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寒劍飄雪木蟲 (著名寫手)
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[求助]
雜多酸制備中pH調(diào)節(jié)問題 已有5人參與
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各位蟲友,我想合成一個(gè)單取代的磷鎢酸鹽,文獻(xiàn)上說是將磷鎢酸和相應(yīng)的硝酸鹽溶液水后,緩緩滴加碳酸氫鈉溶液,在不斷攪拌下使其pH值調(diào)為5后停止滴加,繼續(xù)攪拌5h。我照文獻(xiàn)做的時(shí)候把pH值調(diào)到5以后,然后攪拌一會(huì)兒后ph值又降下來了,我應(yīng)不應(yīng)該把pH值又調(diào)回5?還是讓它一直降了?我在問一下,這個(gè)緩緩滴加,到底是緩到什么程度?是我邊攪拌邊滴加上一會(huì)兒后,然后不滴加讓攪拌一會(huì)兒再加呢,還是我一直攪拌滴加至5呢? 忘各位做過此類雜多酸的大師指導(dǎo)指導(dǎo),謝謝了 |
金蟲 (正式寫手)
至尊木蟲 (知名作家)
至尊木蟲 (知名作家)
至尊木蟲 (知名作家)
至尊木蟲 (著名寫手)

木蟲 (著名寫手)
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謝謝你,那我調(diào)到5以后,攪拌了大概有一小時(shí),我測ph值得時(shí)候,大概又降到4了,我調(diào)到5,這樣對(duì)嗎? 還有一個(gè)特別棘手的事,我合成出的單缺位的硅鎢酸鹽極易溶于水,怎么重結(jié)晶了,能給我具體指導(dǎo)一下嗎?文獻(xiàn)表述如下: First PW12 (2.88 g) was dissolved in water (10 mL) and the pH of the solution was adjusted to 4.8 using NaHCO3 solution. This resulted in the formation of lacunary heteropoly anion [PW11O39]7. The solution having pH 4.8 was heated to 90 C with constant stirring. Then to it a solution of Co(NO3)26H2O (0.29 g) in water (10 mL) was added. The NaCoPW11 was obtained by solvent evaporation, and recrystallization from water, followed by subsequent drying at 110 C for 12 h |
木蟲 (著名寫手)
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謝謝老師的指導(dǎo),我是合成的鹽,用的是買來的雜多酸,還有一個(gè)特別棘手的事,我合成出的單缺位的硅鎢酸鹽極易溶于水,怎么重結(jié)晶了,能給我具體指導(dǎo)一下嗎?文獻(xiàn)表述如下: First PW12 (2.88 g) was dissolved in water (10 mL) and the pH of the solution was adjusted to 4.8 using NaHCO3 solution. This resulted in the formation of lacunary heteropoly anion [PW11O39]7. The solution having pH 4.8 was heated to 90 C with constant stirring. Then to it a solution of Co(NO3)26H2O (0.29 g) in water (10 mL) was added. The NaCoPW11 was obtained by solvent evaporation, and recrystallization from water, followed by subsequent drying at 110 C for 12 h |
金蟲 (正式寫手)
木蟲 (著名寫手)
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文獻(xiàn)上說是用熱水重結(jié)晶,選有機(jī)溶劑的話一般選啥好點(diǎn),我看一篇文獻(xiàn)上說是用丙酮,我問一下我合成出的鹽能溶解在丙酮中嗎,合成的產(chǎn)物中有硝酸根、Na和鈷離子,文獻(xiàn)上說是用丙酮萃取,直到丙酮萃取液中無硝酸根,我問問這個(gè)具體怎么操作,是在萃取的時(shí)候,把上層丙酮液吸取完以后,再在丙酮吸取液中加丙酮,直到無硝酸根嗎,這樣做對(duì)嗎,這樣下來是不是得用好多丙酮,丙酮萃取液液好多啊,這么操作呢? 文獻(xiàn)是這么說的 The volume is then reduced to half by evaporation and the heteropolyanion separated in a dense lower layer by liquid-liquid extraction with 80-100 mL of acetone. The extraction is repeated until the acetone extract shows no nitric ions (ferrous sulfate test). The solid sodium salt is obtained as the hydrate (15-20H,O) by evaporation to dryness (in air) of the acetone extracts. |
木蟲 (著名寫手)
木蟲 (著名寫手)
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老師,在給我指導(dǎo)一下重結(jié)晶的問題,我合成出的單缺位的硅鎢酸鹽極易溶于水,怎么重結(jié)晶了,能給我具體指導(dǎo)一下嗎?文獻(xiàn)上說是用熱水重結(jié)晶,也有選有機(jī)溶劑的,我看一篇文獻(xiàn)上說是用丙酮,我問一下我合成出的鹽能溶解在丙酮中嗎,合成的產(chǎn)物中有硝酸根、Na和鈷離子,文獻(xiàn)上說是用丙酮萃取,直到丙酮萃取液中無硝酸根,我問問這個(gè)具體怎么操作,是在萃取的時(shí)候,把上層丙酮液吸取完以后,再在丙酮吸取液中加丙酮,直到無硝酸根嗎,這樣做對(duì)嗎,這樣下來是不是得用好多丙酮,丙酮萃取液液好多啊,這么操作呢? 文獻(xiàn)表述如下: First PW12 (2.88 g) was dissolved in water (10 mL) and the pH of the solution was adjusted to 4.8 using NaHCO3 solution. This resulted in the formation of lacunary heteropoly anion [PW11O39]7. The solution having pH 4.8 was heated to 90 C with constant stirring. Then to it a solution of Co(NO3)26H2O (0.29 g) in water (10 mL) was added. The NaCoPW11 was obtained by solvent evaporation, and recrystallization from water, followed by subsequent drying at 110 C for 12 h |
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