Download Final Study Guide (Semester 2) Answer Key

Final Study Guide (Semester 2) Answer Key
Chemstry / Bly
Ch. 8
1. Consider this reaction:
CuSO4(aq) + 2KOH(aq)  Cu(OH)2(s ) + K2SO4(aq)
Which compounds above are strong electrolytes? CuSO4 , KOH , K2SO4
a. Which chemical above is not soluble in water? Cu(OH)2
c. Which chemical above is the precipitate? Cu(OH)2
2. Solutions of Barium nitrate and potassium sulfate are mixed.
***The first thing you should do when solving this is look at the common ion chart and
write down all the ions. It’s much easier than looking them up again for each question.
a. Write the balanced molecular equation. Include phase symbols.
Ba(NO3)2(aq) + K2SO4(aq) BaSO4(s) + 2KNO3 (aq)
Switch the cations in the reactants to make two products that are new ionic compounds.
If one of the products is not soluble (check the solubility chart p245—you can use this on
the test), it is the precipitate. Write (s) on the insoluble chemical. Sometimes both are
insoluble.
b. Write the balanced complete ionic equation. Include phase symbols.
Ba2+(aq) + 2NO32-(aq) + 2K+(aq) + SO42-(aq)  BaSO4(s) +2NO32-(aq) + 2K+(aq)
*Don’t forget the charges of the ions!
c. List the spectator ions: NO32- K+
*The spectator ions are the ions that do not make a precipitate.
*Don’t forget the charges when you write the spectator ions!
d. Write the balanced net ionic equation. Include phase symbols.
Just write it the same as the complete ionic equation, but without the spectator ions.
Ba2+(aq) + SO42-(aq)  BaSO4(s)
3. In the equation below, how many electrons does silver lose? 1.
2Ag + 2HCl  2AgCl + H2
*Silver forms a 1+ cation, which means it lost one negatively charged electron.
Classify each of the following reactions based on their driving forces: as a. an oxidationreduction reaction, b. acid-base reaction or c. precipitation reaction. (Write the letter a-c).
4. b HNO2 (aq) + KOH(aq)  KNO2 (aq) + H2O(l)
5. c K2SO4(aq) + BaCl2(aq)  2KCl(aq) + BaSO4(s)
6. a Mg(s) + I2(g)  MgI2(s)
Classify each of the following as a. combustion, b. synthesis or c. decomposition. Some
may have more than one possible answer.
7. a and b 2Fe(s) + 3O2(g)  Fe2O3(s)
8. b Ca + Cl2  CaCl2
9. c H2CO3(g)  H2O(g) + CO2(g)
Ch. 9
1. Answer the following for this equation:
3NO2(g) +
H2O(l) 
2 HNO3(aq) +
NO(g)
If 2.8 mol nitrogen dioxide react with excess water, how much nitric acid will be
made?
1.9 mol HNO3
2. You can purify manganese from manganese oxide by reacting it with aluminum. 334
grams manganese (IV) oxide (MnO2) react with 62.2 grams aluminum and make 84.1
grams manganese (Mn) and some aluminum oxide. The balanced equation is:
3MnO2 + 4Al  3Mn + 2Al2O3
a. What is the limiting reactant (reagent)? (Show a calculation that proves which is
the limiting reactant).
MnO2 = 3.84 mol
Al = 2.31 mol
To react with 3.84 mol MnO2, 5.12 mol Al is needed. There is not enough Al, so Al =
limiting reactant.
b. Calculate the theoretical yield of manganese in grams.
Use the mol of Al you have (2.31 mol) to calculate the grams of manganese produced.
95.2 g Mn
c.
Calculate the percent yield of manganese.
= actual/theoretical * 100 = 88.3%
10. If you mix NaOH and HCl in the following volumes, which reaction would you
expect to have the highest change in temperature?
