Exam 3AC h e m 1 1 4 2Spring 2019N a m e :

Multiple Choice. [2 pes ea.] Record the best response on the scantron sheet. [40 pt.s total.]

Assume nil solutions are aqueous and at a temperature of 25 "C, unless stated otherivise.

Ql. Bases turn litmus what color?red

B ) g r e e n * ^C ) r e d b l ^D) yellow

Q2. The Arrhenius definition of an acid is:A) they donate H"" ions to other molecules

they t"orm ions in water ^C) they accept electron pairsD) they turn litmus red

Q3. A good example of an Arrhenius base is:A ) n h 3 i r

<52EOHZDC) CH3CO2HD) HCOj- L ' o n

Oh' l'»A -So 1

Q4. The conjugate acid to HPO,"' is:A)H£0^^C) P0.5-D) H30^

l t > a . C t d

Q5. An example of a strong acid would be:

Shno.rCTH^soTO HC<04

D ) H j P O . K M a , H r

Si'K <*.ci(IU ■HiSo,,HC<Oi,HMO J

Q6. At 37 °C, A'w is equal to 5.5 x 10"'" . This means the pH of pure water at this temperature will be:A) 7.00

ICo' CK^3COH'B) 5.50CL13^

CP)6!63"^

PK - <c>'hl

^ HV«£\ \ ,

- 1 - ^ = ) > y ^ j 6 - $ r d O

Q7. Which of the following diagrams represents a snapshot of a very small portion of a beaker containing a weakacid, HA, dissolved in water? Note that the solvent molecules (H2O) are not shown for clarity.

= HA molecule ^^=H30+ion 0=A-ionCfcfs

OS c ?c ? CfaQ o >

(a)

Q 00

Q

Q G

(c)

ooo

auAf

A ®

Ik"Q8. Given three separate solutions containing equal concentrations of formic acid (ATi = 1.7 x lO"*), phenol

. (Ki— 1.3 X 10"' ), and acetic acid = 1.8x 10" ), select the response below that has the acids arranged inorder of mcre iiwg-percent dissociation at equilibrium.A) formic < phenol < aceticB) formic < acetic < phenolC) acetic < formic < phenol

^ phenol < acetic < formic^^

c{OJA cl

Q9. If the concentration of hydroxide ion is 1.8 x 10~* M in an aqueous solution at 25 °C, what is the pH of thesolution? pOn= -locCofl-J:A ) 2 7 4 • ^B ) 3 . 7 4 ( P 0 H : \ 0 . - o o ^ 1 - o oC ) 9 . 2 6 » J O , 2 ^ ( 0

CP) 10.26j>QIO. Which solution has the largest pOH at 25''C: 0.100 M NaOH(aq), 0.100 M Sr(OH)2(aq), or

p H i - l o t £ o . » o o ^ 0 . 1 0 0 M H C l ( a q ) ? ^ ' L ^ 8 " J .A ) O . l O O M N a O H ( a q ) j 1 . — + PB ) 0 . 1 0 0 M S r ( O H ) 2 ( a q ) ^ \ p K — * 1tfTnTlOO M HCl(aq)" VqOH S. -lo^ fO-loo' 5 t

= I »oo &

D) Impo,ssible to determine -F- 0 0 0 p O K \(JU pH - o^r\jQll. What is the pH of0.25 M LiOH(aq)> f> -lo fO'&ooN

A ) 0 . 6 0 T j o . b ^ \ l S f f o H V - ^ S f ' - ^ - ^ l O nL,-OH"U\OH'

Q12 . A Lew i s base i s a (n ) : tU -OO - ?A) electron-pair donor_^B) proton acceptorC) electron-pair acceptorD) proton donor

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Q13. Which pair of substances will constitute a buffer when found in solution together:A) NaNOz / HNO3B ) K C 1 / H F o c F J , t A * - /.21O h f / N ^ D , , r _ r k l - ^ x : - ^D ) N a N O i / K N O i ^

