General Chemistry 2 Final Exam Fall, 2013 (1/2)

감독자인
계열/학부/학과: 학번: 고유번호: 성명:
수업요일 및 담당교수명: ( , )요일 ( )교수 자필서명:

H He <주의 사항>
Li Be B C N O F Ne 1. 답은 지정된 자리에 반드시 영문(English)으로 기입할 것.
Na Mg Al Si P S Cl Ar 2. 시험 시간은 60분임. 400점 만점 (full score = 400 pt).
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 3. 문제지는 1장(2면)임. 연습지 및 영한사전 사용 불가.
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 4. 7-12번은 풀이과정을 반드시 밝힐 것.
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 5. 계산기 사용 무방하나 빌려 쓰지는 못함.
Fr Ra Ac

1. Write T for true statement or F for false statement in ( ). ( B ) Which of the aqueous solutions below has the lowest pH?
-5 -5
[6 pt for right answer, -2 pt for wrong, and 0 pt for no answer] (Ka for CH3COOH = 1.8 x 10 , Kb for NH3 = 1.8 x 10 )
[ T ] Esters, amides, acyl halides are carboxylic acid derivatives. (A) 0.001 M of HCl, (B) 1 M of CH3COOH (C) 1 M of NH4Br
(D) 0.1 M CH3COOH/0.1 M NaCH3COO solution (E) pH = 3.5
[ T ] Anode is positive in electrolytic cells and negative in
voltaic cells.
[ T ] A solution is basic if it contains equal amounts of HNO3 ( C ) Consider solutions of the five indicated salts dissolved in
and Ca(OH)2. water. Which one could not possibly have the pH designated?
[ F ] A peptide bond is formed as a result of a redox reaction Salt solution pH
between two amino acids.
(A) NaCl 7.00
[ F ] The pH at the end point in a titration is always higher
than the pH at the equivalence point. (B) NaF 8.16
[ F ] Cycloalkanes can have cis- and trans- isomers. (C) NH 4Cl 7.64
[ T ] The coordination number of a complex may be larger than (D) KCN 9.48
the number of ligands coordinated to the metal atom or (E) NH4NO3 5.90
ion.
[ F ] Methyl orange (color changes at pH = 3~4) is a good ( B ) If X = the molar solubility (mol L–1) of Ni(OH)2, which of
indicator for the titration of 0.001 M HCl with NaOH.
the following represents the correct relationship between the Ksp
[ T ] The solubility product (Ksp) of calcium dihydrogen
2+
phosphate (Ca(H2PO4)2) is expressed as [Ca ][H2PO4 ] . – 2 and X, the molar solubility of Ni(OH)2?
2 3 2
[ F ] When two different compounds have the same solubility (A) Ksp=4X 3
(B) Ksp=4X
2
(C) Ksp=2X
product values, their molar solubility is the same. (D) Ksp=X (E) Ksp=X
[ T ] Strong field ligands cause large crystal field splitting and
low spin complexes. ( C ) Which of the following salts is more soluble in acidic
[ T ] The general formula of cycloalkyne is CnH2n--4. solution than in pure water?
(A) AgBr (B) Hg2I2 (C) CaF2 (D) PbCl2 (E) BaSO4
2. Choose the best answer for each question. [12 pt ea]
( D ) Which of the following titrations could the following curve
( D ) Which one of the following compounds has optical describe?
isomerism? (A) KOH added to HNO3
(A) CH3CH2OH (B) CH3CH(CH3)OH (C) CH3C(CH3)2OH (B) HCl added to aqueous NH3
(D) CH3CH2CH(CH3)OH (E) CH3CH2CH(CH2CH3)OH (C) HNO3 added to KOH
pH
7
(D) NaOH added to CH3COOH
( E ) Which one of the followings is not a biopolymer? (E) CH3COOH added to aqueous KOH 0
(A) deoxyribose nucleic acid (B) protein (C) polysaccharide Volume Added

(D) rebose nucleic acid (E) polyamide ( D ) What kinds of isomerism do the two pairs of complexes in
the following list represent?
( E ) Which one of the following is not oxidation reaction? (a) [Co(NH3)4(OH2)Cl]Cl2 and [Co(NH3)4Cl2]Cl․H2O
(A) combustion of gasoline (B) CH3CH(OH)CH3 → CH3COCH3 (b) A
A
(C) CH3CH2OH → CH3COOH (D) CH2CH2 → CH2(OH)CH2(OH)
(E) CH3COOCH3 → CH3CH2OH D
M M
D (M = metal; A, B, C
B B
C C and D = ligands)
( B ) Which one of the following combinations cannot make a
buffer solution? (A) a: linkage, b: optical (B) a: hydrate, b: linkage
(A) NH3 / (NH4)2SO4 (B) HBr / KBr (C) HCN / NaCN (C) a: coordination, b: linkage (D) a: hydrate, b: optical
(D) NH3 / NH4Br (E) HF / NaF (E) a: ionization, b: optical

