Download exam2gc1sum11+key

☰





Search
Explore
Log in
Create new account
Upload
×
Summer 2011
Chemistry 1411
EXAM # 2
Activity Series of Metals in Aqueous Solution
1
CHEM 1411 Exam # 2A
Name:________________________________
(Chapters 4,5,6, and 7)
Score:
Part I- ( 3 points each) - Please write your correct answer next to each
question number, DO NOT CIRCLE.
____ 1. Compare the rates of effusion of CO2 & SO2, rCO2/rSO2
A. CO2 will effuse 1.45 times faster
C. SO2 will effuse 1.45 times faster
B. CO2 will effuse 1.21 times faster
D. SO2 will effuse 2.12 times faster
____ 2. Consider the following redox reaction: 4NH3 + 5O24NO + 6H2O
Which of the following statements is correct?
A. N is reduced, NH3 is oxidizing agent
C. N is reduced, O is oxidized
B. O is oxidized, O2 is reducing agent
D. N is oxidized, O2 is oxidizing agent
____ 3. If 145 g of KNO3 were added to water to make 1,500 mL of solution,
what would be the molarity of the resulting solution?
A. 0.956 M
B. 1.43 M
C. 0.0967 M
D. 10.3 M
____ 4. Calculate the molarity of the solution formed by diluting 50.0 mL of
0.436 M NH4NO3 to 250.0 mL.
A. 21.8 M
B. 0.459 M
C. 0.0872 M
D. 11.5 M
_____5. Which of the following compounds is a weak electrolyte?
A. NH4Cl
B. HF
C. HCl
D. KOH
_____6. What is the chemical formula of the salt produced by the
neutralization of nitric acid with Barium hydroxide?
A. BaNO3
B. Ba2NO4
C. Ba2NO3
D. Ba(NO3)2
C. -3
D. 4
_____7. What is the oxidation number of N in NaNO2?
A. -1
B. 3
_____8. Iron is more active than silver but less active than zinc. Which one
of the following reactions will occur?
A. Fe + 2Ag+  Fe+2 + 2Ag
C. 3Ag + Fe+3 3Ag+ + Fe
B. Fe + Zn+2Fe+2 + Zn
D. Zn+2 + 2Ag Zn + 2Ag+
_____9. Based on the solubility rules, which of the following is insoluble?
A. CuSO4
B. CuS
C. CuCl2
D. Cu(NO3)2
_____10. 34.62 mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H
2SO4 solution. What is the molarity of H2SO4(aq)?
A. 0.105M
B. 0.0523 M
C. 0.209 M
D. 0.219 M
_____11. Calculate the density, in g/L, of chlorine (Cl2) gas at STP.
A. 0.0213 g/L
B. 3.16 g/L
C. 1.44 g/L
D. 1.58 g/L
_____12. Determine the molar mass of Freon-11 gas if a sample weighing 0.597
g occupies 100.0 mL at 95°C, and 1.316 atm.
A. 137 g/mol
B. 384 g/mol
C. 70.9 g/mol
D. 35.3 g/mol
_____13. Calculate the partial pressure of O2 in a gas mixture of 7.81 mol
N2, 2.09 mol O2, and 0.10 mol Ar that has a total pressure of
770 torr.
A. 0.209 torr
B. 621 torr
C. 161 torr
2
D. 4.85 atm
_____14. Which of the following has the highest rms velocity?
A. N2(g) at 298K
B. N2(g) at 398 K
C. O2 at 298 K
D. O2 at 398 K
_____15. What is the energy in joules of a mole of photons associated with
light of wavelength 486 nm?
A. 2.46 x 105J
B. 5.82 x 1010J
C. 4.09 x 10-19J
D. 6.80 x 103J
_____16. A hot metal pan at 90°C weighing 363 g was immersed in 1000 g of
water at 22.0°C. The final temperature of the pan
and water is 26.9 °C. Calculate the specific heat of the metal. The specific
heat of water is 4.184 J/g-°C.
A. 2.82 J/g·oC
B. 0.895 J/g·oC
C. 355 J/g·oC
D. 1.49 J/g·oC
____ 17. The thermochemical equation for the combustion of styrene, C8H8,
under 1 atm pressure and 25°C is the following. Find the
standard enthalpy of formation of styrene at 25°C. (Given: ΔH°f[CO2(g)] = –
394 kJ/mol, ΔH°f[H2O(l)] = –286 kJ/mol)
C8H8 + 10O2(g) → 8CO2(g) + 4H2O(l) ΔH°rxn = –4439 kJ/mol
A. 143 kJ/mol
B. -143 kJ/mol
C. 8735 kJ/mol
D. –3759 kJ/mol
____18. A gas is allowed to expand doing 5 J of work. If the gas absorbs 250
J of heat from the surroundings, what is the change in
internal energy?
A. 255 J
B. – 255 J
C. 245 J
D. -245 J
____19. Determine the heat given off to the surroundings when 9.0 g of
aluminum reacts according to the equation
2Al + Fe2O3 → Al2O3 + 2Fe, ΔH°rxn= –849 kJ
A. 7.6 x 103 kJ
B. 2.8 x 102 kJ
C. 1.4 x 102 kJ
D. 5.6 x 102 kJ
_____20. The standard enthalpy of formation, ∆Hf, of which of the following
is zero?
