Download - KA Materi 2
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LOGO
Reaksi Pengendapan
A.S.
MINGGU KE 2
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REAKSI PENGENDAPAN
two or more soluble species
combine to form
an insoluble product (precipi tate )
Pb2+ (aq ) + 2Cl –
(aq ) PbCl2(s )
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CONTOH
• pengendapan mineral akibatpembentukan garam kalsium di organginjal
• pembekuan darah
Reaksi dalam tubuh manusia:
Timbulnya kerak pada alat untukpemanasan air dengan kesadahan tinggi
Proses sehari-hari :
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PbCl
2
NaCl
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NaOH
HCl
Mg OH)
2
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Cl Ag AgCl
K
sp
= Solubility Product Constants
tetapan kesetimbangan/hasil kali kelarutan)
Cl Ag Ksp
Jumlah maksimum zat yang
dapat larut dalam sejumlah
pelarut
V
n s
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Q < Ksp Tak Jenuh (≠ endapan)
Q = Ksp Jenuh
Q > Ksp Lewat Jenuh (endapan)
s s s
CrO Ag CrO Ag
2
42
42 2
Q = hasil kali konsentrasi ion-ion
242CrO Ag Ksp
32
42 s s s Ksp
PREDIKSI TERBENTUK ENDAPAN
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Calculate [HCl] required to precipitate AgCl
from 100 mL 0.1 M AgNO3? (Ksp = 1.8 x 10-10)
Solution consist of 0.10 M Ag+ and 0.10 M Pb2+
Ksp AgBr = 3.3 x 10-13
Ksp PbBr 2 = 6.4 x 10-6
Plan: Add Br - until all AgBr is precipitate, but no
PbBr 2 is precipitate. Calculate [Br -] required to
precipitate!
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100 mL of 0.1 M potassium sulfate solution is added
to a 100 mL solution of 0.2 M barium nitrate.
Calculate the mass of the precipitate formed and
the concentration of remaining ions in the solution!
A solution contains 0.020 M Ag+ and Pb2+.Add CrO4
2- to precipitate red Ag2CrO4 and
yellow PbCrO4. Which precipitates first?Data: Ksp Ag2CrO4 = 9.0 x 10
-12
Ksp PbCrO4 = 1.8 x 10-14
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PROBLEM 6
a. Will a precipitate form when 150 mL of 0.1 M Pb(NO3)2 are
combined with 100 mL of 0.2 M NaCl?
Ksp = 1.2 x 10-5
b. What minimum concentration of Na2CO3(aq) is required to causeprecipitation of BaCO3(s) from a solution of 1.0 x 10
-5M BaCl2(aq)?
Ksp = 2.6 x 10-9
c. What compound, if any, will precipitate when 80.0 mL of 1.0 x 10-5
MBa(OH)2(aq) is dded to 20mL 1.0 x 10
-5M Fe2(SO4)3?
)()()( 22 aqCl aq Pb s PbCl
)()()( 2
3
2
3 aqCOaq Ba s BaCO
102
4
2
4 101.1)()()(
KspaqSOaq Ba s BaSO
393
3 106.2)()()(
KspaqOH aq Fe sOH Fe