Name: _____________________________________
Chemistry 400: General Chemistry
Miller
Exam I September 23, 2015
Approximately 150 points
Please answer each of the following questions to the best of your ability. If you wish to receive partial credit, please show your work.
For multiple choice, there is no partial credit (unless otherwise noted) and there is only one correct answer. For multiple choice,
please clearly mark the correct answer. Good luck!
Definition of ppm and ppb:
1 ppm = 1 x 10-6 g/mL
1 ppb = 1 x 10-9 g/mL
I. Multiple Choice / Fill in the blank (4 points each)
1. What is the concentration of a solution, in parts per million, if 0.02 gram of Na3PO4 is dissolved in 1000 mL of water?
A. 20 ppm
B. 2 ppm
C. 0.2 ppm
D. 0.02 ppm
E. None of these
2. All of the following reactions
2Al(s) + 3Br2(l) → 2AlBr3(s)
2Ag2O(s) → 4Ag(s) + O2(g)
CH4(l) + 2O2(g) → CO2(g) + 2H2O(g)
can be classified as
A. oxidation-reduction reactions
B. combustion reactions
C. precipitation reactions
D. A and B
E. A and C
3. Aqueous solutions of potassium sulfate and ammonium nitrate are mixed together. Which statement is correct?
A. Both KNO3 and NH4SO4 precipitate from solution.
B. A gas is released.
C. NH4SO4 will precipitate from solution.
D. KNO3 will precipitate from solution.
E. No reaction will occur.
4. Which of the following statements is/are TRUE? Oxidation and reduction
A. cannot occur independently of each other
B. accompany all chemical changes
C. describe the loss and gain of electron(s), respectively
D. result in a change in the oxidation states of the species involved
E. A, C, and D
5. What is the mass of a 6.761 mol sample of NaOH?
A. 40.00 g
B. 270.4 g
D. 5.916 g
E. 0.1690 g
C. 162.3 g
6. How many atoms of hydrogen are present in 7.63 g of NH3?
A. 2.70 × 1023
B. 1.52 × 1024
C. 1.38 × 1025
23
20
D. 8.09 × 10
E. 1.12 × 10
7. Equal masses (in grams) of hydrogen gas and oxygen gas are reacted to form water. Which substance is limiting?
A. Oxygen gas is limiting.
B. Hydrogen gas is limiting.
C. Water is limiting.
D. Nothing is limiting.
E. More information is needed to answer this question.
1
8. The drawings below represent flasks of aqueous solutions. Each pink dot represents a dissolved solute particle.
If you place solution D in a 500 mL flask and dilute to a volume of 500 mL, which flask best represents the new solution?
A. Solution A
D. Solution D
Solution A
500 mL
B. Solution B
E. Solution E
Solution B
500 mL
C. Solution C
F. Solution F
Solution C
500 mL
Solution D
250 mL
Solution E
250 mL
Solution F
250 mL
9. Which one of the following solutions has the largest concentration of H+ ions?
A. 0.100 M HCl
B. 0.100 M H2S
C. 0.100 M H2SO4
D. 0.200 M NaOH
E. 0.100 M CH3COOH
II. Nomenclature
If the name is given, please give the formula. If the formula is given, please give the name. (4 points each, spelling counts)
A. NH3
B. CdI2
C. Strontium chlorate
D. (NH4)2SO4
E. Co(NO2)2
F. CH3OH
III. Free Response
1. When the pH of a solution changes from pH = 2.00 to pH = 5.00, the concentration of H+ changes from _______________ to
_______________ and the concentration of OH- changes from _______________ to _______________ . (2 points per blank)
2
2. Combustion analysis of a compound that contains ONLY carbon and hydrogen (no oxygen) produced 23.118 g of carbon dioxide
and 4.729 g of water. Find the empirical formula for the compound. (12 points)
3. A 16.4-g sample of HF is dissolved in water to give 2.5000 × 102 mL of solution in a 250.00 mL volumetric flask. What is the
concentration of the solution? (6 points)
4. For each of the following compounds, list ALL of the following categories under which it falls (and no more): (10 points)
strong electrolyte, weak electrolyte, nonelectrolyte, insoluble, strong acid, weak acid, and strong base
A. NH3
B. HI
C. Fe(CH3COO)3
D. CsOH
E. Co2S3
F. CH3CH2CH2CH2OH
3
5. Determine the oxidation numbers of each element in each compound. (12 points)
A. O2
B. H2SO4
C. CaCr2O7
D. C3H8
6. What is the pH when 41.51 mL of 0.200 M NaOH is added to 25.00 mL of 0.150 M HCl? (12 points)
4
7. A 1.59-g sample of a metal chloride, MCl2, is dissolved in water and treated with excess aqueous silver nitrate. The silver chloride
that formed weighed 3.60 g. Determine the molar mass of M and identify the metal. (10 points)
MCl2(aq) + 2 AgNO3(aq) → 2 AgCl(s) + M(NO3)2(aq)
5
8. "Do you know the muffin man who lives on Drury Lane?"
