D. Gevaña/ Chemistry 26.1 (2017)
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DETERMINATION OF SOLUBILITY CONSTANT OF Ca(OH) 2 D. Gevaña1 1
Electrical and Electronics Engineering Institute, College of Engineering, University of the Philippines, Diliman, Quezon City 1101
Performed Performed 17 Ja!ary 2017" #!$mitted 2% &e$r!ary &e$r!ary 2017
Answers to Questons !" #rte #rte t$e net on% e&uato e&uaton n 'or t$e re%tat re%taton on o' Ca(OH) Ca(OH) 2 an *+e t$e , s s e-resson o' t$e rea%ton" Ca(')2(s) ⇋ Ca2(a*) 2'+(a*) 2 + 2 , ss- Ca ' 2" #$at s t$e wor.n* wor.n* e&uato e&uaton n 'or t$e eter/na eter/naton ton o' t$e 0Ca 21 n t$e saturate so3uton o' Ca(OH) 24
+ ¿¿
H
¿
V
−¿¿
OH
Ca2
¿ ¿ ¿
¿
analyte,initial
¿¿ ¿ ¿ ¿
( V titrant ) ¿ ¿ ¿ 5" #rte t$e t$e , s s o' Ca(OH)2 n ter/s o' ts (a) /o3ar so3u63t7 38s8 (6) 9 0OH an (%) 0Ca21"
a$e a$e 1. 3C4 ta$e of the et ioi5 ioi5 e*!atio for the -re5i-itatio -re5i-itatio of Ca(')2 ⇋ Ca(')2(s) Ca2(a*) 2' (a*) 3 + 0 0 C + 2 4 + 2 (a) et s8 s8 9here s is the moar so!$iity so!$iity 2 + 2 , ss- Ca ' 2 : , ss- (s)(2s) %s OH ($) , ss-
¿ ¿ ¿ ¿
Ca ¿
(5) , ss-
2
2 +¿ ¿ ¿ 2¿
D. Gevaña/ Chemistry 26.1 (2017)
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:" Ds%uss t$e e;e%ts o' %o//on ons an n%reasn* on% stren*t$ on t$e so3u63t7 o' t$e Ca(OH)2 re%tate" Do t$e7 %on%e wt$ t$eoret%a3 e;e%ts4 E-3an"
;he a 5ommo io is added to a sat!rated so!tio of a ioi5 5om-o!d8 the so!$iity8 8 *!atity of so!te that dissoves to form a a*!eo!s so!tio8 is o9ered ad more of the 5om-o!d -re5i-itates 1. e5t8 the -rese5e of 5o!ter ios i the so!tio i5reases the so!$iity of the -re5i-itate $e5a!se of the esseed itera5tio $et9ee the ios of the -re5i-itate 1. his -ro5ess 5a $e sho9 9ith the itera5tio of the -otassi!m io 9ith the hydroide io ad the formatio of 5a5i!m 5horide as sho9 $eo9.
;ith the additio of ,C i Ca(') 2 so!tio8 ,C(s)
⇋
C+(a*) , (a*)
Ca(')2(s)
⇋
Ca2(a*) 2'+(a*)
<" #$at are t$e oss63e sour%es o' errors an t$er e;e%t on t$e %a3%u3ate ara/eters4 Ratona3=e"
Possi$e so!r5es of errors are im-ro-er meas!remet of the reagets. 3f the 5o5etratios of the reagets are ot a55!rate8 the it 9i 5hage the res!ts o$taied si5e it de-eds !-o the 5o5etratio of the s!$sta5e. <other fa5tor 9o!d $e tem-erat!re8 si5e the theoreti5a , s- of Ca(')2 is 6.? 10+6 at 2? C8 di>ere5e i tem-erat!re may have aready a>e5ted the e-e5ted ,s-. igher tem-erat!re i5reases so!$iity ad o9er tem-erat!re de5reases , s-. ast -ossi$e 5a!se 9o!d have $ee from the titratio -ro5ess. 3m-ro-er 9ay of titratig8 9rog meas!remet of the !sed vo!me of titrat et5.8 9i a ead to erroeo!s res!ts ad 5a5!atios. °
REFERENCES 1 #i$er$erg8 @.#. 2007. Principles of eneral Chemistry !nd Ed" =e9 AorB8 #< he @5Gra9+i Com-aies8 35. -- 6?:+6?% 2 3stit!te of Chemistry. Chem !#"1$ %nalytical Chemistry &a'oratory (anual. iversity of the Phii--ies Diima. 2017. Prit.
D. Gevaña/ Chemistry 26.1 (2017)
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A>>ENDI? CALCULATIONS 1. Determie the 5o5etratio (i moarity) of the stadard C so!tio. 0.1128 g Na2 CO3 mol Na2 CO3 2 mol HCl 1000 mL HCl = 0.79 M × × × a. 2.7 mL HCl 105.99 g 1 L mol Na2 CO3 0.1118 g Na 2 CO 3 mol Na2 CO 3 2 mol HCl 1000 mL HCl =0.81 M × × × $. mol Na2 CO 3 2.6 mL HCl 105.99 g 1 L mol Na2 CO 3 0.1378 g Na2 CO 3 2 mol HCl 1000 mL HCl =0.84 M × × × 5. 3.1 mL HCl 105.99 g 1 L mol Na2 CO 3 2. Determie the e-erimeta , s- ad moar so!$iity $ased o Determination of ) sp and (olar *olu'ility i 5om-ariso 9ith the theoreti5a , s- of Ca(')2 6.? 10+6 (at 2? ℃ ). Ca5!ate the E error.
