Download Spring 2014

Chemistry 120
Exam 1
February 21, 2014
Name __________________
SHOW YOUR WORK. NO WORK, NO CREDIT
INCLUDE LABELS AND PROPER NUMBER OF SIG FIGS
Table of Constants
N A  6.022 x 1023
particles
mole
c  2.998 x 108
m
s
h  6.626 x 1034
J s
photon
0°C = 273.15 K
Up to 75% of the credit for a problem will be given for correctly setting it up, including labels on all numbers and proper number of
significant figures
On my honor, I pledge that I have upheld the Honor Code, and that the work I have done on this assignment has been honest, and
that the work of others in this class has, to the best of my knowledge, been honest as well.
Signed __________________________________________________________________________
If you feel you can’t sign this, contact the instructor (e-mail or in person)
(2 pts each) Multiple choice - circle the correct answer
1.
How many significant figures are there in the answer to the following problem? (8.881 × 2.100) + 0.590 = ?
A) one
2.
3.
a) Nd
d) none of these
b) Ni
24
Cr
b.
Cr +3
c.
24
Cr -3
d.
none of these
B) noble gas
C) alkaline earth metal
D) halogen
Which of the following elements has chemical properties similar to oxygen?
B) nitrogen
C) fluorine
D) hydrogen
Which pair of elements on the right represent isotopes?
B) C and D
C) A and B
25
21
D) A and C
Sc
A
21
25
Mn
B
Which of the following is NOT available in the safety island between the hood
banks?
a)
8.
24
Which group of the periodic table does lithium belong to?
A) A and D
7.
c) Co
Q.
An element containing 24 protons, 21 electrons and 28 neutrons will have the symbol:
A) sulfur
6.
D) four
60
27
A) alkali metal
5.
C) three
Identify the element designated by Q in
a.
4.
B) two
eyewash fountain
b) bandaids
c)
acetic acid for base spills
What is the symbol (metric system prefix) that represents the factor 10 -6?
a) n
b) μ
c) p
d) m
1
d) safety shower
27
21
Sc
C
25
23
V
D
9.
If hitting the bull’s eye is the desired result, the figure on the right represents
a) poor accuracy and poor precision.
b) poor accuracy and good precision.
c) good accuracy and poor precision.
d) good accuracy and good precision.
10. Which of the following elements is not a gas at room temperature?
a) Br
b) H
c) Cl
d) Xe
11. What is the name of the shaded group in the periodic table on the right?
a) alkali metals
b) alkaline earth metals
c) halogens
d) transition metals
12. What type of bonding is found in the compound NiSO4?
a) hydrogen bonding
b) metallic bonding
c) covalent bonding
d) ionic bonding
13. Which element below normally exists as a diatomic molecule?
a)
magnesium
b) phosphorus
c)
bromine
d) xenon
14. An beta (β) particle is
a) a neutron
b) a photon
c) an electron
d) a helium nucleus
15. How many electrons can a single d orbital hold?
a) 8
b) 2
c) 6
d) depends on the shell number (n)
16. In lab your group determined that the density of titanium was 4.32 g/ml. The accepted value is 4.51 g/ml. How many significant
figures of agreement are there between these two numbers?
a)
no agreement
b) 1
c)
2
d) 3
17. When Ba(NO3)2 dissolves in water, it breaks apart into how many ions?
a)
no ions
b) 2 ions
c)
3 ions
d) mor than 6 ions
18. If BiO3-1 is called bismuthate, then the formula for bismuthite would be
a)
BiO4-1
b) BiO3-1
c)
BiO2-1
d) BiO-1
19. (2 pts) Write the formula of the compound that results when N(CH3)4+1 combines with SnS3-2
20. (2 pts) What is the volume in the graduated cylinder on the right? ______________________
21. (3 pts each) Name the following compounds.
a.
Ca(ClO2)2
________________________________
b.
