本方法適用于工業(yè)級碳酸鋰中質量分數為0.0050%～0.020%的酸不溶物的測定。                                                                                 

2   原理                                                               

試料用鹽酸分解，加熱煮沸，冷卻。過濾，將不溶物烘干，稱重。                                                              

3   試劑

3.1鹽酸，ρ1.19g/mL。                                                               

3.2甲基橙指示劑，1g/L。                                                              

4   操作步驟                                                                                                                               

4.1試樣                                                                       

    碳試樣預先在250～260℃烘干2h，置于干燥器中冷卻至室溫。                                                              

    稱取50g試樣，精確至0.01g。                                                                 

    獨立地進行兩次測定，取其平均值。

4.2測定                                                                

4.2.1將試料置于600mL燒杯中，加入200mL水、1滴1g/L甲基橙指示劑，用鹽酸中和至試液呈紅色并過量1mL，加熱煮沸5min，冷卻。

4.2.2用已恒重的4號玻璃濾堝過濾，以熱水洗滌燒杯3～4次、濾渣7～8次，于105～110℃烘干1h，稱至恒重。

5   結果計算                                                                                                                           

   按下式計算酸不溶物的含量，以質量分數表示：

 式中：m₁—玻璃濾堝和不溶物的質量，g；                                                                

m

m—試料的質量，g。                                                                                                                                 

6   允許差                                                           

  兩個測定值之間的差值應不大于下表所列允許差。

                                                                     ％

7   參考文獻

[1] 國家標準GB/T 11064.11-89