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Group IV

Group IV. The Ammonium Carbonate Group Ca 2+ , Sr 2+ , Ba 2+. 目的 學習 第四族 陽離子的分離與確定,精練操作技術與原理應用。. 原理 BaSO 4 非常的不溶,溶解度為 1.1×10 -10 。 CaSO 4 少溶,溶解度為 2.4×10 -5 , SrSO 4 少溶,溶解度為 3.2×10 -7 。. Note (1) Ba 2+ + CrO 4 2- 會形成 BaCrO 4 黃色 沉澱, 可以證明 Ba 2+ 的 存在。

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Group IV

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  1. Group IV The Ammonium Carbonate Group Ca2+, Sr2+, Ba2+

  2. 目的 學習第四族陽離子的分離與確定,精練操作技術與原理應用。 原理 BaSO4非常的不溶,溶解度為1.1×10-10。CaSO4少溶,溶解度為2.4×10-5, SrSO4少溶,溶解度為3.2×10-7。 Note (1) Ba2+ + CrO42-會形成BaCrO4黃色沉澱,可以證明Ba2+的存在。 (2) CaC2O4是弱酸的鹽類,可以溶於強酸中,因此要形成CaC2O4沉澱必須在鹼性條件下。 (3) Na2CO3當日現配。

  3. 1滴 6 M NH4Cl 15 M NH3→ base + 5滴 (NH4)2CO3 Group IV: 各3滴 Ca2+, Sr2+, Ba2+, 7滴 NH4+ ∆ 溫水 ppt 6-1 + 6 M HOAc + 3 M NH4C2H3O2 + 10 滴 H2O + K2CrO4 sol 6-1 base + 1 滴 (NH4)CO3 沉澱完全後, +HCl→ acid ppt 6-2 + 6 M HCl + 1 mL H2O + ¼ 刮勺 HNH2SO3 ∆ 10 mins sol 6-2 + 6 M NaOH→ base + 5滴 Na2CO3 Group V ppt 6-3 + 2-4 滴 HNO3, 坩鍋 ∆ 冷卻,+5滴 16 M HNO3 ×2 cold path (stir) BaSO4↓ 沉澱 (黃色) ppt 6-4 + 5- 10 滴 H2O + NH3 → base + 三乙醇胺 +(NH4)SO4 sol 6-4 + 1 mL H2O + 15M NH3 → base + (NH4)2C2O4 SrSO4↓ 沉澱 (白色) CaC2O4↓ 沉澱 (白色) 1. Sr2+ + 2NO3-→ Sr(NO3)2↓ 2. Sr(NO3)2↓→ Sr2+ + 2NO3- 3. Sr2+ + SO4-→ SrSO4↓

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