问题 计算题

在标准状况下进行甲、乙、丙三组实验,三组各取30mL同浓度的盐酸溶液,加入同一种镁铝合金粉末,产生气体,有关数据列表如下

(1)甲组实验中,盐酸__________(填“过量”“适量”或“不足量”),乙组实验中,盐酸_________(填“过量”“适量”或“不足量”)。参考合适的数据计算出盐酸的物质的量浓度为_____________。

(2)参考合适的数据组合求得的Mg、Al的物质的量之比为____________。

(3)在丙组实验之后,向容器中加入1mol·L-1的氢氧化钠溶液,能使合金中的铝恰好溶解,不形成含铝的沉淀,并使Mg2+刚好沉淀完全,再过滤出不溶固体,求滤液中各溶质的物质的量和所加入氢氧化钠溶液的体积(写计算过程)。

答案

(1)过量; 不足量; 1mol·L-1

(2)1∶1

(3)滤液中溶质为NaCl,NaAlO2

设丙组中Mg、Al的物质的量均为x。

则24x+27x=0.459,x=0.009mol

根据Cl元素守恒:n(NaCl)=n(HCl)=1×0.03=0.03mol

根据Al元素守恒:n(NaAlO2)=n(Al)=0.009mol

由Na元素守恒:n(NaOH)=n(NaCl)+n(NaAlO2)=0.03+0.009=0.039mol

V(NaOH)==0.039L=39mL

阅读理解

阅读理解。

    Taiwanese singer Stefanie Sun (孙燕姿) looks just like any other young girl. She has short hair, a clear

face and a sweet smile. However, there is something about her that makes her very special: her voice. No

one else can sing like her. Now, Sun is a bright star. She has released many albums (专辑).

     Sun was born in Singapore. When she was a child, her father told her: "A person should always be good

at something in life, so they have something to do for a hobby." Sun chose to learn to play the piano when

she was only five. Then, she took up kick-boxing (搏击操) because she felt she was thin and wanted to

make herself stronger.

     She often sings about the pain and happiness of growing up. The simple but true feelings in her music

are loved by teens. "Sun may be a star, but she seems like a normal girl. She is close to us," said Zhu Liying,

15, a Beijing student. "Her songs give me courage." 

    Eventually, the star was tired because she had worked so hard. She stopped singing for a while and had

a one-year holiday to travel. "I won't give up singing. I just want a rest and to try something new. I hope to

make better music when I come back," Sun said then.

    Now she is working hard again to let her fans hear more beautiful music.

1. Which is NOT true about Sun? [ ]

A. She has short hair.

B. She always has sweet smiles.

C. Her face looks clear.

D. She is a very famous actress.

2. The underlined word "released" in the first paragraph means ______. [ ]

A. made sth. public

B. set free

C. let out

D. made up of

3. Sun learned kick-boxing when she was still a child because ______.[ ]

A. she wanted to be a dancer

B. she wanted to get stronger

C. she enjoyed dancing

D. she wanted to be famous

4. Teenagers love Sun's songs because ______. [ ]

A. her songs are about the pain of growing up

B. she looks clear and is kind to all her fans

C. the feelings in her songs are simple but true

D. her songs are about love and friends

单项选择题