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Chemistry 20
Final Review 3-8 Answer Key
1. The major entities present when K2SO4(s) is placed in a water environment are:
a) K+(aq), SO4(aq), H2O(l)
b) K(s), SO4(aq), H2O(l)
c) K+(aq), SO42-(aq), H2O(l)
d) K(s), SO4-(aq), H2O(l)
2. Railway officials indicated that the spill of sulfuric acid from derailed tanker cars
in Parry Sound, Ontario would not happen again – the problem was fixed. The
statement issued is classified as a/an
a) technological perspective
b) scientific perspective
c) ecological perspective
d) economic perspective
3. A formation reaction is one of several general reaction types. Identify the
formation reaction for sulfur dioxode.
a) S8(s) + 8 O2(g)  8 SO2(g)
b) S(s) + O2(g)  SO2(g)
c) SO2(g) + H2O (l)  H2SO3(aq)
d) SO2(g) + ½ O2(g)  SO3(g)
4. The experimental design of most directly determining the mass of solute in a
specific volume of solution is called
a) titration
b) crystallization
c) filtration
d) distillation
5. In the analysis section of an investigation report,
a) qualitative and quantitative evidence is listed.
b) a new relationship between variables is predicted
c) the evidence is subjected to mathematical treatment.
d) the prediction is judged to be verified, falsified or inconclusive.
6. According to our present theory, which of the following chemical formulas
represents a pure substance containing covalent bonds?
a) NaCl
b) NiF2
c) PbO2
d) SO3
7. According to the restricted Quantum Mechanics Theory, an atom has an electron
energy level distribution of 2e-, 8e-, 7e-. The symbol for the particle is
a) F
b) Fc) Ar
d) Cl
8. The predicted amount of sodium carbonate, Na2CO3(s) required in a chemical
analysis is 0.130 mol. The mass that should be measured is: 13.8 g.
m = nM = (0.130 mol) (105.99 g/mol) = 13.8 g
9. The mass of sodium oxalate required to prepare 100.0 mL of 0.256 mol/L solution
for an analytical chemistry lab is 3.43 g.
n = CV = (0.256 mol/L)(0.1000 L) = 0.0256 mol
m = nM = (0.0256 mol)(134.00 g/mol) = 3.43 g
10. A chemical analysis of a consumer H2O2(aq) solution showed that 0.540 g of
hydrogen peroxide was present in 15.0 mL. The molar concentration of the
hydrogen peroxide solution is 1.06 mol/L.
n = m/M = 0.540 g/34.02 g/mol = 0.0159 mol
C = n/V = (0.0159 mol)/(0.0150 L) = 1.06 mol/L
11. Complete the Analysis section of the following investigation report.
Problem:
What is the molar concentration of lead(II) nitrate in the toxic waste solution?
Experimental Design:
A 10.0 mL sample of the toxic waste solution was reacted with an excess of
sodium bromide in solution. The lead(II) bromide precipitate was separated by
filtration, dried, and its mass determined.
Observations:
Mass of filter paper = 0.78 g
Mass of filter paper plus dried precipitate = 1.92 g
Analysis:
Mass of ppt = (Mass of filter paper & ppt) – (Mass of filter paper)
Mass of ppt = (1.92 g) – (0.78 g)
Mass of ppt = 1.14 g
12. A substance was dissolved in water to form a conducting solution that does not
affect litmus. This evidence indicates a/an
a) acid substance that has ionized in solution
b) neutral ionic substance that has dissociated in solution
c) base substance that has dissociated in solution
d) base substance that has ionized in solution
13. The pH of some tap water was measured to be 8.00. The hydrogen ion
concentration is
a) 1.0 x 108 mol/L
b) 1.0 x 10-8 mol/L
c) 8.0 x 10-8 mol/L
d) 8.0 mol/L
14. The different shapes of balloons are possible because air is a gas that
a) has neither a fixed shape nor volume
b) is highly compressible
c) diffused readily
d) mixes easily with other gases
15. What volume is occupied by 0.35 mol of helium at SATP?
a) 71 L
b) 8.7 L
c) 0.35 L
d) 0.014 L
16. In an experiment, 0.25 g of hydrogen at 92 kPa and 30°C is produced. What
volume of hydrogen is expected?
a) 3.4 L
b) 3.1 L
c) 0.68 L
d) 0.34 L
17. If 5.31 g of potassium iodide in solution are mixed with an excess of lead(II)
nitrate solution, the mass of precipitate formed is
a) 0.0320 g
b) 3.69 g
c) 7.37 g
d) 14.7 g
18. The mass of lithium fluoride contained in 100 mL if 2.00 mol/L solution is
a) 2.33 g
b) 5.19 g
c) 6.58 g
d) 7.71 g
19. State weather each of the following statements about weak acids are true or false.
a) Good conductors of electricity F
b) Turn red litmus paper blue F
c) Are above the hydronium ion in the Chem Data Booklet Acid Table F
20. What colors are the following ions in an aqueous solution?
a) iron (III) orange-yellow
b) Ni2+(aq) blue-green
21. What colors are the following ions in a flame test?
a) calcium red
b) K+(aq) violet
22. Describe how to prepare 100 mL of a 0.40 mol/L MgSO4 solution from a
2.0 mol/L stock solution of the substance.