SO3
________________________________
2
22. (3 pts each) Write the formula for each of the following compounds.
a.
cobalt (III) hydroxide
________________________________
b.
nitrogen trifluoride
________________________________
23. (8 pts) The density of Zn is 7.14 g/cm3. What is the mass in grams of 1 mm3 of Zn?
24. (8 pts) The atomic mass of copper given on the periodic table is 63.55 amu. Copper consists of two naturally occurring isotopes. 63Cu
has a mass of 62.93 amu and an abundance of 69.2%. The other isotope then has an abundance of 30.8%. What is the mass of the
second isotope?
25. (8 pts) What is the percent of water in Pb(H2O)4Cl2?
3
26. (8 pts) How many grams of phosphorus (P) are there in 4 x 1016 molecules of P2O5?
27. An infrared light emitting diode (LED) produces light with a frequency of 2.85 x 1013 Hz.
a.
(8 pts) What is the wavelength of this light?
b.
(8 pts) If it takes 4.184 J of energy to raise the temperature of exactly one gram of water one degree Celcius, how many photons
from this LED are needed to raise the temperature of 250 g of water (about one cup) one degree Celcius?
4
Chemistry 120
Exam 2
Name __________________
print
March 21, 2014
SHOW YOUR WORK. NO WORK, NO CREDIT
INCLUDE LABELS AND PROPER NUMBER OF SIG FIGS
Table of Constants
N A  6.022 x 1023
particles
mole
c  2.998 x 108
m
s
h  6.626 x 1034
J s
photon
0°C = 273.15 K
Up to 75% of the credit for a problem will be given for correctly setting it up, including labels on all numbers and proper number of
significant figures
On my honor, I pledge that I have upheld the Honor Code, and that the work I have done on this assignment has been honest, and
that the work of others in this class has, to the best of my knowledge, been honest as well.
Signed __________________________________________________________________________
If you feel you can’t sign this, contact the instructor (e-mail or in person)
(2 pts each) Multiple choice - circle the correct answer
1.
Which of the following atoms with the specified electronic configurations would have the lowest first ionization energy?
A) [Xe] 6s2 4f14 5d10 6p1
2.
B) H3C–CH3
B) P
B) octahedral
C) square planar
D) trigonal bipyramidal
B) three σ bonds.
C) two π bonds and one σ bond.
D) three π bonds.
Which set of quantum numbers below (n, R, m R, ms) could belong to an electron in a 4p orbital?
B) (4, 1, –1, –1/2)
C) (4, 0, 0, ½)
D) (5, 4, 1, –1/2)
Which has the highest Zeff for its valence electrons?
A) P
8.
D) S
A triple bond is generally composed of
A) (5, 4, 4, ½)
7.
D) HC/CH
C) Sc
A) one π bond and two σ bonds.
6.
C) H2C=CH2
What geometric arrangement of charge clouds is expected for an atom that has five charge clouds?
A) tetrahedral
5.
D) [He] 2s2 2p3
Which of the following elements has the highest electronegativity?
A) As
4.
C) [Ne] 3s2 3p4
Which molecule contains the most easily broken carbon-carbon bond?
A) F2C=SiF2
3.
B) [Xe] 6s1
B) K
C) Si
D) Na
Which of the following elements would you predict to have an electron configuration that does not follow the normal filling pattern?
A) 34Se
B) 47Ag
C) 45Rh
D) 38Sr
1
9.
The number of sp2 hybrid orbitals on the carbon atom in CO3-2 (one resonance structure shown) is
A) two.
B) four.
C) one.
D) three.
10. The four spheres below represent Na+, Mg2+, F-1, and O2-, not necessarily in that order. Which sphere most likely represents the O-2
ion?
a) A
b) B
c) C
d) D
11. The orbital filling diagram for oxygen is shown on the right. What is the set of quantum numbers for the electron circled?
a.
n = 2, R = 0, mR = 0, ms = -1/2
b.
n = 2, R = 1, mR = -1, ms = -1/2
c.
n = 2, R = 2, mR = 0, ms = -1/2
d.
n = 1, R = 1, mR = 1, ms = -1/2
12. Which of the following is not an acceptable Lewis structure?
A)
B)
C)
D) all are acceptable structures
13. NO2 has 5 + 2*6 = 17 valence electrons. Which statement about NO2 is correct?
A) Since it cannot form octets with an odd number of electrons, the molecule doesn’t exist.