# so!$iity of Ca(')2 Ca2 vol HCl× [ HCl ] ) ÷ 2 ad '+ 2Ca2 Ca2 ( vol filtrate 5.4 mL× [ 0.1 ] a. Ca2 ÷ 2=0.0054 50 mL '+ 2Ca2 2(0.00?%) 0.010F , s- %(0.00?%): 6.: × 10−7 theoretical −experimental Eerror 100E theoretical
(
)
|
|
−6 6.5 x 10
|
−6. 3 x 10−
−6 6.5 x 10
7
|
F6.%6E
≈ 86
D. Gevaña/ Chemistry 26.1 (2017)
(
$. Ca2
[
5.6 mL× 0.1
]
50 mL
)
Page | %
÷ 2 =0.0056
'+ 2Ca2 2(0.00?6) 0.0112 , s- %(0.00?6): 7.0 × 10−7 theoretical −experimental Eerror 100E theoretical
|
|
−6 6.5 x 10
|
−7 . 0 x 10−
7
−6 6.5 x 10
(
5. Ca2
|
F.2:E
[
5.7 mL× 0.1
]
50 mL
)
≈89
÷ 2 =0.0057
'+ 2Ca2 2(0.00?7) 0.011% , s- %(0.00?7): 7.? × 10−7 theoretical −experimental Eerror 100E theoretical
|
|
−6 6.5 x 10
−7.5 x 10−
−6 6.5 x 10
|
7
|
FF.%6E
≈88
:. Determie the so!$iity of Ca(')2 i E+ect of Common Ions on the *olu'ility of Ca-./ !" s so!$iity of Ca(') 2 Ca2 vol HCl× [ HCl ] ) ÷ 2 ad '+ 2Ca2 Ca2 ( vol filtrate
(
a. Ca2
[
5.5 mL× 0.1
]
50 mL
)
÷ 2= 0.005 5 s
'+ 2Ca2 2(0.00??) 0.0110
(
$. Ca2
[
5.7 mL× 0.1
]
50 mL
)
÷ 2= 0.005 7 s
'+ 2Ca2 2(0.00?7) 0.011% %.?.
Determie the ioi5 stregth of di>eret ,C so!tios ad the so!$iity of Ca(')2 i E+ect of Ionic *trength on the *olu'ility of Ca-./ !" s so!$iity of Ca(') 2 Ca2 vol HCL× [ KCL ] ) ÷ 2 ad '+ 2Ca2 Ca2 ( vol filtrate
μ=
1
∑ C i
2
i
2
9here Ci ad Hi are 5o5etratios (i moarity) ad
5harges of the ios8 res-e5tivey. 0.010 @ ,C a. Ca2
(
[
5.6 mL× 0.010 50 mL
]
)
÷ 2 =0.0 0056 s
'+ 2Ca2 2(0.000?6) 0.00112
D. Gevaña/ Chemistry 26.1 (2017)
$. Ca2
(
[
]
5.3 mL× 0 . 0 1 0 50 mL
)
÷ 2 =0 . 0 0 0 5 3 s
'+ 2Ca2 2(0.000?:) 0.00106 0.0?0 @ ,C a. Ca2
(
[
6.2 mL × 0.050
]
50 mL
)
÷ 2= 0.0031 s
'+ 2Ca2 2(0.00:1) 0.0062 $. Ca2
(
[
]
6 .3 mL× 0 . 0 5 0 50 mL
)
÷ 2= 0.00 315 s
'+ 2Ca2 2(0.00:1?) 0.006:
0.10 @ ,C a. Ca2
(
[
6.0 mL× 0.10
)
]
50 mL
÷ 2=0.0 06 s
'+ 2Ca2 2(0.006) 0.012 $. Ca2
(
[
5.9 mL× 0.10
]
50 mL
)
÷ 2= 0.0059 s
'+ 2Ca2 2(0.00?) 0.011F 0.2? @ ,C a. Ca2
(
[
6 .6 mL× 0.25
)
]
50 mL
÷ 2 =0.0165 s
'+ 2Ca2 2(0.016?) 0.0:: $. Ca2
(
[
6.7 mL× 0.25
]
50 mL
)
÷ 2 =0.0 1675 s
'+ 2Ca2 2(0.0167?) 0.0::? 0.?0 @ ,C a. Ca2
(
[
7.2 mL × 0.50
]
50 mL
)
÷ 2=0.0 36 =!
'+ 2Ca2 2(0.0:6) 0.072 $. Ca2
(
[
7.0 mL× 0.50 50 mL
]
)
÷ 2= 0.035 s
'+ 2Ca2 2(0.0:?) 0.07
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