When making muffins, the recipe calls for one teaspoon (or 4.60 g) of baking powder to make 12 muffins. Rumford Baking Powder
has the following composition:
30% (w/w) NaHCO3
30% (w/w) Ca(H2PO4)2•H2O
remainder corn starch (non reactive)
Baking powder reacts to make CO2(g) that makes the muffins rise via the following reaction:
14 NaHCO3 + 5 Ca(H2PO4)2H2O → 14 CO2 + Ca5(PO4)3OH + 7 Na2HPO4 + 18 H2O
A. Name NaHCO3 and Ca(H2PO4)2•H2O. (8 points)
B. If one teaspoon of baking powder is used to make a batch of 12 muffins, how many grams of CO2(g) are produced in each
muffin? For this problem, show all of your work. (14 points)
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Chemistry 400
Conversions and Equations
1 L = 1.057 qt
453.6 g = 1 lb
ºF = 1.8 º C + 32
1 m = 39.37 in
1 yd = 36 in = 3 ft
Na = 6.02 x 1023
1 gal = 4 qt
1 lb = 16 oz
1 calorie = 4.184 J
specific heat of water = 4.184 J/g °C
q = Energy = (mass) (Csp) (ΔT)
average atomic mass =
PO2 = (% O2) PT
λ=
€
E = hν
2
% yield = actual/theoretical × 100%
PT = P1 + P2 + P3 + …
λ=
$ 1 1'
E = −2.18 ×10 J Z && 2 − 2 ))
€
% n2 n1€
(
−18
€
(mass isotope 1)(%) + (mass isotope 2)(%) + (mass isotope 3)(%)
100%
P1 V1 / T1 = P2 V2 / T2
c
ν
1 qt = 4 cups
1 mile = 5280 feet
1 atm = 101.3 kPa = 1.013 bar = 14.7 psi
For gases: standard T = 273.15 K, P = 1 atm
h
KE = ½ mv2
mv
h = 6.626×10–34 J•s
c = 3.00×108 m/s€
1 L•atm = 101.325 J
PV=nRT
ΔxmΔv =
w = -P ΔV
h
4π
Mass of electron =
9.1×10–31 kg
Kw = [H3O+] [OH–] = 1.0×10–14
[H+] [OH–] = 1.0×10–14
C 1V 1 = C 2V 2
R=0.08206 L•atm/mol•K = 8.314 J/mol•K
Specific heat of ice: 2.09 J/g•°C
Specific heat of water: 4.184 J/g•°C
Specific heat of steam: 2.03 J/g•°C
Heat of fusion of H2O = Δ Hfus = 6.02 kJ/mol
Heat of vaporization of H2O = Δ Hvap = 40.7 kJ/mol
€
ΔT = m i K
π =iMRT
€
€
" P % −ΔHvap " 1 1 %
ln$ 2 ' =
$ − '
R # T2 T1 &
# P1 &
€
€
1
1 ppm = 1 x 10-6 g/mL
€
1 ppb = 1 x 10-9 g/mL