Ql4. A solution containing 0.30 M HClO(aq) {K^ = 3.5 x 10 and 0.25 M ofNaClO(aq) would have apH of:A ) 7 . 4 6 t u c * t ^ f

CrB)7.38 3C ) 7 , 5 4 . ^ l - H hD ) 7 . 3 1 K - h < a ' - ^ > 7 - 3 8

Q15. A weak monoprotic acid (HA) has apA"., of 3.94. If we need to prepare a buffer with a pH of 3.74, then we can

fw Cfb.! J-. »■< >c;>0B ) [ H A l = [ A - ] - 0 . 2 0 M . b / . . I r t r . { ^ /C ) [HA]< [A- ] o r - ^ | ,p \ -p )C^ . -0 -10= (05 4D)[HA] = [A-] + 0.20M r 0 - b 3

Q16. Which of the following acids would it be best to use to prepare a buffer with a pH of 4.25?A)HC102.A'.= 1.1 X 10-^ pt, =B ) H N O 7 . A : , = 4 . 0 x 1 0 - ' V ^ O 1 . f ^ I i T f t / L l

f ^ T T H C H z O . A : , = 1 . 8 X 1 0 ^ - a 3 .■? ^ ^ WD)H,C03,3:. = 4.3x 10-^ , fc-3T /'W" b-fto a wW pfe*XpH \ QO >t;bj f

t V 4 « A C ^ O /Q17. Which chemical equation best corresponds to the A',p reaction for calcium carbonate?

A) CaC03(s) ^ Ca^(aq) + C^^(aq) + 20^-(g) uB ) C a C O s C s ) ^ C a ( a q ) + C 0 3 ( a q ) I ^ \ ^C) CaC03(s) Ca^(aq) + CO^-faq) 5bW ^

( ) CaC03(s) Ca (aq) + C03--{aQ18. Which substance will have the smallest molar solubjlkv: BaSO.. f A'.p — 1.07 x 10'"'),

CaSO,{A',p = 7.10x 10"'), o^eS (/Tsp = 3.72 x l^^T^ , P j \ fl ^A ) B a S 0 4 ^ I G p v l ' , ^ U J o W 6 V S W lB ) C a S O i l o i A * ^ W A o l c J 5 f t '

D) Impossible to determineQI9. In which solution would ammonium fluoride be the most soluble?

c ) a 5 0 M i j | ( p ) } p - > y < ^Q20. The solubility product constant for magnesium hydroxide, Mg(0H)2 is 2.06 X 10"''. Which solution would /

^m a prec ip i ta te immedia te ly upon mix ing? , x ^solution containing 1.0 X 10'^ M Mg^^ and 1.0 X 10'^ AI OH' 5 '

B) A solution containing 1.0 X 10'^ M and 1.0 X 10"* M OH'C) A solution containing 1.0 X 10' Ai Alg^ and 1.0 X 10' M OH" Cl> ~ D) A solution containing 1.0 x 10' M Mg " and 1.0 x 10'*^ M OH' '

I f ' J C i s p > K s p / o t H SQ>P^ 60 yio- ) = (O' >2.-ob.fo'\r J ' ) • '

J . f p l - w p ^ K i p . iQ>p

Short Response.Show ALL work to receive credit.

Q21. [15 pts.] (a) The pH of 0.13 M HF(aq) is 2.01. Use this information to determine Ki for HF. Be sure to writean ICE chart as part of your answer.

Fc6g) ^F'co^O M 0 0

- X - F X

O - K l -I W fl- p H - z - o i- " X - ^0"' °' r 7-^y(o"^

- i ' O i

(b) Using your calculated A' , predict the pH of 1.3 M HF(aq).

4 H i C X t N - V

J - | . S , X O Oc - * ^

£ ( X )- "X^ n T-'icIo"'*'. ksS^Mx X<c{ l

r S X , i S1 - i

$ 7 . ^ ^ 7 . 1 < . 0 - - = 2 - 5 7 .' l k a : I .

(c) What is the percent dissociation of HF in part (a) vs. part (b)?

