2006_explanations.pdf

8/14/2019 2006_explanations.pdf

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2006 Take Home Quiz Explanations to the answers provided.

1. Which gas should not be collected over water because of its high solubility in water?(D) HCl

HCl is a STRONG ACID. Strong deals with 100% dissociation (high solubil i ty).

2. A student wishes to measure 17.3 mL of a standard solution. This can be done best usingwhich container?

(C) 25 mL buret

A buret is marked in 0.1 mL increments. Burets are used for ti trationswhich

requi res very precise measurements. The other options are 25 mL beaker. One

should only use a beaker to place items within. The markings on the side are a

guide to approximate volumes one should NEVER use the markings for

precision. 25 mL volumetr ic pipet would be a very good option I F the buret were notl isted. Pipets are typicall y marked to a half mL OR there is a single mark that

represents the 25 mL volume (very precisely). The last option, 25 mL volumetr ic flask

fall s in the same category as a beaker.

3. In a familiar classroom demonstration, concentrated H2SO4is added to a beaker

containing some sucrose (C12H22O11), to produce a column of carbon. In this reaction

the H2SO4is acting primarily as a

(B) dehydrating agent

Concentrated sul fur ic acid has a very powerfuldehydrating property, removing water

(H2O)from othercompounds.

View video: http: //www.youtube.com/watch?v=5Ib3MuOThTg& feature=related

4. Aqua regia, the reagent that can be used to dissolve gold, is a 3:1 mixture of which acids?

(C) hydrochloric and nitric acids

Themixtur e is formed by freshly mixing concentratedni tri c acid andhydrochloricacid,usually in a volume rati o of 1:3. I t was named so because it can dissolve the so-

called royal ornoble metals,gold andplatinum.
http://en.wikipedia.org/wiki/Dehydration_reactionhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Compoundhttp://www.youtube.com/watch?v=5Ib3MuOThTg&feature=relatedhttp://www.youtube.com/watch?v=5Ib3MuOThTg&feature=relatedhttp://en.wikipedia.org/wiki/Mixturehttp://en.wikipedia.org/wiki/Nitric_acidhttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Noble_metalshttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Platinumhttp://en.wikipedia.org/wiki/Platinumhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Noble_metalshttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Hydrochloric_acidhttp://en.wikipedia.org/wiki/Nitric_acidhttp://en.wikipedia.org/wiki/Mixturehttp://www.youtube.com/watch?v=5Ib3MuOThTg&feature=relatedhttp://en.wikipedia.org/wiki/Compoundhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Dehydration_reaction


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5. The solubility of a solid in H2O at different temperatures

is indicated in the accompanying diagram. What mass

of the solid will crystallize when 40. mL of a solution

that is saturated at 80 0C is cooled to 20 0C?

(A) 12 grams

The chart is for 100 mL of water. I f the solution onlyhas a volume of 40. mL we then need to create a

ratio for this problem.

At 800C, approximately 90. grams of the solid can dissolve. At 20

0C, approximately 60

grams. This was determined by the foll owing equationmass of solid dissolved:

Mass of solid = [ (temperature)(0.5) + 50]

Therefore for a 40. mL use the above equation and modify it:

Mass of solid = (40/100) [(temperature)(0.5) + 50]

@ 200C: (40/100) [(20)(0.5) + 50] = 24 grams

@ 800C: (40/100) [(80)(0.5) + 50] = 36 grams

36 grams24 grams = 12 grams

6. A student is asked to determine the degree of hydration of a salt by finding the mass of a

clean dried crucible and lid followed by the mass of the crucible and lid containing asample of the salt. The crucible, lid and salt are heated in a Bunsen burner flame,

cooled, and weighed. If the crucible, lid and salt are heated only once instead of the

recommended three times, what will be the effect of the degree of hydration compared

with the actual value?

(B) too low

Heating the salt only one time will evaporate some of the water off of the salt

(hydrate), but a MI NIMUM of three heatings shouldbe performed to ensure thatall of the water is being removed. Whi le heating the salt dur ing the f ir st heating, one

should notice water droplets on the lid (cover glass), if there is no water droplets on

the lid on the second heating then you have removed all the water (this is rare). The

third heating is used to validate that the mass is no longer decreasing as the salt

(hydrate) is heated. However, one must not heat the substance too much or one could

decompose the substancewhich is not the purpose of this lab.