B) The molecule exists because nitrogen can form stable 3-electron bonds.
C) The molecule does exist, but is pretty reactive because one atom does not have an octet.
D) Nitrogen cannot form oxides.
14. (4 pts) CIRCLE ALL THAT APPLY. Which of the following are NOT appropriate attire for lab.
A) tank top
B) tennis shoes
E) calf-length dress
C) USD sweatshirt
F) skin-tight stretch pants
D) boots with knee-length skirt
G) baseball cap
H) sandals with sox
15. (3 pts) Label each of the compounds below as ionic, polar covalent, purely covalent.
CaO __________________
CO __________________
O2 __________________
16. (3 pts each) Name the following compounds:
(NH4)2CrO4
_____________________________
Hg2SO4
_____________________________
17. (3 pts each) Write formulas for the following compounds:
manganese dioxide
_______________________
arsenic (V) perchlorate
________________________
18. (5 pts) What is the electron configuration for 46Pd? You may start with an inert gas core if you wish.
2
19. (8 pts each) Draw the Lewis structures, including any resonance structures, for:
ClO2+1
IF3
20. (1 pt each blank) Fill in the blanks for each Lewis structure.
Shape __________________________
Shape at C 1 __________________________
Polar (yes/no) __________________________
Polar (yes/no) __________________________
Hybrid ________________________________
Hybrid of C 1 ________________________________
H-Se-H bond angle(s) ____________________________
O-C-O bond angle at C 1 ____________________________
21. (5 pts) One possible Lewis structure for C2H4Cl2O is shown on the right. Draw a geometric isomer of this structure.
22. (5 pts) What is the formal charge on nitrogen in
? Show your work.
3
23. The electron configuration of 57La is [Xe] 6s2 5d1.
a.
(4 pts) Is +1 a stable charge for La? Explain your reasoning.
b.
(4 pts) Is La+3 paramagnetic or diamagnetic? Explain your reasoning.
24. (8 pts) The ionization energy of Ti is 658.8 kJ/mole. What is the lowest frequency of light with enough energy to ionize a Ti atom?
4
Chemistry 120
Exam 3
Name __________________
print
April 11, 2014
SHOW YOUR WORK. NO WORK, NO CREDIT
INCLUDE LABELS AND PROPER NUMBER OF SIG FIGS
particles
mole
J
Cp (H 2 O) = 4.184
g  deg
N A  6.022 x 1023
Table of Constants
m
Js
c  2.998 x 108
h  6.626 x 1034
0°C = 273.15 K
s
photon
L  atm
L  torr
J
R = 0.08206
= 62.36
= 8.314
K  mole
K  mole
K  mole
Up to 75% of the credit for a problem will be given for correctly setting it up, including labels on all numbers and proper number of
significant figures
On my honor, I pledge that I have upheld the Honor Code, and that the work I have done on this assignment has been honest, and
that the work of others in this class has, to the best of my knowledge, been honest as well.
Signed __________________________________________________________________________
If you feel you can’t sign this, contact the instructor (e-mail or in person)
(2 pts each) Multiple choice - circle the correct answer
1.
What is the oxidation number of the sulfur in S2O3-2?
a)
2.
d) –2
NH4I
b) H3PO4
c) CaCO3
d) RbNO2
CaCO3
b) NH3
c) Ca(OH)2
d) NaHSO4
NaCl
b) NH3
c)
H2SO4
d) Ba(OH)2
The pictures on the right represent aqueous solutions of three acids HX, HY, HZ with water
molecules omitted for clarity. Unshaded spheres represent hydrogen atoms or ions and gray
spheres represent the anions. Which of the three is the strongest electrolyte?
a)
6.