A
B
C
D
E
Volume Acid
(± 0.3 mL)
5
10
15
20
25
Volume of NaOH
(± 0.3 mL)
20
20
20
20
20
Ch. 10
11. Define these terms: enthalpy, The law of conservation of energy (1st law of
thermodynamics), internal energy, petroleum, fossil fuels, Second Law of
Thermodynamics.
12. Give an example of an endothermic reaction.
Dissolving some salts in water, such as sodium chloride.
13. Give an example of an exothermic reaction.
Combustion of a hydrocarbon.
14. Draw a diagram of an exothermic reaction. Label the a. potential energy of the
reactants, b. potential energy of the products and c. the energy released to the
surroundings.
15. Draw a diagram of an endothermic reaction. Label the potential energy of the
reactants, the potential energy of the products and the energy absorbed from the
surroundings.
Like the previous question, but draw the energy of the reactants lower than the energy of
the products.
16. Are the random motions of molecules faster in hot tea (60 ºC) or a cold can of coke (5
ºC)?
The random motions are faster in hot tea.
17. A system does 12 kJ of work and absorbs (= receives) 24 kJ of heat. Calculate the
change in internal energy.
12 kJ
18. Convert 4.91 x 10-9 calories to kilojoules. 1 cal = 4.18 J
2.05 x 10-11 kJ
19. Using a candle, 1.43 kj of heat is applied to a 240 gram piece of metal and the
specific heat is 0.34 J/g ºC. Calculate the change in temperature in ºC.
Q/sm = ∆T = 17.5 ºC
20. For the reaction
S + O2  SO2 ∆H = -296 kJ/mol
Calculate the change in enthalpy when 22.02 grams of sulfur (S) are burned with
excess oxygen.
- 203 kJ
21. Given this data:
2S(s) + 3O2(g)  2SO3(g)
∆H = -790.4 kJ
2SO2(g) + O2(g)  2SO3(g) ∆H = -198.2 kJ
Calculate ∆H for this reaction:
S(s) + O2(g)  SO2(g)
Show your work.
-271.1 kJ
22. Name six uses for fractions of petroleum: (p341)
23. Answer the following for a distillation tower.
a. A substance will condense when it reaches a height where the temperature is
the same as the boiling point of the substance.
b. The hottest part of the tower is at the ( top / bottom ). The coolest part is
at the ( top / bottom ).
c. Which chemical would condense first, heptane (7 carbons) or decane (10
carbons)?
24. Name one commercial item made from petroleum. What petroleum product is used
to make it?
Basketballs are made from man-made rubber (from petroleum). Go to
http://www.adventuresinenergy.org/Oil-and-Natural-Gas-in-Your-Life/index.html for
more ideas.
Ch. 20
25. How many valence electrons does a carbon atom have? 4
26. How many covalent bonds can each carbon atom form? 4
27. How is ethanol produced in nature?
Yeast makes alcohol by the fermentation of sugar.
28. Be able to write the molecular formula of alkanes, alkenes and alkynes with 1-10
carbon atoms. Example: what is the molecular formula of hexane?
C6H14
29. Is hexene saturated or unsaturated?
Unsaturated
Name molecules containing hydrogen and carbon by the IUPAC system rules. Examples:
30. Name these:
a. Hexane
b. 2,3-dimethyl hexane
H
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
C
C
C
H
H
H
H
H
H
H
H
C
C
C
C
H
H
H
C
H
H
H
c. 3-methyl-1-butyne
d. 4,5-dimethyl-2-hexene
CH3
CH
CH
CH3
CH3
CH
CH
CH3
e. Methylcyclobutane
CH3
g. 3,4-dimethyl-3-phenyl octane
CH3
CH2
C
CH
CH2
CH3
CH3
CH2
CH2
CH3
h. methylcyclohexane
Give the IUPAC and common name of substituted benzenes. Example:
31. IUPAC systematic name: 1,2-dimethylbenzene
Common name: o-dimethylbenzene
CH3
CH3
32.
Name organic molecules containing halogens and oxygen.
