单项选择题：PDC钻头主要由钻头体、（）、喷嘴、保径面和接头等组成。A、切削齿B、牙爪C、牙轮

题型：单项选择题

工业上以粗食盐（含有少量Ca²⁺、Mg²⁺杂质）、氨、石灰石等为原料，可以制备Na₂CO₃．其过程如图1所示．

请回答：

（1）在处理粗盐水的过程中，可加入石灰乳和纯碱作为沉淀剂，则所得滤渣的成分除过量的沉淀剂外还有______．

（2）将CaO投入含有大量的NH₄Cl的母液中，能生成可循环使用的NH₃，该反应的化学方程式是______．

（3）向饱和食盐水中首先通入的气体是______，过程Ⅲ中生成NaHCO₃晶体的反应的化学方程式是______．

（4）碳酸钠晶体失水的能量变化示意图如图2：

Na₂CO₃•H₂O （s）脱水反应的热化学方程式是______．

（5）产品纯碱中常含有NaCl．取a g混合物与足量稀盐酸充分反应，加热、蒸干、灼烧，得b g固体．则该产品中Na₂CO₃的质量分数是______．

（6）熔融Na₂CO₃可作甲烷--空气燃料电池的电解质，该电池负极的反应式是______．

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PDC钻头主要由钻头体、（）、喷嘴、保径面和接头等组成。A、切削齿B、牙爪C、牙轮