问题 填空题

某化学小组同学,用如图所示实验探究质量守恒定律.

(1)充分反应冷却后,天平不能平衡的是______(填写字母序号).

(2)C实验反应的化学方程式为______.

(3)由上述实验可知,在化学反应前后,一定不变的是______(填数字序号).

①原子种类          ②原子数目          ③分子种类

④分子数目          ⑤元素种类          ⑥物质质量

(4)根据以上实验探究,该同学得知,若用碳酸钠粉末与盐酸反应验证质量守恒定律,从下列装置中,可选择的有______.

(5)由以上探究该同学还清楚了,若将过氧化钠(Na2O2)与水反应,放出能使带火星木条复燃气体,同时生成一种能使酚酞变红的常见物质.则其反应的化学方程式可以写成:______.

答案

(1)实验B在敞开的仪器中进行,锌和稀盐酸反应放出氢气进入空气中,故天平难以平衡;

(2)C实验中,铁与硫酸铜反应生成了铜和硫酸亚铁,反应的方程式是:Fe+CuSO4=FeSO4+Cu;

(3)在化学反应里肯定不变的是:物质的总质量、元素的种类、元素的质量、原子的种类、原子的质量、原子的数目,可以据此选择为①②⑤

(4)若用碳酸钠粉末与盐酸反应验证质量守恒定律,由于碳酸钠粉末与盐酸反应生成二氧化碳,所以必须在密闭的容器中才能够得出正确的结论,满足条件的为c、d、e;

(5)由质量守恒定律可知,若将过氧化钠(Na2O2)与水反应,放出能使带火星木条复燃气体是氧气,同时生成一种能使酚酞变红的常见物质是氢氧化钠,反应的方程式是:2Na2O2+2H2O=4NaOH+O2

故答为:(1)B;(2)Fe+CuSO4=FeSO4+Cu;(3)①②⑤;(4)c、d、e;(5)2Na2O2+2H2O=4NaOH+O2↑.

阅读理解

阅读短文,回答问题。

      Mary is an eight-year-old girl. Every day she washes clothes, looks after her younger sister and

works hard on the farm. Mary wants to go to school, but her mother needs her help at home. So Mary

stays at home instead of going to school.

      Do you want to help Mary? Well, join Save the Children, please! Just 6 yuan a day, you can help a

child like Mary. With your help, children like Mary will be able to have enough food and have chances

to go to school.

     Save the Children is an organization to help poor children like Mary. It has been in service since 1932.

The money from kind people will be used to build schools, hospitals and other necessary buildings.

     If you are a volunteer, there are many wonderful things waiting for you -letters from the children,

their photos and subject reports. Now, if you are interested in the application form, and then you can

donate some money. In this way, you can help a child like Mary!

1. What does Mary do every day?

__________________________________________________________

2. How much money does a person need to donate a week

    if he wants to support a child like Mary?

__________________________________________________________

3. What is "Save the Children"?

__________________________________________________________

4. When did Save the Children begin to work?

__________________________________________________________

5. Why doesn't Mary go to school?

__________________________________________________________

多项选择题