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CH1410 Practice Exam #4
Multiple Choice - Write the letter of the BEST CHOICE in the space provided. (YOU MUST INCLUDE A
SOLUTION PLAN. NO CREDIT WILL BE AWARDED FOR SIMPLY CHOOSING THE CORRECT
ANSWER FOR PROBLEMS WHICH INCLUDE A CALCULATION. (#’s 7-13, 15, 16, 21-26)) D
_____ 1. Consider the following n-alkanes: CH4, C2H6, C3H8, C4H10
Which of these would you expect to have the highest boiling point?
A) CH4
B) C2H6
C) C3H8
D) C4H10
A
_____ 2. Two compounds are considered as isomers if they have the
D
A) same molecular formula AND different structure.
B) same molecular formula AND same structure.
C) different molecular formula AND different structure.
D) different molecular formula AND same structure.
_____ 3. Name the following alkene:
A) 2-propyl-2-isobutene
B) 1-propyl-2-butene
C) 1,1,3-trimethyl-1-pentene
D) 3,4-dimethyl-2-pentene
CH3
CH3
C
C
H
CH3
CH
CH3
B
_____ 4. The combustion of alkanes, alkenes and alkynes produces:
A) water and carbon.
B) carbon dioxide and water.
C) carbon dioxide and hydrogen.
D) hydrogen and water.
_____ 5. Name the major functional group in the molecule pictured at right
B
A) alcohol
B) ester
C) carboxylic acid
D) ketone
O
C
H3C
CH3
O
C
_____ 6. Name the following alkane:
A) 2-ethyl-1,3-dimethyl propane
B) 3,3-dimethyl pentane
C) 3-ethyl pentane
D) isoheptane
CH3
CH2
CH
CH2
CH2
CH3
CH3
A 7. We dissolve 2.45 g of sugar in 200.0 g water. What is the mass percent of sugar in the solution?
_____
A) 1.21%
B) 1.23%
C) 2.42%
D) 123%
[(2.45)/(2.45+200.0)] x 100%= 1.21%
D
_____ 8. What is the mass percent of a sodium fluoride solution prepared by dissolving 0.64 moles of sodium fluoride (molar
mass = 41.99 g/mole) in 63.5 grams of water?
A) 26.9%
B) 42.3%
C) 70.3%
D) 29.7%
0.64 x 41.99 = 26.87 g NaF
[(26.87)/(26.87+63.5)] x 100% =29.7%
D
_____ 9.What is the molarity of a solution prepared by dissolving 10.7 g NaI (molar mass = 149.89 g/mole)in water to give
0.250 L of solution?
A) 42.8
B) 0.0714
-4
C) 2.86x 10
D) 0.286
10.7/149.89= 0.0714 mol NaI
0.0714 mol NaI/0.250 L = 0.286 M
A
_____10. How many grams of LiF would be present in 575 mL of 0.750 M LiF (molar mass = 25.94 g/mole) solution??
A) 11.2
B) 0.0338
C) 1.12 × 104
D) 19.9
(0.575 L) x(0.750 mol/L) x (25.94 g/mol)= 11.2 g LiF
D
_____ 11. What is the final concentration of a solution prepared by diluting 35.0 mL of 12.0 M HCl to a final volume of 1.20 L?
A) 0.504 M
M1 x V1 = M2 x V2 (12.0) x (0.035) = M1 x (1.20 L)
B) 3.50 M
C) 0.420 M
D) 0.350 M
M2 = 0.350 M
B
_____ 12. If you add 4.00 mL of pure water to 6.00 mL of 0.750 M NaCl solution, what is the concentration of sodium
chloride in the diluted solution?
A) 0.250 M
B) 0.450 M
C) 0.500 M
D) 1.13 M
(0.750) x (0.006) = M2 x (0.0100)
M2 = 0.450 M
A
_____13. How many mL of 0.218 M sodium sulfate react with exactly 25.34 mL of 0.113 M BaCl2 given the reaction:
BaCl2 (aq) + Na2SO4(aq) → BaSO4 (s) + 2NaCl (aq)
A) 13.1
B) 5.52
C) 24.6
D) 2.86
D
0.02534 L BaCl2 solution X 0.113 mol BaCl2
1.00 L BaCl2
1.00 L Na2SO4 solution
0.218 mol Na2SO4
X
X
1.00 mol Na2SO4
1.00 mol BaCl2
1000 ml
1.00 L
_____14. In the following reaction, label the conjugate acid/base pairs and choose A,B,C, or D.
NH4+ (aq) + H2O (aq) → NH3 (aq) + H3O+ (aq)
A) NH4+ is an acid and H2O is its conjugate base.
B) H2O is a base and NH3 is its conjugate acid.
C) NH4+ is an acid and H3O+ is its conjugate base.
D) H2O is a base and H3O+ is its conjugate acid.
mass % = (mass of solute/mass of solution)x100
Molarity = mol/L = M
X
= 13.1 mL
A
_____15. A 25.0 ml sample of 0.105 M HCl was titrated to an endpoint with 31.5 ml of NaOH. What is the concentration of
the NaOH?
