Strong/ Weak Acids and BasesNeed To Know:

Which acids are SA? (top 6 on table)Which bases are SB? (bottom 2 on table, AND metal hydroxides)Levelling Effect:

o the strongest acid that can exist in solution is H30+o the strongest base that can exist in solution is OH-

For SA and SB: ionize 100%For WA (we find K, on table)For WB (we calc K, = Kwl Ka)WA - WB equilibria

o Writing Ka, x, expressionso Determining which reactant acts as an acid! base (look on table)o If reactant is amphiprotic (compare K, to Kb)o Conjugate acid-base pairs: predicting (acid 7 add H+), (base 7lose H+)o Determining which side of an equilibrium system will be favoured (compare

acids: the stronger acid is more successful in donating H+); the other side (withweaker acid) is favoured).

Effect of temp on Ka of water:o Ionization of water is ENDOTHERMIC (H20 + heat ~ H+ + OH-)

Questions:7. What is the concentration of [H30+] in a 0.0035 M solution ofHN0S A

H-~03l~) -+- H20)~ H3D~\ of NO~-( .l. t c.t.i> tCub )

0.0035 K 0.0036 tv\

[t-\ot>+] ~ o. OO~S fv\

8. What is the concentration of [OK] in a 0.0020 M solution of LiOH? sBL, OHLCU\) ~ L,-\- ·-+0)-\·'- ~0.0020 M 0,00 20 M

CaH-] ~ O.(lY20 t-'\9. Four acids are analyzed and their Ka values are determined. Which ofthe following

values represents the weakest acid?A. Ka=2.2 xW·•••B.' U = 6.2 X 10-9

"f E'a- 1 7 X 10.12 .<i~ ~;1.2 x 10-9\ Ctrjlr \\~ .. , strO(\S.t~

Jna\\~(' ho. '.' Weu\{1('·

10. What is the conjugate base of: _a. HCN eNb. HF E-----c. H3P04 f-b Rbl\-,

Which of the above bases is weakest?

11. Which of the following Kb values represents the base with the strongest conjugate acid?

~ Kb"".4.2~ . . .•.: K» =9.5.x.. Hr: \\\ tC\ \~{( b 0.5 Q. 0 •• s.+rontJ\-l ( CDn\·

C. K.b= 2.0 x 10'') V Jb. Kb=7.8xHr! (SmaHl,st Kv) ( \()~r Ka.)

12. HS-reacts as a base when mixed with water.a. Write the reaction ofHS- with water:

w- """'"

}-ts- -+ H1-D ~o.CLep~ H t

b. What is the Kj, for HS-?

KvJ¥;?X

"- (J)y\, au d J Hi..~

13. Which substance acts as the Bronsted- Lowry base in the following reaction?~.T

02- + HSO --7 OR- + SO 2-.44'2.- . b 0..... CL bo Q,cJs. as !be 'oa~

14. Write the equation for the reaction that occurs when oxalic acid, H2CZ04 is added towater: .. ------~ II ..+

('Mf.\ ') H2C.O~(~ rhOll)~ I-\c'2.0't-;'~) 1- m,O l~)

15. Write the equation for the reaction that occurs when the amide ion, NHz-is added towater: ~ _

Nt-\; -+ HLD --7 N \-\3 uq) -t 0 H lO1--). ltl{.> U\

CSt»

Amrh (ot~'wroh ~ft

wit-~

16. Write.the equation ~~eaet~hat occurs when oxalic acid, Cr(H20)l+ is added to 2.- +water. C(' L H~O)6~-t + HI.O( ) .~ H0o -+ + Cr (rh- 0)5 (0 H) .

'D- (~) b I '~ (to}.) b (CVf )

17. Write the e llatio for the reaction that occurs when cyanide ion, CN- is added to water:

20.

','1h~~j~~ b~{1flIASOl~h.~~g:~~.y H~4s0~,D~ H2AStl.-"

21. In the following equilibrium, predict whether reactants or products are favoured., \a) CH3COOH + HS- ~ CH3COO- + H2S

'0.- '0 '0 ~CLL ,

COO\>Q(e CAcA &~ > c~seaOH- \~ s h-oY\~( _than 14-L~b) When HeN and NH, are mixed. D-p-ro-d-U.-C-r.-~-·-a-(~e..---"f6-':-~-\J-OU-{et-f]

1~' i'nCN -T ·J~-J\-\3(uq...) ~ N~LL +C-N-ca.\-) '1

~ b 0.. bL l-- ~\ \

Compa(~ O(id~" t'-l~Lf-"t IS 6'-hnnj-!( -than H-eN1E0tC+~~Me. fC--\" O\A (~

22. Since the ionization of water is endothermic, which of the following is true at 12°C?L -e-rL__ $hl({S Grt -

. J(w=,~ L Hl. 0 .-T h-eCl-l ¢ \-\c>CJ~ + 6H-Kb ( \) \ ( tuyl ( CUi-)

Kw=- d« ~Ka f(i'Y1P

Kw:> 1.0 x 10-14c_Kw ~ Cr\~D~[OH-J

\ess +h~n \ ,0 "ID-1'i,---.- ..~Kw e LS-~ c.23. The ionization of water is given by the equation below:

~2HzO + heat ~ H30+ + OR"

fa) If water is heated to 50°C, how do the [H30+] and [OH-] change?