+3
Which of the following is a strong base in water?
a)
5.
c)
Which of the following cannot act as a base in water?
a)
4.
b) +2
Which of the following is insoluble in water?
a)
3.
0
HZ
b) HY
c) HX
d) all three are the same strength
Which one of these reactions is primarily an acid/base reaction?
a.
Cu(NO3)2 + 2 NaOH ! Cu(OH)2 + 2 NaNO3
b.
CuO + H2SO4 ! CuSO4 + H2O
c.
Cu + 4 HNO3 ! Cu(NO3)2 + 2 NO2 + 2 H2O
d.
Cu(OH)2 + heat ! CuO
1
7.
The reaction C6H12O6 (s) + 6 O2 (g) ! 6 CO2 (g) + 6 H2O (l) is best classified as a(n)
A) acid-base reaction.
8.
9.
B) double replacement reaction.
C) oxidation-reduction reaction.
D) precipitation reaction.
The mixing of which pair of reactants will result in a precipitation reaction?
A) H2S (aq) + Ni(OH)2 (aq)
B) Na3PO4 (aq) + NH4Cl (aq)
C) CsI (aq) + NaOH (aq)
D) K2SO4 (aq) + Co(NO3)2 (aq)
Which species is the reducing agent in the reaction Zn (s) + Cu2+ (aq) ! Cu (s) + Zn2+ (aq)?
a)
Zn(s)
b) Zn2+ (aq)
c)
d) Cu2+ (aq)
Cu(s)
10. For which of the following should the standard enthalpy of formation ΔHf° be zero at 25 °C?
a)
Li2 (g)
b) Li (l)
c)
Li (s)
d) all the above
11. Cooking and baking involve chemical reactions. Under standard conditions these reactions would be considered
a) endothermic reactions.
b) precipitation reactions.
c) exothermic reactions.
d) spontaneous reactions.
12. For the freezing of liquid ethanol,
A) ΔH is negative and ΔS is positive.
B) ΔH is positive and ΔS is positive.
C) ΔH is positive and ΔS is negative.
D) ΔH is negative and ΔS is negative.
13. When heated, mercury(II) oxide decomposes into elemental mercury and oxygen: 2 HgO (s) ! 2 Hg (l) + O2 (g). For this reaction
ΔH° is 181.6 kJ/mole and ΔS° is 216.4 J/(K·mole). This reaction will
a) be spontaneous at any temperature.
b) be spontaneous at only at some temperatures above 25°C.
c) be spontaneous at only at some temperatures below 25°C.
d) never be spontaneous at any temperature.
14. You used NaOH solutions in several labs. The primary safety hazard for this reagent is
a.
produces hazardous fumes so it must be used in the hood.
c.
none, it is relatively safe.
d.
b.
causes severe burns to skin and eyes.
flammable, keep away from flames.
15. (3 pts each) Name the following compounds.
HF
______________________________
Ni(IO2)2
__________________________________
16. (3 pts each) Write formulas for the following compounds.
carbonic acid
______________________
lead (IV) permanganate
2
___________________
17. The following molecular reaction takes place in aqueous solution
HNO3
+ (NH4)3PO3
!
H3PO3
a.
(4 pts) Assign physical states (s, l, g, aq) to each reactant and product.
b.
(8 pts) Write and balance the corresponding net ionic equation.
+
NH4NO3
18. Consider the balanced reaction: Mg + 2 HCl ! MgCl2 + H2. When 3.00 x 10-3 mole of Mg was added to 50.00 mL of 0.1000 M
HCl in lab, 1.50 x 10-3 mole of H2 was collected.
a.
(8 pts) Was the Mg or the HCl the limiting reagent? Explain your reasoning or show your work.
b.
(4 pts) What was the percent yield of hydrogen?
19. (12 pts) Balance the following redox reaction which takes place in basic solution.
