cân bằng ion
DESCRIPTION
Cân Bằng IonTRANSCRIPT
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Chng 10
CN BNG ION TRONG DUNG DCH
10.1. Cn Bng Ion Ca Nc Trong Dung Dch
10.2. Cn Bng Ion Ca Acid Baze
10.2.1. Khi nim v acid v baze.
10.2.2. Cch tnh pH ca cc dung dch
10.2.3. Dung dch m.
10.3. Cn Bng Thy Phn Trong dd Mui.
Chng 10
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Cn Bng Ion Ca Nc Trong Dung Dch
10.1
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10.1 Cn Bng Ion Ca Nc Trong DD
10.1.1. S ion ha ca nc v tch s ion canc
dn in ca H2O = 5,54.10-18-1.cm-1 nc l cht in ly rt yu:
H2O + H2O H3O+ + OH-Hay: H2O H+ + OH-Hng s in ly ca nc:
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[ ][ ][ ]
16OH
OHH 1,8.10K2
==
+
[ ][ ] [ ] n14162 K 10181000
.1,8.10OHKOHH ==== +
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10.1 Cn Bng Ion Ca Nc Trong DD
10.1.2. Ch s pH v mi trng dung dch Nc nguyn cht c mi trng trung tnh:
[H+] = [OH-] = 10-7 pH = -lg[H+] = 7 Dung dch c mi trng acid:
[H+] > [OH-] pH < 7 Dung dch c mi trng baze:
[H+] < [OH-] pH > 7
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Cn Bng Ion Ca Acid Baze
10.2
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10.2. Cn Bng Ion Ca Acid Baze
10.2.1. Khi nim v acid v baze.Thuyt c in ca Arrhenius Acid: cht in ly cho ion H+
Baze: cht in ly cho ion OH-
Thuyt proton ca Bronsted Acid l cht c kh nng cho proton: HA = H+ + A-
Baze l cht c kh nng nhn proton: B + H+ = BH+
Cc cp HA/A- v B/BH+ l cc cp acid baze linhp.
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10.2. Cn Bng Ion Ca Acid Baze
10.2.1. Khi nim v acid v baze. S in ly ca Acid v baze trong nc:Acid: HA + H2O A- + H3O+
c trng cho mnh ca axit
Baze: B + H2O BH+ + OH-
c trng cho mnh ca baz
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[ ][ ][ ]HA
AOHK a
+
=3
[ ][ ][ ]B
OHBHKb+
=
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10.2. Cn Bng Ion Ca Acid Baze
10.2.1. Khi nim v acid v baze. S in ly ca Acid v baze trong nc:nh ngha: pKa = -lgKa
pKb = -lgKb
i vi mi cp acid baze lin hp, ta u c:pKa + pKb = pKn = 14
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10.2. Cn Bng Ion Ca Acid Baze
10.2.2. Cch tnh pH ca cc dung dch. pH ca dung dch acid mnh v baze mnh.o Acid mnh:
o Baze mnh:
pH ca dung dch acid yu v baze yu.o Acid yu:
o Baze yu:10
aCpH lg=
bCpH lg14 +=
( )aa CpKpH lg21
=
( )bb CpKpH lg2114 =
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10.2. Cn Bng Ion Ca Acid Baze
10.2.3. Dung dch mnh ngha: Dung dch m l dd c ga tr pH xcnh, hu nh khng thay i khi pha long hoc thmvo mt lng nh acid hay baze mnh.
Cu to ca dd m: gm mt acid yu v mui ca n(h m acid) hay gm mt baze yu v mui ca n (hm baze).V d:
CH3COOH CH3COO- + H+
CH3COONa CH3COO- + Na+11
10.2. Cn Bng Ion Ca Acid Baze
10.2.3. Dung dch mm acid:
m baze:
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m
a
a CC
pKpH lg=
=
m
bb C
CpKpH lg14
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Cn Bng Thy Phn Trong dd Mui
10.3
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10.3. Cn Bng Thy Phn Trong dd Mui10.3.1. S thy phnCc mui c lin kt ion nn khi ha tan trong nc sb phn ly hon ton thnh cc ion hydrat ha
MA M+.aq + A-
Cc cation kim loi b hydrat ha l cc acid Bronsted.Nu n l acid mnh hn nc, n s nhng H+ chonc v ngi ta ni cation b thy phn
[M(H2O)x]n+ +H2O [M(H2O)x-1OH](n-1)+ + H3O+Cc anion l cc baze Bronsted. Nu n l baze mnhhn nc, n s nhn H+ ca nc v ngi ta ni anion b thy phn:A- + H2O HA + OH-
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10.3. Cn Bng Thy Phn Trong dd Mui
10.3.2. pH ca dung dch mui
Mui ca acid mnh v baze yu: ch c cation ca mui b thy phn, dung dch mui c mi trng acid :
Mui ca acid yu v baze mnh: ch c anionca mui b thy phn, dung dch mui c mitrng baze :
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( )mb CpKpH lg217 +=
( )ma CpKpH lg217 ++=
10.3. Cn Bng Thy Phn Trong dd Mui
10.3.2. pH ca dung dch mui
Mui ca acid yu v baze yu: c cation vanion b thy phn, pH ca dung dch mui s doion b thy phn mnh hn quyt nh:
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( )ba pKpKpH += 217