Chem 10113, Exam 1
September 23, 2015
Name:
(Please Print)
1.
Write the complete symbol of the specific atom or ion that has 42 electrons, 58 neutrons,
and a mass number of 103.
2.
Complete the following statements for the substance C2B10H12. This substance has a
molar mass of ______________ g/mole and is ______________ % boron by mass. The empirical
formula of this substance is _____________________. (Work need not be shown!)
3.
(10 points)
4.
(12 points)
(3 points)
(7 points)
SHOW ALL WORK. The density of a solution of NaCl in water is 1.16 g/mL. The
solution is 20.0 % NaCl (by mass). Determine the molarity of the solution.
(molar masses: NaCl = 58.4, H2O = 18.0)
SHOW ALL WORK. In a Gen Chem lab experiment, a student carefully mixed 50.0
mL of 0.800 M Ba(OH)2 with 10.0 mL of 2.50 M H3PO4 and observed the formation of a
precipitate (expected to be barium phosphate). After isolation and drying, the pure solid product
weighed 7.10 g. Determine the percentage yield of the reaction. Start by writing a complete,
balanced chemical equation for the reaction that occurs.
{molar masses: Ba(OH)2 = 171, H3PO4 = 98, Ba3(PO4)2 = 602}
SHOW ALL WORK. Having studied the metric prefixes, you'll understand that an
attoliter (aL) is an extremely small volume. Determine the number of sulfate ions in 5.00 aL of a
dilute solution that is 1.50 x 10-5 M Fe2(SO4)3.
5.
(8 points)
6.
(7 points)
Classify each of the following organic compounds according to its family (i.e., alkane,
alcohol, ketone, etc.).
CH3CH2CH2OCH3
(CH3CH2)2NCH3
H2C
CH2
CH
O
C
H2C
CH2
O
H
7.
(5 points)
8.
(5 points)
9.
C
H
CH2
C
OH
CH3
CH2CH3
CH3C
CCH2CH3
Balance the following chemical equations.
(a) _____ GeO2 + _____ NH3 → _____ Ge3N4 + _____ H2O
(b) _____ NH3 + _____ O2 → _____ N2O5 + _____ H2
Circle any of the following that are molecular compounds.
BrF3
Sn(S2O3)2
HIO2
SeCl4
XeO3
NH4NO3
Li2O2
SnS2
SHOW ALL WORK. An unknown compound of molecular mass 249 contains only
phosphorus, nitrogen, and fluorine. Analysis shows that the compound contains 1.226 times as
much fluorine as phosphorus by mass. Determine the molecular formula of the compound.
(8 points)
10. (10 points) SHOW ALL WORK. A mixture of CH4 and C3H8 has a mass of 20 g. It is burned
completely in excess O2 to form a mixture of CO2 and H2O. The product mixture contains 1.6
times as many moles of H2O as of CO2. Determine the mass of CH4 in the original mixture.
(Hint: Write the two combustion reactions and think moles as well as grams!
(molar masses: CH4 = 16, C3H8 = 44, CO2 = 44, H2O = 18)
11. (18 points) Write the chemical formula for each of the following compounds.
Name
Formula
aluminum acetate
calcium azide
hypochlorous acid
cobalt(II) phosphate octahydrate
ammonium oxalate
hydroiodic acid
potassium hydrogen tellurate
rubidium peroxide
tetraphosphorus heptasulfide
12. Write a complete, balanced chemical equation for each of the following processes.
(a) (3 points) The addition of perchloric acid to water.
(b) (4 points) The preparation of magnesium cyanate by a neutralization reaction.