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7. Which is the net ionic equation for the reaction when 0.10Msolutions of silver nitrate

and sodium sulfide are mixed?

(D) 2 Ag+1 (aq) + S-2(aq) Ag2S (s)

Well , the choice given was not total ly accurate, the answer that I gave is correct. The

net ionic equation li sts the ions involved in forming the precipitate. Never include

spectator ions in the NET I ONI C equation. Spectators are ni trate ions, NO3-1

, andsodium ions, Na

+1.

8. Magnetite, which has the formula Fe3O4, is comprised of iron(II) oxide and iron(III)

oxide. What is the ratio of iron(II) ions to iron(III) ions in magnetite?

(B) 1:2

I ron(I I ) oxide is FeO, ir on(I I I ) oxide is Fe2O3. I f Fe3O4is the resul t of the two iron

oxides being mixed together, i t would stand to reason that iron(I I I ) oxide has twice as

many ir on atoms (with a +3 charge) than the iron(I I ) oxide molecule since there are

two atoms of ir on(I I I ) in the molecular formulaand only one ir on(I I ) in its

molecular formula.

9. C3H8 + 5 O2 3 CO2 + 4 H2O

What is the total mass, in grams, of the products when 2.20 grams of propane is burned in

excess oxygen?

(D) 10.2 grams

Stoichiometry !

3 8 22

3 8 2

12.20 3 44.016.587

44.094 1 3

mol C Hg mol CO gg CO

g mol C H mol CO

3 8 22

3 8 2

12.20 4 18.0163.5955

44.094 1 1

mol C Hg mol H O gg H O

g mol C H mol H O

Total mass of the products = 6.587 grams + 3.5955 grams = 10.18 grams


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10. What volume, in mL, of concentrated sulfuric acid (18.0 M H2SO4) is needed to prepare

2.50 L of a 1.00Msolution?

(D) 139 mL

F irst we need to calculate how many moles are in the 2.50 li ters of the 1.00 M solution:

2 42 4

2.50 12.5L mol H SO mol H SO

L

Next, calculate the volume needed (from the STOCK soluti on) to make the dil ute 1.00

M solution.

2 42 4

2 4

2.5 1000139

18 1

mol H SO mLLmL H SO

mol H SO L

11. The bromide impurity in a 2.00 gram sample of a metal nitrate is precipitated as silverbromide. If 6.40 mL of 0.200 M AgNO3solution is required, what is the mass

percentage of bromide in the sample?

(C) 5.11 %

13

1

3

6.40 1 0.200 1.00 79.90.1023

1000 1.00 1

mL L mol AgNO mol AgBr g g Br

mL L mol AgNO mol Br

1

0.1023 100% 5.11%2.00

g Brg XBr

Please reali ze that this question is not asking you to i denti fy the metal (for thi s metall ic

ni trate), yet the question is stating that there is some bromine that has attached itself

to th is compound.


5/22

12. Under which conditions is the solubility of oxygen gas in water the greatest?

(B) High (Pressure) and Low (Temperatures)

Know the difference between solid solubility and gas solubility. These two phases

actual ly behave very dif ferently when the temperatur e of the solu tion is raised (soli ds

do not care about pressur e (with solubil i ty)). Gases are more soluble when the

solution is cooler (not as much energy in the solution)where soli ds are more soluble

in warmer solutions. Lets consider why. Gases are already a gas (thank you M r.

Obvious!)which means that adding more energy to a gas wil l cause the gas to move

even f aster (higher molecular velocity) causing the gas to escape the soluti on more

easily. Placing the gas in a cooler solution wi ll cause the gas to slow down and

possibly stay in solu tion. Solids behave oppositely of gases - because solids (individual

ions or molecules once in solu tion) are able to absorb more energy which causes them

to move more freely in the solution.

13. Which pure compounds form intermolecular hydrogen bonds?

(A) I only

Hydrogen bonds take place between MOLECULESnot

between a hydrogen atom and ni trogen (or oxygen, or

f luor ine). Hydrogen bonding is 1) with a polar molecule that 2) has a hydrogen atom

bonded (polar covalently (not sharing the electrons equal ly between atoms

(INTRAmolecular bonding))) to NOF (nitrogen, oxygen, & fluorine). Hydrogen

bonds are the strongest INTERmolecular bonds (bonding between molecules) for

molecular (non-metal with non-metal) compounds.

