题目内容

【题目】下表是某实验报告中的一组数据：

实验

序号

试剂1

试剂2

混合前

温度/℃

混合后最高或最低温度/℃

①

3.2 mL水

3.2 g Na2CO3固体

20

24.3(t1 )

②

35 mL稀盐酸

3.2 g Na2CO3固体

20

25.1(t2 )

③

35 mL水

2.5 g NaHCO3固体

20

18.5(t3 )

④

35 mL稀盐酸

2.5 g NaHCO3固体

20

16.2(t4)

（1）从实验①、③数据可知：Na2CO3溶于水________热量，NaHCO3溶于水________热量(填“放出”或“吸收”)。

（2）根据t2>t1 可知Na2CO3与稀盐酸反应______热量，根据t4<t3 可知：NaHCO3与稀盐酸反应______热量(填“放出”或“吸收”)。

【答案】（1）放出 吸收 （2）放出 吸收

【解析】

试题分析：（1）从实验①、③数据可知：Na2CO3溶于水溶液温度升高，即Na2CO3溶解时可放出热量。NaHCO3溶于水溶液温度降低，即NaHCO3溶解时可吸收热量。

（2）根据t2>t1 可知Na2CO3与稀盐酸反应放出热量，根据t4<t3 可知：NaHCO3与稀盐酸反应吸收热量。

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