1 / 3

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 第四族是在 (NH 4 ) 2 CO 3 與 NH 3 -NH 4 Cl 的緩衝溶液中形成沉澱物以便與其他陽離子分離 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

charde-hancock
Download Presentation

Group IV

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 第四族是在 (NH4)2CO3與 NH3-NH4Cl 的緩衝溶液中形成沉澱物以便與其他陽離子分離 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. + 1d6 M NH4Cl + 15 M NH3鹼化 + 5d(NH4)2CO3 Ba2+ + CO32-→ BaCO3(s) Ca2+ + CO32-→ CaCO3(s) Sr2+ + CO32-→ SrCO3(s) Group IV: 各3滴 Ca2+, Sr2+, Ba2+, 7滴 NH4+ * 加熱太久(NH4)2CO3會分解藥劑量會不足 Stir & ∆ Warm water (<1 min) sol 6-1 Check base + 1d(NH4)2CO3 ppt transfer to ppt 6-1 +HCl酸化 ppt 6-1 + 1~2d 6 M HOAc + 1~3d 3 M NH4C2H3O2 + 10dH2O + 1~3d K2CrO4 * Ba2+ + CrO42-→ BaCrO4(s) 補充CO32-，此溶液儲存太久會將玻璃溶出SiO2降低CO32-濃度 Ca2+ + CO32-→ CaCO3(s) Sr2+ + CO32-→ SrCO3(s) Group V sol 6-2 + 6 M NaOH 鹼化 + 5 drop Fresh Na2CO3 ppt 6-2 + 1~2 d 6 M HCl + 1 mL H2O + ¼ 刮勺 HNH2SO3 ∆Hot water (10 min) * 離心後溶液重複此動作直到無沉澱產生，沉澱的碳酸鹽要用水沖已兩次以移除多餘的 CrO42- * ∆ → ppt 為了分離 Sr(NO3)2，硝酸濃度不可低於16M ppt 6-3 + 2~4d HNO3坩鍋 ∆ 冷卻久一點 +5d16 M HNO3 ×2 (乾玻棒刮內壁，移到乾離心管中) 放在冷水中5 min * * BaSO4(s) (white) Sr2+ + 2NO3-→ Sr(NO3)2(s) 2BaCrO4 + H+→ 2Ba2+ + CrO42- + OH- Ba2+ + SO42-→ BaSO4(s) ppt 6-4 + 5~10d H2O + NH3鹼化 + 三乙醇胺 +(NH4)SO4 sol 6-4 + 1 mL H2O + 15M NH3 鹼化 + (NH4)2C2O4 Ca2+ + C2O42-→ CaC2O4(s) SrSO4(s) white CaC2O4(s) (white) Sr2+ + SO4-→ SrSO4(s)

More Related