P a r t ( a ) % P a r t ( b ) ^ %

= 0 X '^ O . o 3 > 2 .

H=-IOLHOr

% j j o c . = ylOO > (00 - "? '3o.\S

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Q22. [15 pts.] (Be sure to write all relevant chemical equations and ICE/ICF charts for this question.)250.0 mL of0.400 M HN02(aq), Kx = 4.0 x 10 is mixed with 50.0 mL of 0.800 M NaOH(aq).

(a) Calculate the pH of the solution formed.

, ( L o . U o O A i . » \ r * ' i -2 ^ 0 . O i u L ; c * — •l O O O ^ L . I L -

—r 7^ \L e>-8oo«.l UOH . o.o<+oo«.i^ 0 — ^

pl= - -( f

(OOD«MU u

X " o . t o o O . O H O O

C -O-OUOO -O'O<*00F " O . O b O ®

o

4 O >0(400

o ' 0 < - k O O C i M iic<ii oJh

' I-VL•OHooiu* (oO -Cfeo «*ol /0®o

fXM

(b) If 0.010 mol HCl is added to&

the so lu t ion fo rmed in

r 0 > 0 1 0 M O \ ^ . O H O O 0 > 0 b O

c > o t o - 0 . 0 ^ 0 . O i O

P 0 0 > 0 ^ ^ 0 . o 7 C i

jW ^ ■ * *CbcMtD . 3 . i + « i 1^ c

c ? » o j o

o . o " ? ©^ . o 3

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Q23. [15 pes.] Calculate the molar solubility of aluminum hydroxide in pure water vs. in 0.200 M KOH(aq).Comment on the difference, /fs,, for Al(OH):\ is 2.3 x 10

Be sure to write the AT^p chemical equation and an ICE chart as part of your answer! Explainany assumptions you arc making.

A/ ( ^ 3 (s^

r

c

I (hssolo! IAc \ O l " !

■■-s"o

+ s

CA

[pH-J

-■ ) f s X ^ s f -=■ ) S =

o

4 i : s

(}sCo>^

Alfoii\W ^ AiOH C<1^\■ J - Q O - 2 . 0 0

^ + s

^ ( s ) ( o - L o o i 2 > s )

2-STIO'®- (i)(o-Loo-y:h'\ X s (o•2Do

. LOO

- 7 5 =

(O'lOO ^

I TH£ fc'ffoRr g? AVoiO 'CUC-Sf&AK' ("(SNMiAAJui"5ee "/(JtA -ftoA (?utm t h i U t u f f . . . L U o r - / L ift vi/itK 50i^e otiyr of M&W- SC>\ • fVAUC^ \Ow^r Ui\ ^ P ' * ^ ' t d < ' 0 ^ » \ A — ' "

f ' # ' i ■^ p ', ^ C U i . U f ,

3 , - - .^ J 2 U ^ c ( ( i i o ( u c /

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Q24. [15 pes.] (a) Write out the chemical equation (reaction) corresponding to ATi, for CH3CH2NH2(aq),ethylaminc.

(b) Write out the chemical equation (reaction) corresponding to /f,

2 . H 2 , 0 ( J l ^ ^ f « £ ) .K , p a ^ K'C«£} -<r C>K~fQ

(c) Without performing a calculation, explain how the pH of 0.100 M NH3(aq) compares with0.100 MLiOH(aq).

^ , ' 0 H A^ bciA^ a- X<3[W< (Cv\C

(d) Calculate the pH of 12.0 M HCl(aq)(concentrated hydrochloric acid).

H a - - V a '

6 < - A H Q ( V ^ ^ - ^ C W c a ^ )a - o i ^ a - o M

tH^3= -K L\2..o3 --

Bonus questionPredict whether the following aqueous salts will be acidic, basic, neutral, or whether there is not enoughinformation to decide.

