) → ?
A. MgCl2
B. ClNO3
C. LiNO3
D. There is no precipitate - Correct
3. Gallium (atomic weight 69.723 amu) is number 31 in the periodic table and has two naturally
occurring isotopes, 69Ga and 71Ga. Based on the table below, what is the mass (in amu) of 69Ga?
Isotope
69
Ga
71
Ga
Mass (amu)
70.9246
Percent Abundance
60.11%
39.89%
A. 68.9256 amu - Correct
B. 68.7434 amu
C. 69.1287 amu
D. 69. 2539 amu
4. If you add 32.0 mL of a 3.75 M CaBr2 solution to a volumetric flask and then fill the flask to the
100.0 mL line with water, what will the concentration of the bromide ions ([Br–]) in the diluted
solution be?
A. 0.600 M Br–
B. 1.20 M Br–
C. 2.40 M Br– - Correct
D. 3.60 M Br–
5. Which of the images below might represent pure NH3?
A.
B. Correct
C.
D.
6. A square piece of aluminum foil with length and width equal to 5.00 cm weighs 0.154 grams.
Use the density of aluminum (2.70 g/cm3) to find the thickness of the foil. If the diameter of an
aluminum atom is 286 pm, how many aluminum atoms thick is the foil? (1 pm = 10-12 m).
A. 268 atoms
B. 7.98 × 104 atoms - Correct
C. 6.21 × 105 atoms
D. 2.45 × 107 atoms
7. Silver nitrate (MM: 169.872 g/mol) and aluminum chloride (MM: 133.34 g/mol) react with each
other according to the following balanced equation.
3 AgNO3 (aq) + AlCl3 (aq) → 3 AgCl(s) + Al(NO3 )3 (aq)
What mass in grams of AgCl (MM: 143.32 g/mol) is produced when 4.22 g of AgNO3 reacts with
7.73 g of AlCl3?
A. 24.9 g AgCl
B. 17.6 g AgCl
C. 8.31 g AgCl
D. 3.56 g AgCl - Correct
8. Butyl acetate is a compound containing C, H, and O found in many fruits. The synthetic form is
used to impart fruity flavors to candy, ice cream, and other sweets. It is found to be 62.1% carbon
and 10.3% hydrogen, with oxygen making up the remainder. Determine the molecular formula
of butyl acetate given that its molar mass is about 116 g/mol.
A. C3H6O
B. C4H8O
C. C6H12O2 - Correct
D. C8H16O2
9. How many mL of 0.225 M HCl is needed to titrate 30.0 mL of 0.475 M Ba(OH)2 to the
equivalence point? (2 mol HCl : 1 mol Ba(OH)2)
A. 30.0 mL HCl
B. 31.7 mL HCl
C. 63.3 mL HCl
D. 127 mL HCl - Correct
10. Using the balanced chemical equation below, what is the actual yield (in grams) of O2 (MM:
32.00 g/mol) when 27.4 g KClO3 (MM: 122.55 g/mol) decomposes and the percent yield is
81.4%?
2 KClO3 (s) → 2 KCl (s) + 3 O2 (g)
A. 8.74 g O2 - Correct
B. 10.7 g O2
C. 22.3 g O2
D. 33.5 g O2
11. Write the net ionic equation for the reaction below between H3PO4, a weak acid, and KOH, a
strong base. What are the spectator ions in this reaction?
H3PO4(aq) + 3 KOH(aq) → K3PO4(aq) + 3 H2O(l)
A. K+ and PO43B. H+ and OHC. Only K+ - Correct
D. Only PO43-
12. What is the oxidation state (charge) of chromium in Cr2O72-?
A. +2
B. +3
C. +6 - Correct
D. +7
13. Which of the following aqueous solutions has the highest concentration of nitrate ion?
A. 0.1 M Mg(NO3)2
B. 0.2 M Al(NO3)3 - Correct
C. 0.2 M Cu(NO3)2
D. 0.3 M KNO3
14. You need to prepare a 0.0482 M solution of chloride ions, [Cl-] = 0.0482 M, with a total volume
of 375 mL. What mass (in grams) of ZnCl2 (MM: 136.29 g/mol) will you need to prepare this
solution?
A. 1.23 g ZnCl2 - Correct
B. 2.46 g ZnCl2
C. 4.92 g ZnCl2
D. 8.75 g ZnCl2
15. What is the mass of a sample of vanadium (IV) sulfide containing 4.76 × 1023 sulfur atoms?
A. 22.7 grams
B. 32.8 grams
C. 45.5 grams - Correct
D. 90.9 grams
16. Bromine (atomic weight 79.904 amu) is number 35 in the periodic table and has two naturally
occurring isotopes, 79Br and 81Br. What is the percent abundance of 79Br?
Isotope
79
Br
81
Br
A. 90.40%
B. 9.60%
C. 49.33%
D. 50.67% - Correct
Mass (amu)
78.9183
80.9163
Percent Abundance
?
17. Balance the chemical equation for the combustion of citric acid C6H8O7. What is the
stoichiometric coefficient for oxygen gas?
A. 5
B. 7
C. 9 - Correct
D. 11
18. The Haber-Bosch process is the main industrial procedure for producing ammonia today, and is
represented by the reaction below:
N2(g) + 3 H2(g) → 2 NH3(g)
How many grams of ammonia (NH3, MM = 17.03 g/mol) will be produced if 141.1 grams of
hydrogen gas (MM = 2.02 g/mol) are reacted with excess nitrogen gas?
A. 589 grams NH3
B. 342 grams NH3
C. 141 grams NH3
D. 793 grams NH3 - Correct
19. How many neutrons, protons and electrons are there in a 39K+ ion?
A. 20 n, 19 p+, 18 e- - Correct
B. 19 n, 20 p+, 18 eC. 18 n, 19p+, 20 eD. 18 n, 20 p+, 19 e-
20. Consider the image below representing a chemical reaction. In this reaction, which species is
the limiting reactant? B is correct
A. AB3
B. B2
C. A2
D. No limiting reactant, reactant are in stoichiometrically equivalent amounts
________________End of Exam (Each Question Worth 10 pts__________________
Ions, Constants and Conversions
Ions
Ions
Constants and Conversions
acetate
CH3COO‒
hydroxide
OH‒
NA = 6.022 x 1023
ammonium
NH4+
nitrate
NO3‒
1 L = 1000 mL
carbonate
chlorate
cyanide
CO32‒
ClO3‒
CN‒
phosphate
sulfate
PO43‒
SO42‒
Solubility Chart
Ion
Exceptions
Na+, K+
None
NH4+
none
Cl−, Br−, I−
Ag+, Hg22+, Pb2+
usually
F−
Mg2+, Ca2+, Sr2+, Ba2+, Pb2+
soluble
NO3−
none
ClO4−, ClO3−
none
CH3COO−
none
SO42−
Ag+, Hg22+, Pb2+, Ca2+, Sr2+, Ba2+
OH−
Li+, Na+, K+, Rb+, Cs+, NH4+, Ba2+
S2−
Na+, K+, NH4+, Ba2+
CO32−
Na+, K+, NH4+
CrO42−
Na+, K+, NH4+
PO43−
Na+, K+, NH4+
usually
insoluble