Milmitaanka iyo Ksp: inta milmaysa, iyo goorta ay dhaadhacdo

Qorista tibxaha wax-soo-saarka milmitaanka

Marka walax adag oo ayoon ah oo wax yar milma ay taabato xalkeeda dheregsan, milidda iyo dhaadhacu waxay ku dhacaan xawaare siman. Calcium fluoride, CaF₂(s) ⇌ Ca²⁺(aq) + 2 F⁻(aq), joogtada isu-dheellitirkuna waa Ksp = [Ca²⁺][F⁻]². Walaxda adag waa laga saaraa sababtoo ah waa xaalad saafi ah.

Uruurin ayoon kasta waxaa kor loogu qaadaa awoodda isku-dhuftihiisa ee isleegga milidda. Silver chromate, Ag₂CrO₄(s) ⇌ 2 Ag⁺(aq) + CrO₄²⁻(aq), Ksp = [Ag⁺]²[CrO₄²⁻]. Lead(II) iodide, Ksp = [Pb²⁺][I⁻]².

Milmitaanka molarka, s, waa tirada moolasha walaxda adag ee ku milma litir kasta oo xal dheregsan ah. Wuxuu Ksp kula xidhan yahay istoikiyomitariga milidda, sidaa darteed Ksp iyo milmitaanku ma aha isla tiro mana la barbar dhigi karo si toos ah cusbooyinka noocyada qaacidadoodu kala duwan yihiin.

Laga bilaabo Ksp ilaa milmitaanka molarka

Tusaale la xaliyey 1. Silver chloride wuxuu leeyahay Ksp = 1.6 × 10⁻¹⁰ Lifaaqa J. Haddii s mol/L milmo, [Ag⁺] = [Cl⁻] = s, sidaa darteed Ksp = s². Markaa s = √(1.6 × 10⁻¹⁰) = 1.3 × 10⁻⁵ M. Iyadoo M(AgCl) = 143.32 g/mol, taasi waa 1.8 × 10⁻³ g litir kasta, dhawr milligaraam.

Tusaale la xaliyey 2. Calcium fluoride wuxuu leeyahay Ksp = 4.0 × 10⁻¹¹. Haddii s mol/L milmo, [Ca²⁺] = s iyo [F⁻] = 2s, sidaa darteed Ksp = s(2s)² = 4s³. Markaa s = (4.0 × 10⁻¹¹ / 4) oo kor loogu qaaday awoodda 1/3 = 2.2 × 10⁻⁴ M.

Barbar dhig labada. AgCl wuxuu leeyahay Ksp ka weyn, hase yeeshee CaF₂ wuxuu qiyaastii 17 jibaar ka milmo badan yahay mool litir kasta. Jibbaarku wuxuu beddelaa sida Ksp ugu dhigmo milmitaanka, sidaa darteed milmitaanka Ksp ku kala horraysiin kartaa oo keliya cusbooyinka leh isla saamiga ayoonnada.

• Cusbooyinka 1:1 sida AgCl ama CaCO₃: Ksp = s².
• Cusbooyinka 1:2 ama 2:1 sida CaF₂, PbI₂ ama Ag₂CrO₄: Ksp = 4s³.
• Cusbooyinka 1:3 sida Al(OH)₃: Ksp = 27s⁴.

Laga bilaabo milmitaan la cabbiray dib ugu noqoshada Ksp

Xisaabtu sidoo kale waxay u socotaa dhinaca kale. Ka soo qaad in xal dheregsan oo lead(II) iodide ah 25 °C lagu ogaaday inuu ka kooban yahay 0.70 g oo PbI₂ la milay ah litir kasta. Iyadoo M(PbI₂) = 461.0 g/mol, s = 0.70 / 461.0 = 1.52 × 10⁻³ M.

PbI₂ kasta oo milma wuxuu bixiyaa hal Pb²⁺ iyo laba I⁻, sidaa darteed [Pb²⁺] = 1.52 × 10⁻³ M iyo [I⁻] = 3.04 × 10⁻³ M. Markaa Ksp = (1.52 × 10⁻³)(3.04 × 10⁻³)² = 1.4 × 10⁻⁸, taasoo waafaqsan qiimaha Lifaaqa J. Laba khalad ayaa halkan caadi ah. Illaawidda arrinta 2 ee [I⁻] waxay Ksp ka dhigtaa afar jibaar aad u yar. Illaawidda labajibaarinta [I⁻] waxay bixisaa awood khaldan oo s ah gabi ahaanba.

Ku darista ayoon guud waxay xakamaysaa milmitaanka

Haddii xalku horey uga kooban yahay mid ka mid ah ayoonnada cusbada, mabda'a Le Chatelier wuxuu isu-dheellitirka milidda dib ugu riixaa xagga walaxda adag. Tani waa saameynta ayoonka guud (common-ion effect).

Tusaale la xaliyey. Hel milmitaanka AgCl ee 0.10 M NaCl. Hadda [Cl⁻] = 0.10 + s, s-na aad buu ugu yar yahay marka loo eego 0.10, sidaa darteed [Cl⁻] ≈ 0.10 M. Markaa s = Ksp / [Cl⁻] = 1.6 × 10⁻¹⁰ / 0.10 = 1.6 × 10⁻⁹ M. Taasi waa qiyaastii 8,000 jibaar ka hooseeya biyaha saafiga ah, s-na si cad waa la tixgelin karin marka loo eego 0.10, sidaa darteed qiyaastu way shaqaynaysaa.

CaF₂ ee 0.010 M NaF, [F⁻] ≈ 0.010 M iyo s = 4.0 × 10⁻¹¹ / (0.010)² = 4.0 × 10⁻⁷ M, qiyaastii 540 jibaar ka hooseeya biyaha saafiga ah. Xasuuso inaad halkan labajibaarto uruurinta fluoride-ka, sida tibxaha Ksp oo kale.