NaF baj[\c AlfNOO. aoiji'c UC1_A£A)

N ^ O n ^ ^ ^ "

1 / I n f o r m a t i o n

l A M A P e r i o d i c Ta b l e o f t h e E l e m e n t s M I A I V A V A V I A V I I A V I I I A

1

H

2

H eI . O U 1 3 1 4 1 5 7 6 1 / 4 . 0 0 3

3 4 5 6 7 8 9 1 0

L i B e B 0 N 0 F N e6 3 4 1 9 0 1 2 10.61 1 2 0 1 14 01 16 00 1 9 0 0 2 0 . 1 6

1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8

N a Mg A ! S I P s 0 1 A r22 99 2 4 . 3 1 1 0 1 1 1 2 2 6 . 9 3 2 8 0 9 30 97 32 07 3 5 4 5 3 9 9 5

1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 5

K C a S c T i V O r M n F e C o N ! C u Z n G a G e A s S e B r K r3 9 . 1 0 4 0 . 0 8 4 4 9 6 4 7 . 8 7 5 0 . 9 4 5 2 . 0 0 5 4 . 9 4 5 5 . 8 5 5 8 . 9 3 58 69 83 55 8 5 . 3 9 6 9 . 7 2 7 2 6 1 7 4 9 2 1 6 0 7 8 . 9 6 79 90 8 3 8 0

3 7 3 8 3 9 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 5 0 S I 5 2 S 3 5 4

R b S r Y 2 r N b M o T c R u R h P d A g C d I n S n S b T e 1 X e8 5 . 4 7 8 7 . 6 2 8 8 9 1 9 1 . 2 2 92 .91 9 5 . 9 4 1981 101.1 1 0 2 . 9 1 0 8 . 4 107 .9 11 2 . 4 1 1 4 . 6 1 1 8 . 7 1 2 1 . 8 1 2 7 6 0 1 2 6 9 1 3 1 . 3

5 5 5 6 7 1 7 2 7 3 7 4 7 5 7 8 7 7 7 8 7 9 8 0 8 1 8 2 8 3 6 4 8 5 8 6

C s B a ' L u H f T a w R e O s l r F t A u H g T I P b B l P o A t R n1 3 2 . 9 1 3 7 3 1 7 5 0 178 5 180 9 1 8 3 8 1 8 6 . 2 1 9 0 . 2 1 9 2 . 2 195 1 197 .0 2 0 0 . 6 2 0 4 4 2 0 7 . 2 2 0 9 0 12101 i 2 i o : 1777]

8 7 8 8 1 0 3 1 0 4 1 0 5 1 0 6 1 0 7 1 0 8 1 0 9 n o 111 11 2 11 3 11 4 1 1 5 l i e 11 7 11 8

F r R a " L r R f D b S fl B h H s M t17711 1226) 12621 1 7 6 11 17671 17661 17641 17651 17681 12591 1272! 12771 [ 7 8 5 1 1289! 12931

5 7 5 8 5 9 5 0 6 1 6 2 6 3 5 5 6 6 6 7 6 8 6 9 7 0

L a C e P r N d P m S m E u G d T b Dy H o E r T m Y b1 3 8 9 140 1 140 9 144 2 11451 1 5 0 . 4 1 5 2 0 157 3 1 5 8 9 1 6 2 5 0 1 6 4 9 1 8 7 . 3 1 6 8 9 1 7 3 0

6 9 9 0 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 1 0 0 1 0 1 1 0 2

A c T h P a u Np P u A m C m B k C f E s F m M d N o12271 2 3 2 . 0 231 0 236 0 17371 1 2 - U l [7.131 (-•471 [7171 17511 1257! 17571 1756: 17531

7Va = 6.022x10" mol"'

« = 8.3145— 0.08206""^'^ M,V,=M,V,m o l - K m o l - K

pH = -log,o[H"] pH + pOH = 14.00 (25 "C)

^ 1.0 X 10-'- (25 "C) K,-K^=K^

pH = pA: + logiB a s e

A c i d

Given: axr + bx-'t c=Q, then X = -h±^Ib^ - 4flc+ Ht.OONa AAo,-^Q,

l a

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