问题 实验题

如右图所示,把试管放入盛有25 ℃饱和澄清石灰水的烧杯中,试管中开始放入几小块镁片,再用滴管滴入10 mL盐酸于试管中,试回答下列问题:

(1)实验中观察到的现象是________________________________ 。

(2)产生上述现象的原因是____________________________。

(3)写出有关反应的离子方程式:_________________________________;

反应中转移了0. 04mol电子时;标准状况下产生多少________mL的H2;消耗镁多少________g(保留两位小数);生成的MgCl2物质的量浓度为________。(溶液体积保持不变)

(4)由实验推知,镁片溶液和盐酸的总能量________(填“大于”、“小于”或“等于”) MgCl2和H2的总能量;此反应为________ (填放热反应或者吸热反应)。

答案

(1)①镁片上有大量气泡产生;②镁片逐渐溶解;③烧杯中溶液变浑浊

(2)镁与盐酸反应产生氢气,该反应为放热反应,Ca(OH)2在水中的溶解度随温度升高而减小,故析出Ca(OH)2晶体

(3)Mg+2H===Mg2+H2↑;448;0.48;2.0mol/L

(4)大于;放热反应

题目分析:镁是活泼金属,能与稀盐酸发生反应,在镁片上产生大量气泡,即产生氢气,随着反应的进行,镁片逐渐溶解,该反应放出大量的热,而饱和石灰水随着温度的升高,溶解度逐渐减小,逐渐有Ca(OH)2晶析析出,所以烧杯中溶液变浑浊。该反应的离子的方程式为Mg+2H===Mg2+H2

反应中转移了0. 04mol电子时,即生成0.02molH2,标准状况下产生448mL的H2;消耗镁0.02molMg,即消耗镁:g;生成的MgCl2物质的量浓度为

由实验可知,该反应为放热反应,反应物的总能量大于生成物的总能量,所以镁片溶液和盐酸的总能量大于MgCl2和H2的总能量。

点评:本题考查化学实验基础知识,还结合了化学反应能量的变化,判断放热反应的依据,侧重考查学生基础知识的掌握和分析问题,解决问题的能力,解题的关键是学生要学会联系和运用已学知识,逻辑推理,从而找到解题的突破口。

阅读理解

阅读理解。

     You may know your mother, but how well do you really know Mother's Day? Cards, flowers, sales,

TV specials, and a day off for someone who really deserves it -those are what probably come to mind

for many people when they think of Mother's Day. But there's more to the story.

    The earliest Mother's Day celebrations were held during spring in ancient Greece. The celebrations

honored Rhea, the Mother of the gods. During the 1600's, England celebrated a day called Mothering

Sunday. On this day even servants were given the day off to spend with their families. A mothering cake

was even served with the family meal.

     In the US, Mother's Day began in 1872 when Julia Ward Howe, who wrote the words to the famous

song The Battle Hymn of the Republic, suggested it as a day devoted to peace. But it didn't really become popular until 1907 when Anna Jarvis stared a campaign to honor mothers. She believed that mothers

could help people get over the pain they experienced during the Civil

     War. The US isn't alone in devoting a day to mothers. Many other countries including Denmark,

Finland, Italy, Turkey, Australia, Japan, and Belgium also honor their mothers in May. Other countries

honor their mothers at different times of the year.

     Learning more about Mother's Day and celebrating Mother's Day are important, but probably not as

important as understanding what your own mother, or grandmother, or aunt has really done for you. And

that will certainly be appreciated more than one day in a year.

1. What is the passage mainly about?

A. The reason why people celebrate Mother's Day.

B. The ways people honor mothers.

C. The history of Mother's Day.   

D. The great contribution of mothers.

2.  Where was the earliest Mother's Day celebrated?

A. In ancient Greece.

B. In the US.

C. In England.

D. In Italy.

3. We can learn from the passage that _____.

A. Rhea is the mother of a king in ancient Greece

B. not all the countries celebrate Mother's Day in May

C. only mothers were given a day off on Mothering Sunday

D. it was in 1872 that Mother's Day really came into being

4. The last paragraph tells us that _____.

A. all the people should celebrate Mother's Day

B. only mothers are honored on Mother's Day

C. understanding mothers' work is more important than just celebrating Mother's Day

D. people should celebrate Mother's Day every day

问答题 简答题