ClO-1 (aq) +
Cr(OH)4-1 (aq) !
3
CrO4-2 (aq) +
Cl-1 (aq)
20. An oxide of phosphorus is found to be 43.64% P and 56.36% O.
a.
(10 pts) What is the empirical formula for this compound?
b.
(2 pts) The molar mass of the compound found by mass spectrometry was 288 g/mole. What is the molecular formula for this
compound?
21. (12 pts) When 1.50 g of Ba (s) is added to 100.00 g of water in a container open to the atmosphere, the reaction shown below occurs
and the temperature of the resulting solution rises from 22.00°C to 33.10°C. If the specific heat of the solution is 4.18 J/(g · °C),
calculate ΔH for the reaction.
Ba (s) + 2 H2O (l) ! Ba(OH)2 (aq) + H2 (g)
4
Chemistry 120
Exam 4
Name __________________
print
May, 7, 2014
SHOW YOUR WORK. NO WORK, NO CREDIT
INCLUDE LABELS AND PROPER NUMBER OF SIG FIGS
Up to 75% of the credit for a problem will be given for correctly setting it up, including labels on all numbers.
Equations and Constants Given on the ACS Exam
R = 8.314 J mol 1 K 1 = 0.0821 Latmmol1 K 1
F = 96500 Cmol1 = 96500 J V 1 mol1
N A = 6.022 x 1023 mol1
c = 2.998 x 108 ms 1
h = 6.626 x 1034 J s
Ea
0°C = 273.15 K
12
M 
rateA
= B
rateB
 MA 
RT
0.05916
ln(Q)
Nernst Equation: E = E° ln(Q) Nernst Equation at 25°C: E = E° n
nF
1
1
Integrated Rate Laws zero: [A] = [A]0 - kt first: ln[A] = ln[A]0 - kt
second:
= kt +
[A]
[A]0
Arrhenius Equation: k = Ae
RT
Graham's Law of Effusion:
On my honor, I pledge that I have upheld the Honor Code, and that the work I have done on this assignment has been honest, and
that the work of others in this class has, to the best of my knowledge, been honest as well.
Signed __________________________________________________________________________
If you feel you can’t sign this, contact the instructor (e-mail or in person)
(2 pts each) Multiple choice - circle the correct answer
1.
Three identical flasks are at standard temperature and pressure. Flask A contains CH4, flask B contains CO2, flask C contains N2.
Which flask contains the largest number of molecules?
A) flask A
2.
B) flask B
B) 763 mm.
C) 745 mm Hg.
D) none of the options.
Which of the noble gases should show the greatest deviation from the ideal gas law at high pressures?
A) He
4.
D) All flasks contain the same number of molecules.
Hydrogen gas from a reaction is collected over water and the apparatus adjusted so the internal pressure is at atmospheric pressure.
If the atmospheric pressure is 745 mm Hg and the vapor pressure of water is 18 mm Hg, the pressure of the hydrogen gas is
A) 727 mm Hg.
3.
C) flask C
B) Rn
C) Ar
D) All deviate equally.
Which statement about real gases is true?
A) The mass of the gas particles is zero.
B) Forces of attraction and repulsion exist between gas particles at close range.
C) The behavior of real gases can be exactly predicted using the ideal gas law.
5.
D) The volume of the gas particles is zero.
The primary safety concern when running reactions that generate hydrogen is that hydrogen
A.
is flammable.
B. is an acute poison.
C. is a suspected carcinogen.
1
D. has a penetrating odor and is corrosive.
6.
A sample of gas is placed in a sealed cylinder with a moveable piston as shown in diagram (1).
The initial pressure, number of moles, and temperature of the gas are noted on the diagram.
Which diagram (2)-(4) most closely represents the result of doubling the pressure while keeping
the temperature and number of moles of gas constant?
A) diagram (2)
7.
b. CO
D) none of them
c. HCl
d. NaCl
Which of the molecules below should be most soluble in CS2 (Lewis structure S=C=S).
a)
9.
