Ngā Tauira Pātai e Matapaki ana i te Wairewatanga me te Wairewatanga Hua
He ariā nui te wairewatanga me te hua wairewatanga (Ksp) i roto i te matū e pā ana ki ngā otinga kua kī me te wairewatanga o tētahi matū i roto i te otinga. Mā te mārama ki tēnei kaupapa ka āwhina i a tātou ki te matapae i te wairewatanga o te tote i roto i te otinga, me te pānga o ngā āhuatanga maha ki taua wairewatanga. Ka matapakihia e tēnei tuhinga ētahi tauira raruraru me ā rātou otinga e pā ana ki te wairewatanga me te Ksp.
Ngā Ariā Taketake
Ko te wairewatanga (S) te nui rawa o tētahi matū ka taea te wairewa i roto i tētahi whakarewa hei hanga i tētahi otinga mātotoru i tētahi pāmahana kua whakaritea. I te nuinga o te wā, ka whakaatuhia te wairewatanga i roto i ngā waeine o te molarity (mol/L).
Ko te Hua Wairewatanga (Ksp) te pūmau taurite mō te wehenga o ngā irahiko e tino wairewa ana i roto i te wai. Ka whakaratohia e te Ksp ngā mōhiohio e pā ana ki te nui o te wairewa o te tote i roto i te wai, ā, ko te hua tēnei o ngā kukū o ngā irahiko i roto i te otinga kua kī, ia irahiko ka whakanuia ki te mana o tōna tauwehenga stoichiometric.
Hei tauira, mēnā he tote AxBy tā tātou e wehea ana hei iona e ai ki te whārite:
\[ \text{AxBy (s)} \right leftharpoons xA^{n+} (aq) + yB^{m-} (aq) \]
Nā reira, ka taea te tuhi i a Ksp penei:
\[ \text{Ksp} = [A^{n+}]^x [B^{m-}]^y \]
Ngā Tauira Pātai me ngā Kōrerorero
Tauira Pātai 1
Pātai:
Tātaihia te wairewatanga o \(AgCl\) (Ksp = \(1.8 \times 10^{-10}\)) i roto i te wai parakore.
Kōrero:
Ksp \(AgCl\) = 1.8 x \(10^{-10}\) mol²/L²
Tauhohenga wehewehe:
\[AgCl (s) \rightleftharpoons Ag^+ (aq) + Cl^- (aq)\]
Mehemea ko te wairewatanga o \(AgCl\) he S mol/L. Kātahi, ko ngā kukū o \(Ag^+\) me \(Cl^-\) i roto i te wairewa kua mākū ka ōrite ki te S mol/L.
Whārite Ksp:
\[Ksp = [Ag^+][Cl^-]\]
Whakakapia te uara o S:
\[1.8 \times 10^{-10} = S \times S\]
\[S^2 = 1.8 \whakareatia ki te 10^{-10}\]
\[S = \sqrt{1.8 \times 10^{-10}} \]
\[S = 1.34 \times 10^{-5} \, \text{mol/L}\]
Nō reira, ko te wairewatanga o \(AgCl\) i roto i te wai parakore ko \(1.34 \times 10^{-5}\) mol/L.
Tauira Pātai 2
Pātai:
He aha te wairewatanga o \(CaF_2\) (Ksp = \(3.9 \times 10^{-11}\)) i roto i te wai parakore?
Kōrero:
Tauhohenga wehewehe:
\[CaF_2 (s) \rightleftharpoons Ca^{2+} (aq) + 2F^- (aq)\]
Me kī ko te wairewatanga o \(CaF_2\) he S mol/L. Kātahi, ko te kukū o \(Ca^{2+}\) i roto i te wairewa kua mākū he S mol/L, ā, ko te kukū o \(F^-\) he 2S mol/L.
Whārite Ksp:
\[Ksp = [Ca^{2+}][F^-]^2\]
Whakakapia te uara o S:
\[3.9 \times 10^{-11} = S \times (2S)^2\]
\[3.9 \times 10^{-11} = S \times 4S^2\]
\[3.9 \whakareatia 10^{-11} = 4S^3\]
\[S^3 = \frac{3.9 \times 10^{-11}}{4}\]
\[S^3 = 9.75 \whakareatia ki te 10^{-12}\]
\[S = \sqrt[3]{9.75 \times 10^{-12}}\]
\[S \tata ki te 2.1 \times 10^{-4} \, \text{mol/L}\]
Nō reira, ko te wairewatanga o \(CaF_2\) i roto i te wai parakore ko \(2.1 \times 10^{-4}\) mol/L.
