本方法适用于工业级碳酸锂中质量分数为0.0050%～0.020%的酸不溶物的测定。                                                                                 

2   原理                                                               

试料用盐酸分解，加热煮沸，冷却。过滤，将不溶物烘干，称重。                                                              

3   试剂

3.1盐酸，ρ1.19g/mL。                                                               

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

4   操作步骤                                                                                                                               

4.1试样                                                                       

    碳试样预先在250～260℃烘干2h，置于干燥器中冷却至室温。                                                              

    称取50g试样，精确至0.01g。                                                                 

    独立地进行两次测定，取其平均值。

4.2测定                                                                

4.2.1将试料置于600mL烧杯中，加入200mL水、1滴1g/L甲基橙指示剂，用盐酸中和至试液呈红色并过量1mL，加热煮沸5min，冷却。

4.2.2用已恒重的4号玻璃滤埚过滤，以热水洗涤烧杯3～4次、滤渣7～8次，于105～110℃烘干1h，称至恒重。

5   结果计算                                                                                                                           

   按下式计算酸不溶物的含量，以质量分数表示：

 式中：m₁—玻璃滤埚和不溶物的质量，g；                                                                

m

m—试料的质量，g。                                                                                                                                 

6   允许差                                                           

  两个测定值之间的差值应不大于下表所列允许差。

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7   参考文献

[1] 国家标准GB/T 11064.11-89