Chemistry 0500A - Practice Final KEY: (2011-Fall)
Only legible written responses in the examination booklet provided will be considered. No credit will
be given for answers which are not in the booklet. Marks will be deducted for incorrect information
added to an otherwise correct response. Show your work for all calculations. Answers without
supporting calculations will not be given full or any credit. When you are finished, submit all
materials, the exam and the exam booklet(s). Responses to the multiple choice section in Part II
must be in pencil and transferred correctly onto the electronic grade sheet to be graded. Some data
tables, equations and periodic table are provided for you. Read the questions carefully and good luck.
Part I: Demonstration
Part II: Short Answer
Example Question:
An unknown organic compound has a molar mass of 86.04 g/mol. An elemental analysis of the
unknown organic showed only the presence of the elements C, O and H. The following percent
composition were recorded for C 55.81% and H 6.98%. Determine the empirical and molecular
formula for the unknown organic compound.
The solution is as 55.81% C, 6.98% H and by default 37.21% is O if we assume 100%. Therefore a
100 g sample would be 55.81g C, 6.98g H and 37.21g is O. Dividing by the atomic mass of each
respectively to calculate there are 4.64 mols C, 6.92 mols of H and 2.33 mols O. The empirical formula
is found by divide mols of each element by the smallest value 2.33 and round to whole numbers.
1.99 or 2 C
2.97 or 3 H
1O
Empirical formula is C2H3O the formula mass is approximately half the value of the given molar mass
of 86.04 g/mol therefore the molecular formula is doubled the empirical formula.
C4H6O2
Part III: Multiple Choice:
Example Questions:
1) Which of the changes listed will shift the equilibrium to the right for the following reversible reaction?
SO3(g) + NO(g) + heat
↔
SO2(g) + NO2(g)
A) increase [SO3]
B) increase [SO2]
C) decrease temperature
D) increase volume
E) add a catalyst
2) What is the equilibrium constant expression for the following reaction?
4 NH3(g) + 5 O2(g)
↔
4 NO(g) + 6 H2O(g)
A) Keq = [NO] [H2O] / [NH3] [O2]
B) Keq = [NO]4 [H2O]6 / [NH3]4 [O2]5
C) Keq = [NH3] [O2] / [NO] [H2O]
D) Keq = [NH3]4 [O2]5 / [NO]4 [H2O]6
E) none of the above
3) What is the term for the energy necessary for reactants to achieve the transition state and form products?
A) heat of reaction
B) collision energy
C) activation energy
D) energy barrier
E) rate barrier
4) What is the term for the inexactness of an instrumental measurement?
A) accuracy
B) error
C) precision
D) uncertainty
E) none of the above
5) Which of the following unit factors is derived from 1 hour = 3600 seconds?
A) 1 hour/1 second
B) 1 second/3600 hours
C) 3600 hours/1 second
D) 3600 hours/3600 seconds
E) none of the above
6) Which of the following elements has the smallest atomic radius?
A) F
B) Cl
C) Br
D) O
E) S
7) What is the systematic name for NH4Cl?
A) tetraammonium chloride
B) ammonium chloride
C) ammonium tetrachloride
D) nitrogen tetrahydrogen chloride
E) none of the above
8) What is the coefficient of chlorine gas after balancing the following equation?
__Fe(s) + __Cl2(g)
→
__FeCl3(s)
A) 1
B) 2
C) 3
D) 4
E) none of the above
9) What is the density of fluorine gas, F2, at STP?
A) 0.589 g/L
B) 0.848 g/L
C) 1.18 g/L
D) 1.70 g/L
E) 22.4 g/L
10) Which of the following is an example of an Arrhenius acid?
A) Al(OH)3(s)
B) Ba(OH)2(aq)
C) RbOH(aq)
D) H2O(l)
E) none of the above
11) ) Apply the like dissolves like rule to predict which of the following solids is insoluble in water.
A) cholesterol, C27H46O
B) citric acid, C6H8O7
C) fructose, C6H12O6
D) glycine, CH2(NH2)COOH
E) lactic acid, CH3CH(OH)COOH
12) What is the mass of nickel(II) nitrate (182.71 g/mol) dissolved in 25.0 mL of 0.100 M Ni(NO3)2 solution?
A) 0.250 g
B) 0.457 g
C) 4.00 g
D) 45.7 g
E) 457 g
13) Consider the following liquids with similar molar masses. Predict which liquid has the highest boiling point
based only on vapor pressure data.
A) pentane (vapor pressure @ 20 °C = 430 mm Hg)
B) methyl acetate (vapor pressure @ 20 °C = 205 mm Hg)
C) butyl alcohol (vapor pressure @ 20 °C = 6 mm Hg)
D) propyl chloride (vapor pressure @ 20 °C = 300 mm Hg)
E) ethyl ether (vapor pressure @ 20 °C = 450 mm Hg)
14) Which of the following are types of crystalline solids?
A) ionic
B) metallic
C) molecular
D) all of the above
E) none of the above
15 ) If a volume of air at 375 K increases from 100.0 mL to 150.0 mL, what is the final Kelvin temperature?
Assume pressure remains constant.
A) 153 K
B) 250 K
C) 375 K
D) 344 K
E) 563 K