33. Name these:
a. 3-bromo-1-butene
b. 2,2-dimethylpentanoic acid
CH3
Br
CH3
CH3
CH
CH
CH2
C
CH3
O
CH2
CH2
C
OH
c. 2-butanol
CH3
d. 2-butanone
CH
CH2
O
CH3
OH
e. methyl phenyl ether
O
C
CH2
CH3
CH2
CH2
CH3
CH3
f. Butanal
O
CH3
CH
Be able to draw structural formulas of alkanes, alkenes, alkynes, alcohols, ethers,
aldehydes, ketones, carboxylic acids and esters from the name. Examples:
34. 7, 7-diethyl 8,6,6-trimethyl 1-nonene
35. 4-methyl 2-pentyne
36. 2-pentanone
37. Methyl propyl ether
38. ethanal
39. 2-propanol
40. Decanoic acid
41. Propyl methyl ester
Be able to identify the functional group (circle it) and identify the molecular class.
Example:
42. For the following, circle the functional group and write the class of functional
group it is (alcohol, ether, aldehyde, ketone, carboxylic acid or ester). Do NOT
write the IUPAC name.
a. Class: alcohol
b. Class: ester
O
CH3
CH2
CH2
O-H
CH3
C
O
CH3
43. Be able to draw isomers of an alkane and explain why they are isomers. Example:
Draw heptane. Then draw two isomers of it. Explain why they are isomers.
Your drawings should have three structural formulas: heptane and two branched
molecules with the molecular formula of C7H16. “They are isomers because they have
the same number of each type of atom and different structures.”
Be able to predict the product of any type of chemical reaction we have learned (a.
substitution reaction b. dehydrogenation reaction c. Hydrogenation d. Halogenation)
and identify the reaction type.
Examples: For the following, name the type of chemical reaction and draw the structural
formula of the products.
a. substitution reaction b. dehydrogenation reaction c. Hydrogenation d. Halogenation
44. Reaction type: a
CH3—CH2—CH3 + Br2
CH3-CH2-CH2Br + HBr
45. Reaction type: d
CH2
CH
CH2
CH3
+ Br2 
CH2
CH3
+ H2
CH2Br—CHBr—CH2—CH3
46. Reaction type: c
CH2
CH
CH3—CH2—CH2—CH3
47. Reaction type: b
CH3—CH2—CH3
CH2=CH—CH3
Draw the products produced by a condensation reaction between an alcohol and
carboxylic acid. Example:
48. Write the structural formula of the ester that is made from propanoic acid and 1octanol.
49. Acrylonitrile can make polymers that are used in paints and clothing fabric, including
the fabric used in some of Bly’s clothes. Bly is allergic to wool, so he is happy that
he can buy clothes made of acrylic polymer. Draw the dimer formed from two
acrylonitrile molecules.
+

Ch. 21
50. Explain the difference between fibrous and globular proteins.
Fibrous proteins give structure to parts of the body. Example: Muscles. Globular
proteins are small balls of polypeptides that do different jobs in the body. For example,
they send messages.
51. Draw a peptide linkage between glycine and alanine.
52. How does the side chain affect the structure of the protein? (Hint: polarity).
When the protein folds, the hydrophilic side groups face outside the protein,
while the hydrophobic side groups mostly face inside.
53. Compare the alpha helix and beta pleated sheet. Describe their shapes and how they
influence the properties of proteins.
The alpha helix forms a spiral
(you can draw it if you can’t explain it in words). A pleated sheet makes a zig-zag
plane (you can draw it)
An alpha helix make stiff structures like your hair. Pleated sheets are strong but
flexible. Your muscles are made from proteins that have pleated sheets, for
example.
54. Describe how cysteine influences tertiary structure.
Cysteine can hold protein folds in place with a disulfide linkage (-S-S-)
55. Explain the difference between primary, secondary and tertiary structure.
Primary structure is the order of amino acids, which have hydrophilic and hydrophobic
side groups that can influence the structure. The secondary structure is folding over short
distances, which can make an alpha helix or a pleated sheet. Tertiary structure is the
folding over larger distances.