A) 0.0833 M
B) 0.132 M
C) 0.105 M
D) 0.075 M
D
______16.Exactly 17.0 mL of a H2SO4 solution was required to neutralize 45.0 mL of 0.235 M NaOH. What was the
concentration of the H2SO4 solution?
H2SO4 (aq) + 2NaOH (aq) → 2H2O (l) + Na2SO4 (aq)
A) 5.63 M
B) 0.622 M
C) 0.00529 M
D) 0.311 M
D
_____17. Which of the following acids is a diprotic, weak acid?
A) sulfuric acid (H2SO4)
C) hydrobromic acid (HBr)
B) phosphoric acid (H3PO4)
D) carbonic acid (H2CO3)
A
_____18. What is the concentration of the hydroxide ion given that the concentration of the hydronium ion is 1.5 × 10-5 M?
A) 6.7 × 10-10 M
B) 1.5 × 109 M
C) 1.0 × 10-14 M
D) 1.0 × 10-19 M
([OH-]) x (1.5 x 10-5) = 1.0 x 10-14
[OH-] = 6.7 x 10-10
A
_____19. What is the pH of a solution that has a H⁺ concentration equal to 1.76 × 10-5 M?
A) 4.75
C) 0.22
B) 5.20
D) 10.20
pH = -log(1.76 x10-5 ) = 4.75
C
_____20. What is the [H⁺] in a solution that has a pH of 3.35?
A) 1 × 103.35 M
B) 2.2 × 103 M
C) 4.5 × 10-4 M
D) 3.35 × 10-14 M
[H+} = 10-pH = 10-3.35 = 4.5 x 10-4
C
_____21. Convert 1.50 atm to torr.
A) 760 torr
C) 1140 torr
B) 875 torr
D) 1000 torr
C
_____22. The volume of a gas is proportional to the temperature of a gas is known as
A) Avogadro's Law
C) Charles's Law
B) Ideal Gas Law
D) Boyle's Law
B
_____23. A balloon filled with 0.500 L of air at sea level is submerged in the water to a depth that produces a
pressure of 3.25 atm. What is the volume of the balloon at this depth?
(P1) (V1)= (P2) (V2)
A) 1.63 L
B) 0.154 L
C) 6.50 L
D)0.615 L
Molarity = mol/L = M
(1) (0.500)= (3.25) (V2)
pH = -log[H3O+]
[H3O+] = 10-pH
[H3O+][OH-] =
Kw = 1x10-14
C
_____24. A gas sample occupies 3.50 liters of volume at 20.°C. What volume will this gas occupy at 100.°C (reported to
three significant figures)? D
(V1)/ (T1)= (V2) /(T2)
A) 0.224 L
B) 2.75 L
C) 4.46 L
D) 17.5 L
(3.50)/ (293)= (V2)/ (372)
_____25. A balloon originally had a volume of 0.439 L at 44°C and a pressure of 729 torr. To what temperature must the
balloon be cooled to reduce its volume to 378 mL if the pressure remained constant?
A) 0°C
B) 38°C
C) 95°C
D) 273°C
(V1)/ (T1)= (V2) /(T2)
(0.439)/ (317)= (0.378)/ (T2)
B
_____26. A sample of helium gas initially at 37.0°C, 785 torr and 2.00 L was heated to 58.0°C while the volume expanded to
3.24 L. What is the final pressure in atm?
A) 517
B) 0.679
C) 1.79
D)3.21
(P1)(V1)/ (T1)= (P2)(V2) /(T2)
785/760 = 1.03 atm
(1.03)(2.00)/ (310)= (P2)(3.24)/(331)
A
_____27. A sample of 0.255 mole of gas has a volume of 748 mL at 28°C. Calculate the pressure of this gas.
(R= 0.0821 atm · L / mol · K)
A) 8.42 atm
B) 0.784 atm
C) 0.00842 atm
D) 7.84 × 10-4 atm
(P)(V)= (n)(R)(T)
(P)(0.748 L)= (0.255)(0.0821)(301)
A
_____28. What is the temperature (°C) of 2.48 moles of gas stored in a 30.0 L container at 1559 mm Hg?
(R= 0.0821 L atm/ mol K)
A) 302
B) 189
C) 29
D)-84
(P)(V)= (n)(R)(T)
1559/760 = 2.05 atm
(2.05 atm)(30.0 L)= (2.48 L)(0.0821)(T)
A
_____29. How many liters of oxygen are needed to exactly react with 1.24 moles of methane at STP?
CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)
A) 13.9 L
B) 27.8 L
C) 55.5 L
D) 60.5 L
1.24 mol x 22.4 L = 27.8 L O2
1/2 x 27.8 L = 13.9 L CH4
C
_____30. When 14.0 g of zinc metal (atomic weight = 65.39) reacts with excess HCl, how many liters of H2 gas are
produced at STP?
Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2 (aq)
A) 0.208 L
B) 0.416 L
22.4 L H2
= 4.80
14.0 g Zn X 1.00 mol Zn X 1.00 mol H2 X
C) 4.80 L
1.00
mol H2
1.00
mol
Zn
65.39
g
Zn
D) 9.60 L
P1V1=P2V2
V1/T1=V2/T2 P1/T1=P2/T2
Molar gas volume=22.4 L/mol at STP
PV=nRT
L H2
(R=0.0821 L-atm/mol-K)