general chemistry 6

7/31/2019 General Chemistry 6

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1 General Chem, Usama El-Ayaan


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2 General Chem, Usama El-Ayaan


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3

H2, Cl2, P4, F2, O2, O3, Na, Li, Mg

K+ = +1 , O2- = -2 , Al3+ = +3

General Chem, Usama El-Ayaan


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4

=-2(H2O2, Na2O2)=

-1(KO2)=-0.5

=+1(

NaH, CaH2)LiAlH4, NaBH4=-1.



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5

:



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For KClO4: (K=+1, O=-2, Cl=??)

[+1 (for K+)] + [Cl ???] + [4 X(-2) for oxygen] = zero

+1 + Cl - 8 = 0 , Cl7 = 0 Cl = +7 (not -1)

For Na2S4O6: (Na=+1, O=-2, S=??)

[(+1 x 2) (for 2 Na+)] + [4 S ???] + [6 X(-2) for oxygen]

= zero

+2 + 4S - 12 = 0 , 4S10 = 0 S = + 2.5 ( )



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Redox Reactions

Na + 2Cl2 2NaCl

CH4 + 2O2 CO2 + 2H2O



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:

Fe(s) + O2(g) Fe2O3(s)

Fe2O3(s)+ 3 CO(g) 2 Fe(l) + 3 CO2(g)

SO3

2- + H+ + MnO4

- SO4

2- + H2

O + Mn2+



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9

()

1-

(.)

2-

3-:



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2H+OH2O

H+H

H2OO2 OH-

OH-HH2O



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1-Fe2+ + Cr2O72- Fe3+ + Cr3+

:

Cr2O72- Cr3+ ) )

Cr2O72- 2 Cr3+

Cr2O72- + 14 H+ 2 Cr3++ 7 H2O

Cr2O72- + 14 H++ 6 e- 2 Cr3+ + 7 H2O (a)



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12

Fe2+

Fe3+

()

Fe2+ Fe3+

Cr2O72- + 14 H++ 6e- 2 Cr3+ + 7 H2O (a)

6 Fe2+ 6 Fe3+ + 6e- (b)

Cr2O72-

+ 14 H+

+ 6 Fe2+

2 Cr3+

+ 7 H2O + 6 Fe3+



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2-

: MnO4

- + SO32- + H+ SO4

2- + Mn2+

MnO4- Mn2+

MnO4-

+ 8 H+

Mn2+

+ 4 H2O

MnO4- + 8 H++ 5e- Mn2+ + 4 H2O (a)

SO32- SO4

2-

SO32-+ H2O SO42-+ 2 H+SO3

2- + H2O SO42- + 2 H+ + 2e- (b)



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2 MnO4- + 16 H+ + 10 e- 2 Mn2+ + 8 H2O (a)

5 SO32- + 5 H2O 5 SO42- + 10 H+ + 10 e- (b)

2 MnO4- + 6 H+ + 5 SO3

2- 2 Mn2+ + 3 H2O + 5 SO42-



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Cr2O72- Cr3+

Cr2O72- 2 Cr3+

Cr2O72-+ 14 H+ 2 Cr3++ 7 H2O

Cr2O72- + 14 H++ 6 e- 2 Cr3+ + 7 H2O (a)

CH3CH2OH CH3CHO

C2H6O C2H4O

C2

H6

O C2

H4

O + 2H+

C2H6O C2H4O+ 2H+ + 2 e- (b)

3 C2H6O 3 C2H4O + 6 H+ + 6 e- (b)

Cr2O72- + 14 H++ 6 e- 2 Cr3+ + 7 H2O (a)

Cr2O72- + 8 H+ + 3 C2H6O 2 Cr

3+ + 7 H2O + 3 C2H4O



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:MnO4-

+ SO32-

+ OH-

SO42-

+ MnO2

MnO4- MnO2

MnO4- + 2 H2O MnO2 + 4 OH

-

MnO4- + 2 H2O + 3 e

- MnO2 + 4 OH- (a)

SO32- SO4

2-

SO32-+ 2 OH- SO4

2-+ 1 H2O

SO32- + 2 OH- SO4

2- + 1 H2O+ 2 e- (b)

2 MnO4- + 4 H2O + 6 e

- 2 MnO2 + 8 OH- (a)

