5194, 97 :
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89 5194, 97.
8. , :
) 20,0 0,12 NaCN 15,0 0,09 HCl.
.
NaCN + HCl = HCN + NaCl
, , :
n0(NaCN) = 20,0 ∙ 103 ∙ 0,12 = 2,4 ∙ 103 ;
n0(HCl) = 15,0 ∙ 103 ∙ 0,09 = 1,35 ∙ 103 .
n0(NaCN) > n0(HCl), NaCN , , NaCN HCN :
n1(NaCN) = n0(NaCN) n0(HCl) = 2,4 ∙ 103 1,35 ∙ 103 =
= 1,05 ∙ 103 .
n1(HCN) = n0(HCl) = 1,35 ∙ 103 .
(V) 20 + 15 = 35 .
:
(NaCN) = 1,05 ∙ 103/ 35 ∙ 103 = 0,03 /.
(HCN) = 1,35 ∙ 103/ 35 ∙ 103 = 0,039 /.
, (7) :
pH = lg[(HCN) / (NaCN)] = 9,3 lg(0,039/0,03) = 9,18;
) 11,25 0,12 / NaCN 15,0 0,09 / HCl.
.
n(NaCN) = 11,25 ∙ 103 ∙ 0,12 = 1,35 ∙ 103 .
n(HCl) = 15,0 ∙ 103 ∙ 0,09 = 1,35 ∙ 103 .
n(NaCN) = n(HCl), 1,35 ∙ 103 HCN.
(V) 11,25 + 15,0 = 26,25 .
HCN :
(HCN) = 1,35 ∙ 103/ 26,25 ∙ 103 = 0,051 /.
(2) :
pH = 1/2 1/2 lg[(HCN)] = 1/2 ∙ 9,3 1/2 ∙ lg(0,051) = 5,3;
) 20,0 0,12 / NaCN 35,0 0,09 / HCl.
.
n0(NaCN) = 20,0 ∙ 103∙ 0,12 = 2,4 ∙ 103 .
n0(HCl) = 35,0 ∙ 103 ∙ 0,09 = 3,15 ∙ 103 .
n0(HCl) > n0(NaCN), . . HCl, HCl HCN :
n1(HCl) = 35,0 ∙ 103 ∙ 0,09 20,0 ∙ 103 ∙ 0,12 = 0,75 ∙ 103 ;
n1(HCN) = 20,0 ∙ 103 ∙ 0,12 = 2,4 ∙ 103 .
HCl HCN, .
|
|
(V) 20,0 + 35,0 = 55,0 .
HCl :
(HCl) = 0,75 ∙ 103/ 55,0 ∙ 103 = 0,014 /.
, (1) :
pH = lg[(HCl)] = lg(0,014) = 1,87.
9. , 10,0 0,1 / Na2HAsO4 16,0 0,1 / HCl.
. :
Na2HAsO4 + HCl = NaH2AsO4 + NaCl (10)
NaH2AsO4 + HCl = H3AsO4 + NaCl (11)
:
n(Na2HAsO4) = 10,0 ∙ 103 ∙ 0,1 = 1,0 ∙ 103 .
n(HCl) = 16,0 ∙ 103 ∙ 0,1 = 1,6 ∙ 103 .
Na2HAsO4 , HCl (10), (10) 1,0 ∙ 103 NaH2AsO4 (1,6 1,0) ∙ 103 =
= 0,6 ∙ 10 3 HCl. (11) H3AsO4 NaH2AsO4 :
n(NaH2AsO4) = 1,0 ∙ 103 0,6 ∙ 103 = 0,4 ∙ 103 ;
n(H3AsO4) = 0,6 ∙ 103 .
10 + 16 = 26 , 26 ∙ 103 . :
(NaH2AsO4) = 0,4 ∙ 103/ 26 ∙ 103 = 0,015 /;
(H3AsO4) = 0,6 ∙ 103/ 26 ∙ 103 = 0,023 /.
, (7) :
pH = lg((H3AsO4) / (NaH2AsO4)) =
= 2,22 lg(0,023/0,015) = 2,03.
95, 96 98100 .