H2S is a polar compound with hydrogen. However, H2S can onl y have Dipole-Dipole

intermolecular bonding. CH4, methane, is a NON-polar compound and can only

have (London) Dispersion forces.


6/22


7/22

16. If the circles represent molecules, which diagram provides the best molecular level

representation of a pure solid in the process of melting?

(B) I n the solid state, the molecules are

touching each other and not

moving around. When a solid

begins to melt, the solid wil l melt in

stagesthe whole soli d does not

change to a liquid at one moment.

Di agram (A), could represent a

sublimation. The diagram shows

that some of the molecules have so

much energy that they are creating

a great distance away from the other molecules that are sti l l in the soli d state

(touching each other). (C) is a solid. Al l the molecules are touching each other . (D)

may be attempting to represent two crystals (not one soli d). Therefore, (B) is the best

representative for a soli d phase melti ng.

17. Which substance boils at the highest temperature?

(D) CCl4

Al r ight, I am not a big fan on this question! The wording is not the best either (too

much is left to interpretation.) I believe this question is asking at a particular

temperature (which happens to be high) which substance will boil. We all should

recognize that thi s the only non-polar compound (l isted). Non-polar compounds are

held together wi th weak intermolecular for ces (London Dispersion forces)the other

molecules have dipole-dipole forces (between the molecules). INTERmolecular

forces determine if a substance exists as a soli d, liquid, or gas at a parti cular

temperature.


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18. What can be concluded about the substance represented

by this phase diagram?

(B) The solid is more dense than the liquid.

The layout f or the (given) phase diagram isfor most

substances. Waters phase diagram (below) does not

look thi s way because

when water is soli d, the soli d has a lower density than

when water is in a liquid phase. The major dif ference

is (from this diagram and waters diagram) is that

from the Triple point (the pressure and temperature

that the substance is at equi li bri um wi th al l th ree

states) upward, the line angles to the right. The

angli ng to the r ight indicates that the solid is denser

than when a li quid.

19. A chemical reaction is carried out twice with the same quantity of reactants to form the

same products but the pressure is different for the two experiments. Which does not

change?

(A) Kp

At a specifi c temperature (this is a HUGE concept!! ! ), the equil ibr ium constant wil l

remain the same value (same ratio of products to reactants). The equi li bri um

constant only changes when the temperature changes. Equilibrium 101

20. Which of these conversions has a positive S?

(A) I only

Positive S deals with the system becoming

more organized. In I the combustion of ANYTHING will cause an increase in

disorder forming li quids and gases. The other two options I I ) condensation of Br2(g)

indicates that the gas is becoming more organized by becoming a li quid. And I I I )

precipitation of AgCl (s), indicates that sil ver ions and chlori ne ions are coming

together to form a precipi tateor two things forming one thing.


9/22

21. Given these reactions:

A 2B H = +40 kJB C H = -50 kJ

2C D H = -20 kJCalculate H for the reaction;

D + A 4 C

(C) - 40 kJ

22. Hydrazine, N2H4, contains a NN single bond and 4 NH bonds. Use the bond

energies to calculate H in kJ for the reaction; N2 + 2 H2 N2H4.(C) 98 kJ


10/22

23. An ice cube of unknown mass at 0 0C is added to 265 grams of H2O at 25.000C in a

calorimeter. If the final temperature of the resulting H2O is 21.700C, what is the mass of

the ice cube?

(B) 8.63 g

24. Which reaction is spontaneous at all temperatures at standard pressure and concentration?

(B) exothermic reaction with an increase in entropy

Al though pressure and concentration are not the real i ssue, one should know that for aspontaneous reaction to occur, Gibbs Free Energy, G, must have a negative value.

The only way that the reaction wil l be spontaneous at all temperatures is for the

enthalpy (heat) to be exothermic (negative H), and for the entropy (disorder) to be

positive (increasing the disorder).


11/22

25. When 100. mL of 1.0 M HCl is added to a 2.0 gram piece of CaCO3, CO2is produced ata certain rate. Which of the changes below will NOT increase the rate of this reaction?

(D) adding 150. mL of 1.0 M HCl in place of 100. mL of 1.0 M HCl

This question asks to discuss the other options and why (D) i s the best choice.

For (A), increasing the concentration wil l increase the rate of the reaction. I ncreasing

the concentration wil l increase the rate of a reaction. This question is not discussing a

zero order reactant (there would be more in formation if this were the case).For (B), heating increases the rate of a reaction. Heating allows the particles to move

at a higher velocity thus allowing the coll isions to occur more easily and more often.