Tauira Pātai 3
Pātai:
He aha te wairewatanga o \(PbCl_2\) (Ksp = \(1.7 \times 10^{-5}\)) i roto i te otinga \(0.1\) M \(HCl\)?
Kōrero:
Tauhohenga wehewehe:
\[PbCl_2 (s) \rightleftharpoons Pb^{2+} (aq) + 2Cl^- (aq)\]
Me kī ko te wairewatanga o \(PbCl_2\) he S mol/L. Kātahi, ko te kukū o \(Pb^{2+}\) i roto i te wairewa kua mākū he S mol/L, ā, ko te kukū tāpiri o \(Cl^-\) mai i te wehenga o \(PbCl_2\) he 2S mol/L.
Heoi anō, kei reira anō te \(Cl^-\) mai i te \(HCl\) kua tae kē ki te 0.1 M te nui.
Whārite Ksp:
\[Ksp = [Pb^{2+}][Cl^-]^2\]
Whakakapia ngā uara o S me \(Cl^-\):
\[1.7 \times 10^{-5} = S \times (0.1 + 2S)^2\]
Nā te mea he nui ake te 0.1 M \(Cl^-\) i te 2S, \(0.1 + 2S \approx 0.1\).
Nō reira, ka māmā ake te tatau:
\[1.7 \times 10^{-5} = S \times (0.1)^2\]
\[1.7 \times 10^{-5} = S \times 0.01\]
\[S = \frac{1.7 \times 10^{-5}}{0.01}\]
\[S = 1.7 \times 10^{-3} \, \text{mol/L}\]
Nō reira, ko te wairewatanga o \(PbCl_2\) i roto i \(0.1\) M \(HCl\) ko \(1.7 \times 10^{-3}\) mol/L.
Tauira Pātai 4
Pātai:
Tātaihia te wairewatanga o \(BaSO_4\) (Ksp = \(1.1 \times 10^{-10}\)) i roto i tētahi otinga kei roto ko \(0.01\) M \(Na_2SO_4\).
Kōrero:
Tauhohenga wehewehe:
\[BaSO_4 (s) \right leftharpoons Ba^{2+} (aq) + SO_4^{2-} (aq)\]
Me kī ko te wairewatanga o \(BaSO_4\) he S mol/L. Kātahi, ko te kukū o \(Ba^{2+}\) i roto i te wairewa kua mākū he S mol/L, ā, ko te kukū o \(SO_4^{2-}\) o \(BaSO_4\) he S mol/L. Heoi anō, he \(0.01\) M \(SO_4^{2-}\) o \(Na_2SO_4\).
Whārite Ksp:
\[Ksp = [Ba^{2+}][SO_4^{2-}]\]
Whakakapia ngā uara o S me \(SO_4^{2-}\):
\[1.1 \times 10^{-10} = S \times (0.01 + S)\]
Nā te mea he nui ake a \(0.01\) M \(SO_4^{2-}\) i a S, \(0.01 + S \approx 0.01\).
Nō reira, ka māmā ake te tatau:
\[1.1 \times 10^{-10} = S \times 0.01\]
\[S = \frac{1.1 \times 10^{-10}}{0.01}\]
\[S = 1.1 \times 10^{-8} \, \text{mol/L}\]
Nō reira, ko te wairewatanga o \(BaSO_4\) i roto i tētahi otinga kei roto ko \(0.01\) M \(Na_2SO_4\) ko \(1.1 \times 10^{-8}\) mol/L.
Whakamutunga
Mā roto i ngā tauira raruraru i runga ake nei, ka taea e tātou te kite i te whakamahinga o ngā ariā o te wairewatanga me te hua wairewatanga (Ksp) i roto i ngā āhuatanga rerekē. He mea nui tēnei māramatanga i roto i te tātari matū, inā koa ka hiahia tātou ki te whakatau i te wairewatanga o tētahi tote motuhake i raro i ngā āhuatanga rerekē, pērā i roto i tētahi whakarewa parakore, i te aroaro rānei o tētahi katote noa. Mā te āheinga ki te whakaoti i ēnei raruraru ka āwhina i a tātou i roto i ngā tono mahi maha, tae atu ki ngā rongoā, te matū taiao, me te purenga rauemi.
He mea nui kia mōhiotia ko te wairewatanga o te tote ehara i te mea ko te uara Ksp anake, engari ka pāngia hoki e te kukū o ētahi atu iona i roto i te wairewa, te pāmahana, me te pH o te taiao. Mā te whakamahi i ngā mātāpono taketake o te matū me te tātaitanga māmā, ka taea e tātou te matapae me te whakahaere i ngā āhuatanga wairewatanga i roto i ngā pūnaha matū rerekē.
