题目

You may have heard adults say they are uncomfortable in the morning without a cup of coffee. One reason they may feel that way is that coffee contains caffeine(咖啡因). Caffeine appears naturally in coffee, tea, and cocoa beans, which are used to make chocolate. But now food makers are adding it to many products, from potato chips to water. The US government is especially worried about the problem. That’s why the Food and Drug Administration (FDA) is studying the health effects of caffeine on young people. Studies show that too much caffeine can make people nervous and unable to sl 溴主要以Br-形式存在于海水中，海水呈弱碱性。工业上制备的Br2的操作步骤为： ①一定条件下，将Cl2通入浓缩的海水中，生成Br2 ②利用热空气将Br2吹出，并用浓Na2CO3溶液吸收，生成NaBr、NaBrO3等 ③用硫酸酸化步骤②得到的混合物 完成下列填空： 27.Cl2氧化Br-应在         条件下进行，目的是为了避免         28.Br2可用热空气吹出，其原因是             29.写出步骤③所发生的化学反应方程式。 用硫酸而不用盐酸酸化的原因可能是              。步骤②的产品有时运输到目的地后再酸化，主要是因为         30.为了除去工业Br2中微量的Cl2,可向工业Br2中     a.通入HBr   b.加入Na2CO3溶液    c.加入NaBr溶液  d.加入Na2SO3溶液