C) diagram (4)
Which of the following show the weakest interaction between molecules?
a. O2
8.
B) diagram (3)
b)
c)
Na2S
d)
Which of the following does NOT exhibit hydrogen bonding?
a)
HF
b) CH3NH2
c)
HOCH2CH2OH
d) CH2F2
10. Which of the intermolecular forces is the most important contributor to the surface tension of liquid SF4?
a) dipole-dipole forces
b) ion-dipole forces
c) hydrogen bonding
d) dispersion forces
11. Which of the following should have the highest vapor pressure at room temperature?
A.
B.
C.
D.
12. Starting with the reaction shown below at equilibrium, which change in conditions (stress) will result in formation of more product?
CoCl4-2 (aq) + 6 H2O (l) ! Co(H2O)6+2 (aq) + 4 Cl-1 (aq)
a)
add NaCl
b) evaporate some of the water
c)
add AgNO3
d) add Co(NO3)2
13. The equilibrium constant is equal to 5.00 at 1300 K for the reaction 2 SO2 (g) + O2 (g) W 2 SO3 (g). If initial concentrations are [SO2]
= 4.0 M, [O2] = 4.0 M, and [SO3] = 4.0 M, the system is
a) not at equilibrium and will shift to the right (products) to achieve an equilibrium state.
b) not at equilibrium and will remain in an unequilibrated state.
c) not at equilibrium and will shift to the left (reactants) to achieve an equilibrium state.
d) at equilibrium.
14. Picture (1) represents the equilibrium mixture for the endothermic reaction A + B W 2 AB at 298 K. Which picture represents the
equilibrium mixture at 400 K?
a) (2)
b) (3)
c) (4)
d) none of them
2
15. Which one of these salts will form a basic solution upon dissolving in water?
A. NaCl
B. NaNO2
C. NH4NO3
D. AlBr3
16. Which of the following will form an acidic solution when dissolved in water?
a. NaBr
b. CaBr2
c. AlBr3
d. none of these form an acidic solution
17. Bicarbonate (common name for HCO3-1) is an amphiprotic ion. If its Ka is 4.7 x 10-11 and its Kb is 2.3 x 10-8, will a solution of
bicarbonate be acidic, basic, or neutral?
a) acidic
b) basic
c) neutral
d) can’t tell from the information given
18. What statement is most consistent for an acid with a pH = 3?
a) It is twice as strong as an acid with a pH of 6.
b) It is half a strong as an acid with a pH = 6
c) It is one thousandth as strong an acid with a pH of 6.
d) It is one thousand times as strong as an acid with a pH = 6.
19. (3 pts each) Name the following compounds.
KAl(SO4)2
______________________________
HNO2
__________________________________
20. (3 pts each) Write formulas for the following compounds.
copper (I) carbonate
______________________
hydrosulfuric acid
________________________
21. (8 pts) Write the equilibrium constant expression for the balanced, net ionic reaction below.
3 Cu (s) + 2 NO3-1 (aq) + 8 H+1 (aq) ! 3 Cu+2 (aq) + 4 H2O (l) + 2 NO (aq)
Keq =
22. (11 pts) The gases NO2 and SO3 are blamed for acid rain. How do these compounds, which contain no hydrogen, make rain acidic?
3
23. (11 pts) Pure oxygen can be produced in the lab by heating KClO3 in the presence of a catalyst (balanced reaction given below). If
1.2255 g of KClO3 is completely decomposed in a sealed 250.0 mL flask and the container allowed to cool to 22.5 °C, what will be
the pressure of the oxygen in that container?
2 KClO3 (s) ! 2 KCl (s) + 3 O2 (g)
24. (11 pts) What is the pH of 2.00 x 10-3 M Ba(OH)2?
25. (11 pts) A 0.100 M solution of nitrous acid has a pH of 2.17. What is the Ka for nitrous acid?
4