试题与答案

(12分)(1)某化学小组的同学在学习了NaHCO3和Na2CO3的有关知识后,

题型:实验题

题目:

(12分)(1)某化学小组的同学在学习了NaHCO3和Na2CO3的有关知识后,进行如下实验:在两支试管中分别加入3mL4 mol·L1稀盐酸,将两个各装有0.3g NaHCO3或 Na2CO3粉末的小气球分别套在两支试管口。将气球内的NaHCO3或Na2CO3同时倒入试管中,观察到现象如下:

①试管中(填产生沉淀或气体及反应速率等相关现象)___________              _。

②盛______________的试管中气球变得更大,大小气球体积之比约为(填简单整数比)____________;

③甲同学用手触摸试管,发现盛NaHCO3粉末的试管变冷,而盛Na2CO3

的试管温度有升高。由此他得出:不管其状态如何,NaHCO3和HCl反应为吸热反应,而Na2CO3和HCl反应为放热反应。类似如中和热,甲同学写出了下列热化学方程式:

HCO3(aq)+H+(aq)=H2O(l)+CO2(g); △H>0

CO32(aq)+2H+(aq)=H2O(l)+CO2(g); △H<0

甲下结论的方法是否正确____________(填“正确”或“不正确”)

(2)为研究是吸热还是放热反应,继续进行了下列实验(每次实验各做3次平行实验,取平均值):

序号试剂1试剂2混合前温度混合后最高或最低温度
35mL水2.5g NaHCO3固体20℃18.5℃
35mL水3.2g Na2CO3固体20℃24.3℃
35mL

稀盐酸

含2.5g NaHCO3的饱和溶液32.5mL20℃19℃
 35mL

稀盐酸

含3.2g Na2CO3的饱和溶液23.1 mL+10ml水20℃24.2℃
 35mL

稀盐酸

2.5gNaHCO3固体20℃16.2℃
 35mL

稀盐酸

3.2g Na2CO3固体20℃25.1℃
请你帮助填写相关内容:

①该研究报告的题目是《_____________________________________》;

②该实验中所用的仪器除试管、药匙(或V型纸槽)、气球、玻璃棒、烧杯、量筒、保温瓶外,还需要的仪器名称为_________和__________;通过上述实验可得出五条结论(用“吸热”或“放热”填写):

a:NaHCO3的溶解是_______过程;

b:Na2CO3的溶解是_______过程;

c:NaHCO3的饱和溶液和盐酸的反应是____________反应;

d:Na2CO3的饱和溶液和盐酸的反应是____________反应;

e:NaHCO3固体与稀盐酸反应的反应热是______(填a、b、c、d中的字母)的热效应之和。

答案:

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Last Sunday I saw a worst storm in years. It came sudden and went on for the suddenlyover three hours. After lunch, I went into my room to have a r...

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