7

Ghem 167 tl:Exam 3 ReviewSupplemental lnstructionlowa State University

Leadcr: Emily andManCourse: Chem 167

Instructor: BurnettandBonaccorsiDate: Nov l7l18

l. Draw lewis structures for,&e following molecules. Give the shape of the molecule,hybridization of the central atom, pola,rity, and the bond angle(s).

a. CHzFz ? ".4 _c_F:

Iil:(:b. OFz .. r.o''.(' " \(".

a tt ,.

'lrig**nt pqmn,det ;st3 ; <tm.5,; ptrr

trigonil flun*r ; $11 I lL00 j ttortpoter

lirremi st; tBoo ; r,loq)ofer

tdrnhredrol ; \t3; l$q,n, ;FtLr

burt , Spt ,,< 10Q,50,, |olUc

-

)

Element H C N oElectronesativitv 2.1 2.5 3.0 3,.5

0,q0,qI,t\. 0u.5

a. C-Hb. N-H

@ o-Hd. o-ce. O-N

t060Hixson-LiedstudcntSuccEssc€nterAsfiAg4-ffi2/-*sistaff@astate.edu+htp:i/www.si.iastate.edu

/

\..,,\

o) l0 d)@c) \J

a. o, spr T[, pb. 6, sp2, rE, sfc. o, sp3,7t, s

@ o, sp2, zr, pg. 7[, sp" o, p

5.

6.

8.

9.

L.Sb. A1c. Ga

a.b.c.d.e.f.

cII4 Londlfl disps/'sion9Y:oH H- bond,r,g

5l#ili?,l li:Fr$,nBBict

-,t1- boflot[J0ipoie -dipore

Which drawing represents a n boading molecular orbital for a homonuclear diatomicmolecule?

f'.f'' Ot)a4. In ethylene (H2C{H2), the C:C double bond results from 6 overlao of SDI

orbitals and T overlap of D orbitals on the C atoms.- ---r*-

Nickel crystallizes in a face-centered cubic lattice.If the density ofthe metal is 8.908elcttf ,what is the unit cell edge length in cm? FCr: { UhmSST.bqla \ y " lgd-- * 4ahrrts = 3,lqWt|-LZg . \-- ry

\ fno I (0, Ottr i06afoo: Uni't- Cetl 8,900q j,B4Qt,^-Which of the following statements aboutthe allotropes of carbon is falsg? - CilrV

-' ,', ''3a. In diamond, the carbon atoms are bonded together in a three-dimensional v- srL

tetrahedral lattice. - _ vl ,j77xta-rs ,

D ffit*tr"*lar properties to diamond because they are both made of only =F6ffc. Diamond is very hard and inert because of strong covalent bonds holding all the

atoms together. vd. In gmphite, carbon atoms are bonded together in trvo-dimensional planes.e. Graphite is soft because only weak forces hold the planes of C atoms together-

7. Which of the following would be a p-type doping for As?

@ (b) and (c)e. (a) and O)

The atmosphere around the earth is warmed because9, Warm air cannot escape, as in a greenhouse

Cb) tr,tol.rules in the atnosphere are-warmed by radiation from the earttr that retain\-/ .heat

c. Fossil fuels release heatd. Plants absorb COze. Plants release COz

For the following molecules, determine what Intermolecular forces are present and rankthem in order of increasing strength

UHrl e qrltru c BBfCU= t Hso t1"CH, NHyo hro

7\-/

10. Regarding trumber 9, which compound would have i

a. The,highestboilingpoint Hf_Ob. The lowest vapor pressure q20c. The lowest melting point ,fi;

11. Which of the following polymers is an example of a block copolymera. ABABBBABBABBABb. ABABABABABABA

,d) a,q"qnBB&MBBBY EABABABABABABAe. None of the above

12. Using the thennodynamic data, deterrrine if the following reaction is spontaneous at onlyhigh or only low temperatures? (AS NO=210.7Jlmol*K, Nz=191.5 Jlmol*K, Oz:205.0J/mol*K) aR+- i'^lln,pl,shl Sprrf".@ h,aaT, Nz(s)+o2(g)+ 1s0.5 kr + 2No(s) - ; il};gu,rr" a ^:, ,, .r

L(t- 2-lb,yr-/rnor -1- ft^ rQt.Ftlmor.ir)+ {rxr-or.o {nrur b1= Ll,g4w13. A 0.500 g sample of naphthalene (Crotla) is burned in a bomb calorimeter containing 650

grams of water at an initial temperature of 20.00'C. Afterthe reaction, the finaltemperature of the water is 26.4oC. The heat capaoity of the calorimeter is 420 J/'C.Using these dat4 calculate the heat of combustion of naphthalene in kJ/mol.

y:" {r,? {5,,':y qofr { ao, q o c - 20'$] - ( rr ro q,il (,rr,,q,c _ Lo.)]

