问题 问答题

已知氨水的电离度与醋酸的电离度在同温同浓度下相等,溶有一定量氨的氯化铵溶液呈碱性.现向少量的Mg(OH)2悬浊液中,加入适量的饱和氯化铵溶液,固体完全溶解.

甲同学的解释是.Mg(OH)2(固)⇌Mg2++2OH-…①

NH4++H2O⇌NH3•H2O+H+…②H++OH-=H2O…③

由于NH4+水解显酸性,H+与OH-反应生成水,导致反应①平衡右移,沉淀溶解;

乙同学的解释是.Mg(OH)2(固)⇌Mg2++2OH-…①NH4++OH-⇌NH3•H2O…②

由于NH4Cl电离出的NH4+与Mg(OH)2电离出的OH-结合,生成了弱的电解质NH3•H2O,导致反应①的平衡右移,Mg(OH)2沉淀溶解.

(1)丙同学不能肯定哪位同学的解释合理,于是选用下列的一种试剂,来证明甲、乙两位同学的解释只有一种正确,他选用的试剂是______(填写编号).

A.NH4NO3B.CH3COONH4C.Na2CO3D.NH3•H2O

(2)请你说明丙同学作出该选择的理由______

(3)丙同学将所选试剂滴入Mg(OH)2的浊液中,Mg(OH)2溶解;由此推知,甲和乙哪位同学的解释更合理______(填“甲”或“乙”);完成NH4Cl饱和溶液使Mg(OH)2悬浊溶解的离子方程式______.

答案

(1)硝酸铵和氯化铵相似,只有铵根离子的水解,而碳酸钠和氨水溶液都呈碱性,注意B符合,

故答案为:B;

(2)醋酸铵溶液呈中性,可证明是否由于铵根离子水解呈酸性的原因导致氢氧化镁溶解,

故答案为:醋酸铵溶液显中性;

(3)将所选试剂滴入Mg(OH)2的浊液中,Mg(OH)2溶解,可说明乙同学的解释正确,

则NH4Cl饱和溶液使Mg(OH)2悬浊溶解的离子方程式为2NH4++Mg(OH)2=2NH3•H2O+Mg2+

故答案为:氯化铵溶液乙;2NH4++Mg(OH)2=2NH3•H2O+Mg2+

填空题
阅读理解

阅读理解。

     There are a number of special days of the year that are celebrated in different countries. The origins of most

of the days are unknown. They were certainly not created by individual people. Other days, however, especially

those celebrated in western countries, often owe their origins to a particular person. One of the most popular of

these, even though it is fairly recent, is Mother's Day. Mothers have always been highly regarded in all cultures.

The ancient Romans had a festival known as Hilaria, during which children took presents to the temple of the

"Mother of the Gods". The Christian Church adopted this idea and called it Mothering Sunday. However, over

the years this custom was gradually forgotten and almost disappeared by the end of the 19th century.

     Born in 1864 in Virginia, USA, Anna Jarvis was a school teacher and believed children should show gratitude

to their mothers for all their love and care. Encouraged by a friend, she wrote to thousands of important people-

politicians, churchmen, doctors, city officials-and asked them to support her idea: a special day of the year for

thanking mothers.

     In 1910 the Governor of West Virginia introduced Mother's Day into the state. The date chosen was May

10-the second Sunday in May, which is still observed in America today. This date was chosen because May 10

was the date on which in 1908 Anna Jarvis's mother had died. In 1914 President Woodrow Wilson made May

10 the official date for Mother's Day throughout the United States.

     Soon there was a Mother's Day International Association and the custom began to be adopted in many

countries of the world.

     Anna Jarvis, a sad and disillusioned woman, died in 1948. The custom she had worked so hard to establish

and which had become almost universal had lost its original purpose. It had been taken over by business. As

with Christmas, the giving of presents and the sending of cards had become a multi-million-dollar industry.

1. The story is about _____.

A. Mothering Sunday for Christmas

B. the origin of a special day for mothers

C. President Wilson and Anna Jarvis

D. how people celebrate Mother's Day

2. Hilaria was a festival in _____.

A. ancient Rome

B. America

C. China

D. the Christian Church

3. Anna Jarvis wanted to _____.

A. thank her mother for her care

B. introduce a celebration for mothers

C. meet thousands of important people

D. make her pupils celebrate her on Mother's Day

4. May 10 became the date for Mother's Day because _____.

A. May is in the American spring

B. it was the second Sunday in May in 1910

C. President Wilson liked the date

D. this was the date that Anna Jarvis's mother died

5. Unfortunately, Anna Jarvis was not happy with Mother's Day when she died because _____.

A. her mother was not there to see it

B. she had never been a mother herself

C. people were too interested in making it a business

D. no one gave any presents or cards to their mothers