题目

The size and location of the world’s deserts are always changing. Over millions of years, as climates change and mountains rise, new dry and wet areas appear. But within the last hundred years deserts have been increasing after frightful speed. This is partly because of natural changes, but most responsible for creating deserts are men.     Man can make deserts, but they can also prevent them from getting bigger. Algeria is planning a green belt of trees along the edge of the Sahara Desert to stop the sand. In China, too, windbreaks are being built in the northwest to keep the des 已知NaHCO3的溶解度较小。在NH3和NaCl均达到饱和状态的混合溶液中通入CO2，可析出NaHCO3固体： NaCl＋NH3＋CO2＋H2O===NaHCO3↓＋NH4Cl 据此，我国杰出的化学家侯德榜博士设计出了生产纯碱的方法： ―→ 这被人们称为侯氏制碱法。 试回答下列问题： (1)写出由NaHCO3制取Na2CO3的化学方程式：__________________________________ ___________________________________________________________________________。 (2)某课外活动小组，接受实验室的任务，用Na2CO3制取NaOH，提供的原料只有纯碱和石灰石。请将你的实验方法用流程图表示出来： __________________________________________________________。