3 SO32- + 6 OH- 3 SO42- + 3 H2O+ 6 e- (b)

2 MnO4- + H2O + 3 SO3

2- 2 MnO2 + 2 OH- + 3 SO4

2-



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Al [Al(OH)4]-

Al + 4 OH- [Al(OH)4]-

Al + 4 OH- [Al(OH)4]- + 3 e- (a)

NO3- NH3

NO3- + 3 H2O NH3 + 6 OH

-

NO3- + 3 H2O + 3 H2O NH3 + 6 OH

- + 3 OH-

NO3- + 6 H2O NH3 + 9 OH

-

NO3- + 6 H2O + 8 e

- NH3 + 9 OH- (b)

8 Al + 32 OH- 8 [Al(OH)4]- + 24 e- (a)

3 NO3- + 18 H2O + 24 e

- 3 NH3 + 27 OH- (b)

8 Al + 5 OH- + 3 NO3- + 18 H2O 8 [Al(OH)4]

- + 3 NH3



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:

Pb(OH)3- + OCl- PbO2 + Cl

-Pb(OH)

3

- PbO2

Pb(OH)3- PbO2+ 3OH

- ( )

Pb(OH)3- + 4 OH- PbO2 + 3OH

- + 2 H2O ( )

Pb(OH)3- + OH- PbO2 + 2 H2O + 2 e

-( )

Pb(OH)3- + OH- PbO2 + 2 H2O + 2 e

- (a)

OCl- Cl-

OCl- + H2O Cl- + 2 OH- ( )

OCl- + H2O + 2 e- Cl- + 2 OH- (b)

Pb(OH)3- + OH- PbO2 + 2 H2O + 2 e

- (a)

OCl- + H2O + 2 e- Cl- + 2 OH- (b)

Pb(OH)3- + OCl- PbO2 + H2O + Cl

- + OH-



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Ionic Equilibrium



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(1884)

(H+)

(OH-aq)

(NH3)



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-Bronsted & lowry(1923)

HCl(g) + H2O(l) H3O+ + Cl-

()().



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Pairs

""

HCl(g) + H2O(l) H3O+ + Cl-

base (y) + base (x)acid (y)+acid (x)



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CH3COO-

CH3COOHNH3 ()NH4

+

HCO-3 ()H2CO3



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2H2O (l) H3O+(aq) + OH-(aq)

Kc =[H3O

+][OH-]

[H2O]2 [H2O]

2 = constant

Kc[H2O]2 =Kw = [H

+][OH-]

The ion-product constant(Kw)



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At 250

C Kw= [H

+][OH-] = 1.0 x 10-14

[H+] = [OH-]

[H+] > [OH-]

[H+] < [OH-]

Neutral

Acidic

Basic



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pH (A Measure of Acidity)

pH = -log [H+]

[H+] = [OH-]

[H+] > [OH-][H+] < [OH-]

[H+] = 1 x 10-7

[H+] > 1 x 10-7

[H+] < 1 x 10-7

pH = 7

pH < 7pH > 7

7

10-14 M H+10-1 M H+ 10-7 M H+

1 14



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pOH

pOH = -log [OH-]

[H+][OH-] =Kw = 1.0 x 10-14

-log [H+]

log [OH-] = 14.00

pH + pOH = 14.00

:HCl, NaOH0.01 M



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HCl H+ + Cl- ( )0.01 M 0.01 M 0.01 M

NaOH Na+ + OH- ( )0.01 M 0.01 M 0.01 M

pOH = -log [OH-] = -log 0.01 = 2 pH = 142 = 12 ( 7 )

pH = -log [H+] = -log 0.01 = 2 ( 7 ) pOH = 142 = 12

:HCl, NaOH0.01 M



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Ka [HA] = [H+][A-] = [H+]2

[H+] =

log [H

+

]= (-log Ka - log [HA])pH = [pKa log Ca]



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0.1M.

1.82 x 10-5

pH = )pKa log [HA]) = [-log (1.82x10-5) log (0.1)] = [4.74 + 1] = [5.74] = 2.87 log [H+] =2.87 [H+] = 102.87 = 1.35 x 103 = 0.00135

()=

= [Ka/Ca]1/2 = (1.8x10-5/0.1)1/2 = 0.013416



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(Buffer Solution)

.

.



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CH3COOH

H+

+ CH3COO-

CH3COONa Na+ + CH3COO

-

Ka =[H+][CH3COO-][CH3COOH]

Ka =[H+] Cs

Ca[H+] = KaCa

Cs

Log [H+] = log Ka + logCa

Cs

pH = pKa + log

Cs

Ca



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general chemistry 6

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