C\-\-ot>-tj (A(\<1 rO\-\:J \f\l( «is e. , et}-UCA\t1 .The- C J\ S 91{ iC\.\.-i ( th 00 \' O~lo-t M

b) Is the water still neutral? Explain.

'I ~S. ,A·~ tSo ~G) 'LH3D-t]::· C O)1j

So wakr \S Sfdl Y\-(L,d-YQ I·Kw h.as. \' f'-C( ~CtS~J » h()WeV0,

Need To Know: - pi+• pH = -log [H30+] [H30+] = antilog (-pH) 0:::: \ 0• pKw=pH+pOH=14• The pH scale:

o 14

C,~ o(:cid) \., \ -1. \ -s IH30't] chariges b~ 1Oxw~'theac~ P.Hle~el ~,,: -'1-"~~se) I -N

\~~:.J'::. \0 \0 \0 \0 10''1 \0-5 \0-<' \0-1 IO"'t 10-" io" 10 I() 10 I!> 0• Finding the pH of SA/ pOH o[SB: recall [SA] ~ [H30+], [SB] ~ [OH']

(lo\J~h ,'on;"lfod)

Questions: S+rc~ Ac.;tll tL"fb )r---/'--'"

24. What is the pH and the [H30+] 0[0.256 M HCI04 in water.

}+C\04, + 1-\2_0O. ~5~ V\

C H~a-Q'=: 0, 2-'Sh f.A

'-7 HoQ-t + ClO~-0, }sfc, M

P 1-\ = - h~JLO\'2Sb)=- 0,59 'L

25. What is the pOH of an unknown solution that has a [H30+] = 5.2 X 10-9 M. Is thissolution acidic, neutral or basic?

C\-\-oD-tj -:::-5, 2- v-: \ a-c, K

TI Xl'.)iL 1 p 1-1 ~ - \ \) 8( 'S, 2- "- \0-"I) = 5 ..Z. {3po H- = \ t-\- - '8 \ 2-~ ~ S-.. '1-- L

26. A solution has a pH of9.35.a. What is the [H30+]?

Cr-h,<)"TJ= IO~q'~I~ ? ant-l/~tPH)CH?>()+] ~ tt,5 X \D M

as [H~oj \(\l(e!:IV£ J "}h.e p t-+ d-ecreos..eS.(1.(\6- +h~ ~rt \(\L( ill S e ~ ,

b ~OH- -=- \Lt - P++

Titrations

Need To Know:• Titration calculations: need to write reaction equation between acid-base• Find mole ratio!

o mol std ~ mol sample ~ [sample]• If given data for trials ...discard vol that differs by > 0.02 mL

Questions:28. A 0.200 M solution ofNaOH is used to titrate three separate 10.0 mL samples ofHBr.

The data is shown below:

VolumeofNaOHus~ .T~al1:~mL' cLi rk-r~by '/0.02 tt.LTna12: 10.01 mL 7 k~ '-l-l!.rtv).{'"Trial 2: 10.02 mL ~ "Gt()~

IJIIDrscard

i. What is the average volume ofNaOH added for the titration?

CA\),~IJ O\·~ \ 0 . 0) n\ L + \O· 02. rnL-2-

- /0,016 mL

~ )/0.01 mt--.}round ed up·

11. What is the [HBr] originally present in the samples?

mo\es N ClOH:=- p ..LOO m~l 'A o.OIOO?-.)(_.,.:~'

U-rn-OltJ-S-Of--.r-N-o-O-H ---O-~0-02-,L-, O-)()-4--m-o-)] ~- ~ _

/0.02 mL =. O. a/UOL L-

G) Fi(\rJ molDs 0{ H5r J n So. rrple ~

Na 0 J-/+ H 5r ---7 1-/2- 0 + Nu 8,/ : J

0.002(04 mol ,~ O.(>Oluo"-l mol·

([) F;'() d LJ-f brJ ".I

Conc'~ mo\\)0 I

LH'bvJ =-, 0·,C0200Y mol H5. "10,0 axL