Ma dhaadhici doontaa? Barbar dhigga Q iyo Ksp

Si aad u saadaaliso haddii isku darka laba xal uu soo saaro walax adag, ka xisaabi wax-soo-saarka ayoonka Q uruurinta kadib isku darka oo barbar dhig Ksp. Haddii Q ka weyn yahay Ksp, xalku waa dheregsan-dhaaf (supersaturated) dhaadhacna wuu samaysmaa. Haddii Q ka yar yahay ama le'eg yahay Ksp, wax adag ma samaysmaan.

Tusaale la xaliyey. Isku dar 50.0 mL oo 0.0010 M Pb(NO₃)₂ ah iyo 50.0 mL oo 0.0020 M KI ah. Isku darku wuxuu laba-laabaa mugga, sidaa darteed uruurin kastaa badh ayay noqotaa: [Pb²⁺] = 5.0 × 10⁻⁴ M iyo [I⁻] = 1.0 × 10⁻³ M. Q = (5.0 × 10⁻⁴)(1.0 × 10⁻³)² = 5.0 × 10⁻¹⁰. Taasi way ka hoosaysaa Ksp = 1.4 × 10⁻⁸, sidaa darteed PbI₂ ma dhaadhaco.

Ku celi 0.020 M KI. Hadda [I⁻] = 1.0 × 10⁻² M kadib isku darka iyo Q = (5.0 × 10⁻⁴)(1.0 × 10⁻²)² = 5.0 × 10⁻⁸. Taasi way dhaaftaa Ksp, sidaa darteed PbI₂ jaalle ah ayaa samaysma. Illaawidda khafiifinta isku darka waa khaladka ugu caamsan mushkiladahan.

Dhaadhicin xulasho leh: kala saarista ayoonnada Ksp

Marka laba ayoon mid kastaa la dhaadhici karo isla reagent, kan cusbadiisu u baahan tahay uruurinta reagent-ka ee ka hooseysa ayaa marka hore dhaadhaca. Ku darista tartiibta ah ayaa markaa kala saari karta.

Tusaale la xaliyey. Xal ayaa ah 0.010 M labada Cl⁻ iyo CrO₄²⁻, Ag⁺-na si tartiib ah ayaa loogu daraa. AgCl wuxuu bilaabaa inuu samaysmo marka [Ag⁺] = 1.6 × 10⁻¹⁰ / 0.010 = 1.6 × 10⁻⁸ M. Ag₂CrO₄, oo leh Ksp = 9.0 × 10⁻¹² ee Lifaaqa J, wuxuu bilaabaa inuu samaysmo marka [Ag⁺]² × 0.010 = 9.0 × 10⁻¹², sidaa darteed [Ag⁺] = 3.0 × 10⁻⁵ M. AgCl ayaa marka hore dhaadhaca.

Marka Ag₂CrO₄ casaanka ahi soo muuqdo, [Cl⁻] wuxuu hoos ugu dhacay 1.6 × 10⁻¹⁰ / 3.0 × 10⁻⁵ = 5.3 × 10⁻⁶ M, sidaa darteed oo keliya qiyaastii 0.05 boqolkiiba chloride-ka ayaa xalka ku haray. Isbeddelka midabka ee fiiqan waa aasaaska cabbiraadda Mohr ee chloride.

Sababta cusbooyinka qaarkood ugu milmaan si ka badan aashitada

Haddii anion-ka cusbadu yahay saldhig, sida OH⁻, CO₃²⁻ ama F⁻, ku darista aashitadu waxay anion-kaas ka saartaa xalka waxayna milidda u jiidaa hore. Hydroxide-yada iyo carbonate-yadu aad bay ugu milmaan pH hoose. Cusbooyinka anion-yada aashitada xooggan, sida AgCl, sidan uma saameeyaan.

Tusaale la xaliyey. Magnesium hydroxide wuxuu leeyahay Ksp = 8.9 × 10⁻¹². Biyo saafi ah, Ksp = 4s³ wuxuu bixiyaa s = 1.3 × 10⁻⁴ M iyo [OH⁻] = 2.6 × 10⁻⁴ M, sidaa darteed xal dheregsan wuxuu leeyahay pH 10.42. Haddii buffer halkii pH-ga ku hayo 9.00, markaa [OH⁻] = 1.0 × 10⁻⁵ M iyo s = 8.9 × 10⁻¹² / (1.0 × 10⁻⁵)² = 0.089 M, ku dhawaad 700 jibaar ka badan. Tani waxay u qaadanaysaa in buffer-ku leeyahay awood ku filan oo uu ku nuugo hydroxide-ka la sii daayo.

Khaladaadka Ksp ee la hubiyo kahor intaadan gudbin

Khaladaadka badankoodu waxay ka yimaadaan istoikiyomitariga milidda, ma aha fikradda isu-dheellitirka laftiisa. Qorista isleegga milidda iyo erayada s ee hoostiisa ayaa qabta intooda badan.

• Dejinta Ksp mid le'eg s² cusbo sii daysa saddex ayoon ama ka badan.
• Laba-laabidda uruurinta ayoon laakiin aan labajibaarin tibxaha, ama ka soo horjeedka.
• Ku kala horraysiinta milmitaanka Ksp cusbooyinka leh saamiyo ayoon oo kala duwan.
• Illaawidda khafiifinta labada xal marka la xisaabinayo Q kadib isku darka.
• Iska indho tirka ayoon guud oo horey u jira.
• Ku darista walaxda adag tibxaha Ksp.