For (C), increasing the sur face area of a reactant wil l increase the rate of the reaction.

I ncreasing the sur face area allows parti cles to react more easil y than only allowing the

outer most portion of the substance to react before allowing the inner sur face a chance

to coll ide with the other reactant particles.

26. 2 N2H4 (g) + N2O4(g) 3 N2(g) + 4 H2O (g)If N

2H

4(g) disappears at a rate of 0.12 molL-1min-1, at what rate does N

2(g) appear?

(C) 0.18 molL-1min-1

Rate Stoichiometry !! !

2 4 2 2 4

2 4

0.12 3 0.18

min 2 min

mol N H mol N mol N H

L mol N H L

27. Use the data to determine the orders of A and B in the reaction: A + B products

(B) Rate = k [A]2[B]


12/22

28. 2 NO (g) + Cl2(g) 2 NOCl H = -38 kJIf the activation energy for the forward reaction is 62 kJ. What is the activation energy

for the reverse reaction?

(D) 100 kJ

29. What is the order of a reaction if the rate constant has the units Lmol-1sec-1.

(C) second

Rate = molar ity per uni t of time

2

2

2 2 2;

sec sec sec

mol L LRate MRate k A k

M L mol molA

30. An iron catalyst is used in the Haber process in which gaseous N2and H2react to

produce NH3. What is the role of this catalyst?(A) It provides a pathway with a lower activation energy.

To explain thi s answer, one would need to discuss the other options.

(B) Adding something to a reaction that is not in the overall balanced equation and

thus not in the equil ibr ium expression, WOULD NOT affect the equil ibr ium

constant. Catalysts could (may) appear in the Rate Law, but catalysts wil l not appear

in the equil ibr ium constant.

(C) I ron cannot raise the kinetic energies of the reactants if i ron is acting as a

catalyst. Catalysts LOWER the energy needed to form the activated complex.

(D) I ron is the NOT interacting with the PRODUCT. The catalyst is assisting the

reactants in forming the activated complexwhich eventually forms the product(s).


13/22

31. 2 NO2(g) + 7 H2(g) 2 NH3(g) + 4 H2O (l)

What is the correct equilibrium expression for this reaction?

2

3

2 7

2 2

c

NHA K

NO H

Products over reactants. Do not include soli ds or l iquids in the expression! Al so, be

sure to express the coefficient as an exponent withi n the expression.

32. N2O4(g) 2 NO2(g)

The equilibrium reaction shown is endothermic as written. Which change will increase

the amount of NO2at equilibrium?

(C) increasing the volume of the container

When a gas system is at equi l ibrium and the volume of the system is increased, the

equil ibr ium system will shi ft in the dir ection that wil l increase the number of

particles in the system. This occurs because the system has a certain pressure at

equil ibr ium, and when the systems volume changes, the pressure of the system wil l

change (because there is more room for the particles to move around which reduces

the number of coll isions on the walls of the container).

33. Which weak acid has the strongest conjugate base?

(A) acetic acid (K

a= 1.8 x 10

-5

)

Of the acids listed, acetic acid has the lowest Kavalue. The lower the Kavalue for the

acid, the greater the Kbfor the conjugate base of that acid. I n th is case, the acetate

polyatomic ion wi l l have a the highest Kbvalue (the strongest base). Stronger

substances (acid, base, or salt) wi l l have a greater the dissociation in water.


14/22

34. What is the pH of a 0.20MHA solution (Ka= 1.0 x 10-6) that contains 0.40MNaA?

(D) 6.30

HA

H+1

A-1

I 0.20 ~ 0 0.40

C - x +x +x

E 0.20 - x

[ H+1

] 0.40 + x

1 1 1 1

60.40 0.40

1.0 100.20 0.20

a

H A H x HK

HA x

6

1 71.0 10 0.20

5.00 100.40

H

pH = - l og [ H

+1] = - log 5.00 x 10

-7= 6.30

35. A 0.1 M solution of which salt will have a pH less than 7 ?

(B) NH4Br

Less than 7 indicates an acidic solution. Know how to calculate salt pH (as acid or

basic) without doing any calculations. Recall that conjugates of strong acids and

conjugates of strong bases do not change the pH. Know the six strong acids. Know

the strong bases (solubil i ty rules). Ammonia, NH3, is a weak base. Conjugates of

weak bases will cause the solu tion to become more acidic. NH4+1is a conjugate of

ammonia. I n (D), NaO2CCH3, may not be somethi ng you recognize, however the

sodium atom is a conjugate of a strong base, and will do nothing to change the pH

the O2CCH2-1is a conjugate of some type of acid (not a strong acid). This conjugate

is of a weak acid which wil l behave as a base (making the pH higher).