1 2 3 4 5 6 7 8 9 10-a, b 10-c 11 12 Total

72 120 24 30 14 14 15 30 15 6 25 15 20 400
 General Chemistry 2 Final Exam Fall, 2013 (2/2)
3. Write the products formed at the two electrodes in the 9. Calculate the pH of a saturated magnesium hydroxide solution at
−11
electrolysis the following electrolytes. [3 pt ea] 25 ºC. Ksp for Mg(OH)2 = 1.50 × 10 . [15 pt]
electrolyte anode cathode
Molten NaCl(s) ( Cl2 ) ( Na ) Mg(OH)2 ⇄ Mg2+ + 2 OH−
NaCl(aq) ( Cl2 ) ( H2 ) x x 2x
2+ − 2 2 −11
Na2SO4(aq) ( O2 ) ( H2 ) Ksp = [Mg ][OH ] = (x)(2x) = 1.50×10
−4
Solving, x = 1.55 × 10
PbSO4(aq)/H2SO4(aq) ( PbO2 ) ( Pb ) − −4
[OH ] = 2x=3.10 × 10 M; pOH = 3.51; pH = 10.5

4. Below is a table of some organic compounds with their IUPAC 10. Based on the following table of standard reduction potential,
names. Fill the blanks. [6 pt ea] answer the questions below.
IUPAC name structure half reduction reactions
o
E (V)
2+
Mg + 2e →-
Mg -2.47
( 1,4-cyclohexadiene )
Fe2+ + 2e- → Fe -0.44
( 3+
Fe + 3e
-
→ Fe +0.33
2-ethoxybutane
Cu2+ + 2e- → Cu +0.34
→
)
Ag+ + e- Ag +0.79
(a) Which ion is the strongest oxidant? [3 pt] ( Ag+ )
( 2,3-dimethylbutanol )
(b) Which metallic element can work as a sacrificial anode to
protect steel from corrosion? [3 pt] ( Mg )
( (c) Calculate emf of a cell made of Fe2+
(0.010 M)/Fe 3+
(0.10 M)
3-methyl-2-pentene
) half cell and H2(1.00 atm)/H+(pH = 2.00) half cell. Is H2 produced
( or consumed? [25 pt]
1,3-pentanediol
→
)
Fe2+ + 2e- Fe, Eo = -0.44 V
5. Write the IUPAC name or the systematic name. [7 pt ea] 3+
Fe + 3e →- o
Fe E = 0.33 V
(a) K2[Ni(CN)4] (potassium tetracyanonickelate(II) ) --------------------------
(b) [Co(NH3)4(OH2)Cl]Cl2 Fe3+ + e- → Fe2+ Eo = 0.77 V ----- ①
(tetraammineaquachlorocobalt(III) chloride ) +
2H + 2e →- o
H2 E = 0 V ------ ②
overall reaction: 2× ① ② - : 2Fe3+ + H2 → 2Fe2+ + 2H+
6. Write the chemical formula. [7 pt ea] 
  0.77 V
(a) Hexaaquachromium(III) nitrate ( [Cr(OH2)6](NO3)3 )
  V Fe   H 
(b) Dibromobis(ethylenediamine)cobalt(III) chloride      log  =
n Fe   pH
( [Co(en)2Br2]Cl )
 V  
 V   log  =0.95 V
  
7. Calculate the pH of a solution that is 0.20 M in sodium
H2 is consumed.
hypobromite (NaBrO) and 0.10 M in hypobromous acid (HBrO).
-9
(Ka is 2.5x10 ) [15 pt]
11. The ionization constant for the propanoic acid, C2H5COOH, is
Ka = 1.25 × 10–5. What is the percent ionization in a 0.725 M
   solution of propanoic acid? [15 pt]
    log   log ×   log   
   + –
C2H5COOH + H2O → H3O + C2H5COO
(0.725–x)M xM xM
8. How many moles of ammonia must be added to 2.00 L of
+ –
water so that it will just dissolve 0.010 mol of silver chloride, Ka = [H3O ][C2H5COO ]/[C2H5COOH]
-10
AgCl? (Ksp for AgCl = 1.8 × 10 , Kd for Ag(NH3)2 = 6.3 ×
+
= x /(0.725–x)=1.25 × 10–5
2

-8
10 ) [30 pt] assume x << 0.725 so
2 –6
x = 9.06 × 10 ;
+ − –3
AgCl + 2 NH3 ⇄ Ag(NH3)2 + Cl x = 3.01 × 10 M
−3 −3 −3 −3 –3
5.0 × 10 2(5.0 × 10 ) 5.0 × 10 5.0 × 10 % ioniz. = 3.01 × 10 /0.725*100%=0.415%
+ -
AgCl ⇄ Ag + Cl
+ −
Ksp = [Ag ][Cl ] = 1.8 × 10
−10
12. What is the pH of a 0.010 M H2SO4 solution. Ka2 for HSO4-
+ −10 − -2
[Ag ] = (1.8 × 10 )/[Cl ] = 1.2 x 10 ? [20 pt]
−10 −3 −8 +
= (1.8 × 10 )/(5.0×10 ) = 3.6 × 10 MAg
+
Ag(NH3)2 ⇄ Ag + 2 NH3
+
H2SO4 → HSO4- + H+
−8 - 2- +
+ 2 +
Kd = [Ag ][NH3] /[Ag(NH3)2 ] = 6.3 × 10 HSO4 ⇄ SO4 + H
−8 2 −3 −8  
(3.6 × 10 )[NH3] /(5.0 × 10 ) = 6.3 × 10      
      ×  
therefore, [NH3] = 0.094 M,    
−3
[NH3] = 0.094 + 2(5.0 × 10 ) = 0.104 M           
? mol NH3 = 2.0 L× (0.104 mol / L) = 0.21 mol    log   or 

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