A. O3(g)
B. Br2(l)
C. H2O(l)
D. He2(g)
PART II- ( 5 points each) Please show all your work.
21. Consider the electronic transition from n = 2 to n = 5 in the hydrogen
atom.
a. Is light absorbed or emitted?
b. Calculate the energy, the frequency and wavelength (in nm) of the photon
involved.
22. Physical states have to be included for both equations in a & b for full
credit.
a. Complete the following reaction Pb(NO3)2 (aq) + NaCl(aq) 
b. Write the complete ionic equation
c. Identify the spectator ions
3
23. Calculate the heat change in kJ/mol NH4Cl from the following information.
When 6.134 g of NH 4Cl is added to 65.0 of g water
in a coffee-cup calorimeter at 24.5°C, the temperature rose to 30.4°C. Assume
that the calorimeter absorbed very little heat amount
of heat and that the specific heat of solution = 4.18 J/g·°C.
24. What is the pressure exerted by a mixture of 8.00 grams of acetylene,
C2H2, 10.0 grams of ethylene, C2H4, and 12.0 grams of
ethane, C2H6, placed in a 500 mL flask at 50°C.
25. What volume of H2 is formed at 25°C and 769 mm Hg when 6.0 g of Al is
treated with excess NaOH?
2NaOH + 2Al + 6H2O → 2NaAl(OH)4 + 3H2(g)
4
Bonus Question ( 10 points) - Please show all your work
Calculate ∆H for the reaction:
C2H2(g) + 2H2(g)  C2H6(g)
∆H =?
from the following thermochemical equations:
1.
2.
3.
C2H6(g) + (7/2) O2(g)  2CO2(g) + 3H2O(l) ∆H = -1560 kJ
2C2H2(g) + 5O2(g)  4CO2(g) + 2H2O(l) ∆H = -2599 kJ
H2(g) + (1/2) O2(g)  H2O(l)
∆H = -286 kJ
Key to CHEM 1411 Exam # 2
Part I
1. B
2. D
3. A
15. A
16. B 17. A
4. C
18. C
5. B
19. C
6. D
20. B
7. B
8. A
9. B
10. B
11. B
12. A
13. C
Part II
21. a absorbed
∆E = 2.18 x 10-18 x (4-1-25-1) J = 4.58 x 10-19 J
 = 4.58 x 10-19 J/(6.63 x 10-34Js) = 6.90 x 1014 s-1
 = 3 x 108 m s-1/( 6.90 x 1014 s-1) = 4.34 x 10-7m = 434 nm
22. Pb(NO3)2(aq) + 2NaCl(aq)  PbCl2(s) + 2NaNO3(aq)
b. Pb+2(aq) + 2NO3-(aq) + 2Na+(aq) + 2Cl-(aq)  PbCl2(s) +2NO3-(aq) + 2Na+(aq)
c. NO3-(aq), Na+(aq)
23. mass of solution = 71.134 g; heat change of solution = 71.134g x 4.18
J/g·°C x 5.9 °C = 1.75 x 103J;
heat change of reaction = -1.75 x 103J; moles of NH4Cl used = (6.134/53.50)
mol = 0.115 mol;
Heat change in kJ/mol NH4Cl = -1.53 x 104J/mol = -15.3 kJ/mol
24. ntotal = (8/26.04)mol + ( 10.0/28.06) mol + (12.0/30.08) mol = 1.06 mol;
P = 1.06 x 0.0821 x 323/0.500 atm = 56.4 atm
25. 6.0 g Al = 0.222 mol Al; 0.222 mol Al used = 0.222 x 3/2 mol H 2 formed =
0.334 mol H2 formed = n;
V of H2 = 0.334 x 0.0821 x 298/(769/760) L = 8.07 L
Bonus Question
Reverse equation 1
1. 2CO2(g) + 3H2O(l) C2H6(g) + (7/2) O2(g)
∆H = +1560 kJ
Divide equation 2 by 2
2. C2H2(g) + (5/2)O2(g)  2CO2(g) + H2O(l)
∆H = -2599/2 kJ
Multiply equation 3 by 2
3. 2H2(g) + O2(g) 2 H2O(l)
∆H = -286 x 2 = -572kJ
Add all three steps, simplify and add the heats
2CO2(g) + 3H2O(l) + C2H2(g) + (5/2)O2(g)+ O2(g) + 2H2(g)  C2H6(g) + (7/2)
O2(g) + 2CO2(g) + H2O(l)+ 2 H2O(l)
C2H2(g) + 2H2(g)  C2H6(g)
∆H ={1560 + (-2599/2) + -572}kJ = -311.5 kJ
5
14. B
Download
1. Science
2. Chemistry
exam2gc1sum11+key.doc
CHEMISTRY 123-01 Practice exam #3 – answer key October 05
INDIANA STATE UNIVERSITY
PERIOD 3 COMPOUNDS AN INTRODUCTION TO A guide for A level students
Density
Dual Nature of Light λν= c λ= wavelength ν = frequency of light c
1st Semester Exam in High School Chemistry
Chemistry
Chemistry
Radiation Tutorial Questions
Heat in Chemical Reactions
Heat in Chemical Reactions
Thermodynamics Notes
II - International Indian School, Riyadh.
Heat PowerPoint
studylib © 2017
DMCA Report