15/22

36. What is the [ Mg+2] in 0.10 M NaF that is saturated with

MgF2at 250C?

(D) 6.4 x 10-7M

MgF2

Mg+2

2 F-1

I - 0 0.10

C - - x - 2x

E -

- x 0.10 - 2x

2 2 22 1 9

0.10 2 0.10 6.4 10spK Mg F x x x

9

7 22

6.4 106.4 10

0.10x Mg

37. Which change represents an oxidation?

(B) VO+2 VO3-1

Oxidation involves a loss of electrons, and the element becomes more posi tive.

2 H2O + VO+2 VO3

-1+ 4 H

+1+ e

-1

38. What is the oxidation number of Mo in MoO2Cl2?

(D) +6

One must assume that we are looking at an ionic compound. Wi th the options given

(as answers: 0, +3, +5, +6), Mo could not be neutral when bonded to non-metals.

Al so, the other options would be dif f icult to support therefore, each oxygen must

have a -2 charge and each chl orine must have a -1 charge.


16/22

39. What is the coefficient for H+1when the half equation is balanced with the smallest

whole number coefficients?

__ S-2 + __ H2O SO2 + __ H+1 + __ e-1

(B) 4

__ S

-2

+ _2_ H2O SO2+_4_ H

+1

+ _6_ e-1

40. What is the E0value for the voltaic cell constructed from the half-cells?

(B) 0.426 V

Vol taic cells need to have a positive voltage to be spontaneous. Also, a voltaic cell

must have one thing oxidized, and one thing reduced. Both of the reactions

l isted are reduction reactions. The final equation wil l be:

Zn Zn+2+ 2 e

-1 +0.762 V

Tl+1+ e

-1 Tl -0.336 V

+0.426

41. Which is a consistent set of values for a specific redox reaction carried out under

standard conditions?

(A) E0= +, G0= -, Spontaneous reaction

For a voltaic cell (or galvanic cell) to be spontaneous, the voltage must be positi ve.

According to the equation:

0 0.0592 logcell cell V

E E Qn


17/22

42. During the electrolysis of a dilute solution of sulfuric acid, what substance is produced at

the anode?

(C) oxygen

Electrolysis is a REDOX r eaction. Oxidation takes place at the anode. The sul fur ic

acid wil l not have anything oxidized or r educed. However, the water molecules inthe soluti on act as both the oxidizing agent and reducing agent.

2 H2O O2 + 4 H+1 + 4 e

-1 E

0= - 1.23 V

2 ( 2 H2O + 2 e-1 H2 + 2 OH

-1) E

0= -0.83 V

6 H2O 2 H2 + O2 + 4 OH-1+ 4 H

+1 E

0= -2.06 V

43. Which metal is most reactive?

(D) cesium

Al l of the alkali metals react with water to form hydrogen gas and energy. The

reaction looks something l ike thi s:

Cs (s) + HOH (l) CsOH (aq) + H2(g)

This reaction happens vigorously where the alkal i metal separates the hydrogen f rom

the hydroxide (in the water). The hydroxide remains in solution (making the solution

more basic) and the hydrogen i s converted into a gas.

44. Which element has the largest first ionization energy?

(C) N

I onization energy deals with the energy needed to remove an electron f rom the atom.

The periodic trend states that the ioni zation energy increases from left to r ight

(metals to non-metals) and decreases down the Group (column). Also, metals havelow ionization energymetals want to lose electrons (to become positive), and non-

metals have higher ionization energies (to become more negative.)

Of the elements listed: L i, B, N, & Na, ni trogen has the highest ionization energy.


18/22


19/22

48. What are the elements called for which the 4f subshell is being filled?

(C) lanthanides

Know your per iodic trends and locations on the per iodic table. Group 1A = alkal i

metals, Group 2A = alkal i earth metals, Group 7A = halogens, Group 8A = noble

gases. Know where the s-orbital elements are located. Know where the d-orbital elements (transition metals). Know where the p-orbital elements are

located. Know where the non-metals are on the periodic table. Know where the

metals are located. Know where the lanathanides and actin ides are located.