{sorr= 20 .o'l'l W+W*I ffi =l-a,YJ,t u.r/no!

grams of water at25.A "C. The specific heat of aluminum is 0.901 Jig oC. (Coffee cupcalorimeter problem.) - qftt -_ a_!W

l-

- /(to q) ( o ,Qftr r/no\{+^ ,en,\fLtu t) ( 0 ,q0 | tlq'){Jp- t30,c1 = [roog)(q ,r$ {/g,c) Vt _15,ilE?Zd7D t

15. Find the AHo,,, for CzHo(g) + 7D Oz(s) i 2 COz(g) + 3 HzO(e)

AH"rCz[IoG) = -84.2 kl/molAH"1CO2(B) = -393.S kJ/molAH"1 H2O( g) : -24t.8 kJ/mol

16. Withoutdoing a the entropychange will be positive ornegative when each ofthe following.reactions ocflrs inthe direction it is unitten

a. c&oH(t) *f,orb) - cor(s) * ZH2o(sl + A\b. Brz(t) * Hzb) - zV*rts) + A$

Krr'sqr J,?r!,\, I#y?q|w nufl - ft y *bq n wno\ n(t x 0 o,tffiq

17. Which of the following statements aboutenergy is true?a. The change in energy of the system + the change in energy of the surroundings

for an exothermic reaction is negative ^fuqt = fsunr.A substance that soes from a solid to a sas has a positiv,for an exothermic reaction is negative ^Sqt = ts:.tr Sug+ffn dA substance that goes from a solid to a gas has a positive work tenn. ",[[;iil ;The enthalnv for a reaction in a bomb calorimeter is eoual to the chans6in heatths enthalnv for a reaction in a bomb calorimeter is equal to the changdin(q). AH= tl = l6+p5u Lo{4.ee* 6' u}

@ The most efficient electricity conversion is elecEical)thermal. lAhVq,l

ft\so s fP pnds

22. Given the following reactiors,

2 S(s) + 3 Oz G) ) 2 SOrG) AH = -790 kJS(s) + oz(s) ) Soz (s) AH: -297 kI ltiX; r 2_

Whatis AHo forthereaction2 SOzG) + Oz(g) + Z SO:(g)?

.}}s +wL(5\+ ,- sogi$ aH - -'tQo u-r':}S"'*Ztkf, + Lafiq\ bA, 5q4 wa'q;ffiXs[i,a]ea,s@

23. Write the forminUu$\ * C6*1 + 3/firlr) *) Co,Lo3{r\

24. Silane, SiI{4, hnos according to the reaction, Slf-I4 + 2 Oa * SiO2 + 2 HzO, withAHo : -1429 kJ. How much erergy is.released if 15.7 g of silane is bur-ned?

15,?gSiHqllvnol ., lmol rrnga_,n-g u

\rnui$E x

\$r!nqahw-\Jb.

c.

18. The total number of o bonds in the H-C:C-C=C-C:C-C:N molecule isa.4b.5@*d. t2e. 15

19. Which of the fotlowing molecular species is stabilized by resonance?a- COz@I:: NJ*N-trl ftl*f{?Nc. BHI lv r\ rw 'E

d. Or'' n t- nl - nle' HCN N=ttl'hl : '

20. What is the coordination number for (a) simple cubic (b) body-centered cubic (c) face-

SL: bBut = g

rcL- tL

2I .lf 3 .4 kJ of heat flows out of the system while 4.8 kJ of work is done by the system on thesurroundings, what is the internal energy?

f*fftt)= k 5,1 4rf.i,ru1 = -$.t w

AH'/rool rxn

liml rxn

25. How much heat must be removed to change 75.0 grams of water at25.A "C to ice at -35.0oC? A1I"665. ice : 333.5 5 ilS; specific heat of ice = 2.03 Ilg"C

26. Consider 10.0 g of water placed in a freezer at -15oC. What is the entopy"chem;srrounding when the wder freezes? For water AHnsion=338J/g.

kt "ffitlr= (lbd[.r. ru "/6,il(0,r.

_ t_b.N: _ J. Bq LrR'"CI=

rn x Lupus\; = ttr$1ro,i3i62 ) ri,';r7o@ brnr^r=.

-S,iu gi.r;.,r,A l,;Z!r- o.a = lWi'q@

At-- yT {rqs= ' 33Y x /0 g t11i -- 4,380 t

3AS=tff=@1L58 V

U