C1V1 = C2V2
(2.0 mol/L)V1 = (0.40 mol/L)(100 mL)
V1 = 20 mL
1)
2)
3)
4)
Add approximately 50 mL of distilled water to the volumetric flask.
Measure 20 mL of MgSO4(aq) (stock solution) using a pipette.
Transfer the stock solution slowly into the volumetric flask while mixing.
Add pure water, and then use a medicine dropper to set the bottom of the
meniscus on the calibration line.
23. Convert the solubility of baking soda (6.9 g/100 mL) to molar solubility (mol/L).
NaHCO3(s)
6.9 g x 1000 mL x
mol = 0.82 mol
100mL
1L
84.01 g
L
24. A balloon is inflated in an air conditioned room at 27oC and has a volume of
4.0 L. It is heated to a temperature of 57oC. What is the new volume of the
balloon if pressure is kept constant?
V2 = V1T2 = (4.0 L)(330.15 K) = 4.4 L
T1
(300.15K)
26. A balloon containing hydrogen gas at 20oC and 100 kPa, has a volume of 7.50 L.
Calculate the volume of the balloon after it rises 10 km where the temperature
drops to -36oC and air pressure to 28 kPa. Assume no hydrogen escapes.
V2 = P1V1T2 = (100kPa)(7.50 L)(237.15 K) = 22 L
T1P2
(293.15 K)(28 kPa)
27. If 0.177 mol of silver nitrate in solution is mixed with 0.261 mol of iron chloride
what is the limiting and what is the excess reagent? What is the mass of each
product formed?
3 AgNO3(aq) + FeCl3(aq)  Fe(NO3)3(aq) + 3 AgCl(s)
n = 0.177 mol n = 0.261 mol
Finding moles of Fe(NO3)3:
n = 0.177mol x 1mol/2mol = 0.0590mol│ n = 0.261mol x 1mol/1mol = 0.261mol
AgNO3 is the limiting reagent, FeCl3 is the excess reagent
mFe(NO3)3 = nM = (0.0590 mol)(241.88g/mol) = 14.3 g
_______________________________________________
nAgCl = 0.261 mol x 3mol/1 mol = 0.783 mol
mAgCl = nM = (0.783 mol)(143.32 g/mol) = 112 g
28. What is the molar concentration of the sulfuric acid solution below?
Titration of 10.0 mL of H2SO4 (aq) with 0.259 mol/L NaOH(aq)
Trial
1
2
3
Final buret reading (mL)
19.5
37.6
21.2
Initial buret reading (mL)
0.9
19.5
2.7
Volume of NaOH added (mL)
18.6
18.1
18.5
4
37.5
19.1
18.4
H2SO4(aq) + 2NaOH(aq)  2HOH(l) + Na2SO4(aq)
V = 10.0 mL C = 0.259 mol/L
C=?
V = 18.5 mL
nNaOH = CV = (0.259 mol/L)(18.5 mL) = 4.79 mmol
nH2SO4 = 4.79 mmol x 1 mol/2 mol = 2.40 mmol
CH2SO4 = n/V = (2.40 mmol)/(10.0 mL) = 0.240 mol/L
29. Draw the Lewis (electron) Dot diagram, VSEPR structure, and name the correct
shape for the following:
a. NH3
b. N2
c. CHCl3
d. CH3CN
trigonal
pyramidal
linear
tetrahedral
tetrahedral &
linear
30. Write the balanced chemical equation, complete ionic equation, and net ionic
equations to represent: calcium chloride and sodium carbonate reacted together.
CaCl2(aq) + Na2CO3(aq)  2NaCl(aq) + CaCO3(s)
Ca2+(aq) + 2Cl-(aq) + 2Na+(aq) + CO32-(aq)  2Na+(aq) + 2Cl-(aq) + CaCO3(s)
Ca2+(aq) + CO32-(aq)  CaCO3(s)
31. Complete the following table:
Element
Number of
Lone pairs
Cs
0
Si
0
Number of
Bonding electrons
1
4
32. Complete the following table:
Molecular
Number of
Substance
Electrons
Cl2
34
BrF
44
CH3OH
18
C2H5F
26
London
Dispersion
☻
☻
☻
☻
Dipole-Dipole
Hydrogen
Bonding
X
X
☻
X
X
☻
☻
☻
33. Complete the following chart (watch for significant digits):
[H3O+]
pH
a/b/n
[OH-]
pOH
a/b/n
0.56 mol/L
0.25
acid
3 x 10-3 mol/L
2.5
base
7.050 x 10-7mol/L
6.1518
acid
2.75 x 10-14 mol/L
13.561
acid