49. Which ionic compound has the smallest lattice energy?

(A) NaF

The force of attraction between oppositely charged parti cles is directly proportional to

the product of the charges on the two objects (q1and q2) and inversely proportional

to the square of the distance between the objects (r2).

The strength of the bond between the ions of opposite charge in an ionic compound

therefore depends on the charges on the ions and the distance between the centers of

the ions when they pack to form a crystal .

An estimate of the strength of the bonds in an i onic compound can be obtained by

measur ing the lattice energy of the compound, which is the energy given off whenoppositely charged ions in the gas phase come together to form a soli d.

50. Which species have one or more atoms that violate the octet

rule?

(A) I only

Violating the octet rule indicates that the atom is bonding

with more than eight valence electrons. OR, as in this

case, DO NOT have eight electrons TOTAL. Nitrogen monoxide only has eleventotal electrons.

Recall that Carbon, Ni trogen, Oxygen, and F luorine may only have eight valence

electrons. The other bonding non-metals may violate the octet rul e because those

elements are located in the third (or higher) energy levels that include d-orbitals.


20/22

51. In which species is the carbon-nitrogen bond the shortest?(D) CH3CN

Relatively speaking, single

bonds are longer than

double bonds, and double

bonds are longer than tr iple

bonds. Therefore, tr iplebonds have the shor test bond

length.

52. In which species is resonance most useful in explaining the observed bond lengths?

(D) NO2

Resonance structures deal with molecular geometr ies that have multiple possible

structural ar rangements. For thi s to take place, there needs to be one double bond

and mult iple single bonds.

I n (A), NF3has all single bonds (all the same bond lengths). I n (B), NH4+1has all

single bonds (all the same bond lengths). I n (C), NO2+1has only double bonds, and

in (D), NO2-1, there is a single bond and a double bond. Since there are two

different types of bonds (single and double), i t would be possible to explain observed

bond lengths a li ttl e easier.

53. Which description best represents the hybridization of

the C1and C2atoms?

(C) C1= sp3, C2= sp

2

C1has a tetrahedral arrangement (as does C3). C2

has a trigonal planar ar rangement.


21/22

54. Polar molecules include which of those listed?

(D) II and III only

Polar molecules are molecules that are able to dissolve in

water (or other polar compounds). Also, you can

recognize a polar compound i f it has a

lone pair of electrons on the centralatomunless one has a molecule with

sp3d hybridization wi th three lone pairs

of electrons on the centr al atom (l inear

shape). Or i f one has a molecule with

sp3d2hybridization with two lone pairs of

electrons on the centr al atom (square

planar ). Al so, polar molecules are easy

to detect if they have dif ferent external

atoms.

55. Which is an example of an aromatic compound?

(B) benzene

Ar omatic compounds are compounds with a

delocalization of electrons within a ring.

Aromatics have resonance that causes the single

and double bonds to shift See the graphic of

the benzene ring (to the right). This is anorganic structure, and you WI LL become very

famili ar wi th this structure once you are in

organic chemistry.

56. Which can exist as geometric isomers?

(D) 1,2-dichloroethene

I somers have

different

structural

arrangements.
http://upload.wikimedia.org/wikipedia/commons/0/03/Benzene_resonance_structures.png


22/22

57. Which substance is formed when K2Cr2O7is added to C2H5OH in acid solution?

(B) CH3COOH

This is an oxidation / reduction reaction that involves many steps to describe. That is

all you need to write about thi s reaction.

58. Which functional group, present in simple sugars, is responsible for their high solubilityin water?

(A) - OH

The OH group is an alcohol functional group and causes the organic compound

to be POLAR whi ch al lows water to dissolve the substance (water-soluble).

However, theCOOH group is more soluble thanOH whenCOOH is in

carboxylic acid. Carboxyli c acid has TWO polar ends.

59. Which family of compounds is used most frequently as flavoring agents.

(C) esters

Ester is an organic functional group that forms many sweet-smelli ng compounds.

60. In addition to carbon, hydrogen, and oxygen, which element is found in all amino

acids?(B) nitrogen

Amino acids are proteins, you wil l not need to know the formulas for amino acids,

but you wil l want to know that amino acids are hydrocarbons with ni trogen.

Documents

2006_explanations.pdf