问题 问答题

短周期中的A、B、C、D、E 5种元素,原子序数依次增大,A、D同主族;A、B的原子序数之和等于C的原子序数;C2-离子与D+离子的核外电子数相等;B原子与D+离子的核外电子数之和等于E原子的核外电子数,且D、E两元素能形成微粒个数比为1:1的离子化合物.

(1)由A、C、E 三种元素组成的一种化合物常用作消毒液其名称为______.

(2)D、E元素可组成化合物甲,用石墨为电极电解甲的水溶液时,阳极的电极反应式为______;阴极区溶液的pH______.

(3)A、C元素可组成原子个数比为1:1的共价化合物乙,将E单质通入乙的水溶液中,生成一种强酸,并有气体放出,反应的化学方程式为______.

(4)A、B、C、D、E中的任意三种元素可组成多种化合物,X和Y是其中的两种.X和Y都是既含离子键又含共价键的离子化合物;将X、Y分别溶于水时,X能促进水的电离,而Y能抑制水的电离,X水溶液的pH<7,Y水溶液的pH>7.将0.2mol•L-1的X溶液与0.1mol•L-1的Y溶液等体积混合后,溶液呈碱性.请判断:

①X的化学式为______,Y的化学式为______.

②混合溶液中各种带电微粒的物质的量浓度由大到小的顺序为______.

答案

C2-离子与D+离子的核外电子数相等,由电荷可知C为ⅥA族元素,D为ⅠA族元素,A、D同主族,则A可为H元素,D为Na元素,C为O元素,A、B的原子序数之和等于C的原子序数,则B为N元素,B原子与D+离子的核外电子数之和等于E原子的核外电子数,E的核外电子数为7+10=17,则E的原子序数为17,E为Cl元素,

(1)由H、O、Cl三种元素组成的一种化合物常用作消毒液,应为HClO,名称为次氯酸,故答案为:次氯酸;

(2)电解NaCl溶液,阳极反应式为2Cl--2e-=Cl2↑,阴极反应式为2H2O+2e-=H2↑+2OH-,阴极生成OH-,则pH增大,大于7,

故答案为:2Cl--2e-=Cl2↑;大于7;

(3)A、C元素可组成原子个数比为1:1的共价化合物为H2O2,与Cl2发生氧化还原反应,生成的强酸为HCl,气体为O2,反应的化学方程式为Cl2+H2O2=2HCl+O2↑,

故答案为:Cl2+H2O2=2HCl+O2↑;

(4)①X能促进水的电离,X水溶液的pH<7,说明水解呈酸性,应为铵盐,可能为NH4Cl(或NH4NO3),Y能抑制水的电离,Y水溶液的pH>7,抑制水的电离,应为碱,可为NaOH,

故答案为:NH4Cl(或NH4NO3);NaOH;

②将0.2mol•L-1的NH4Cl(或NH4NO3)溶液与0.1mol•L-1的NaOH溶液等体积混合后,反应后溶液中存在NH4+和NH3•H2O,

离子浓度大小顺序为c(Cl-)>c(NH4+)>c(Na+)>c(OH-)>c(H+)[或c(NO3-)>c(NH4+)>c(Na+)>c(OH-)>c(H+)],

故答案为:c(Cl-)>c(NH4+)>c(Na+)>c(OH-)>c(H+)[或c(NO3-)>c(NH4+)>c(Na+)>c(OH-)>c(H+)].

单项选择题
阅读理解

阅读理解。

     More teachers are starting off the school year with letters to parents and students to introduce themselves

and set a tone (基调)for the year. The letters are a good way to start positive communication with parents,

several teachers told Education World.

     "I think it's professional (专业的)," said Dorothy Peselli, an English teacher at Sparta

High School in Sparta, New Jersay, Peselli, who gives out the letters the first day of school,

told Education World."It gives parents an image of you as a professional. If you start

communication off in a positive manner, you will have the parents on your side when you need them."

     In her letter to parents, Peselli encourages them to call or e-mail her with specific concerns about their

children."I want to work as a team to make sure that your child becomes an independent lifelong learner,"

Peselli wrote to parents last September. She also telephones the parents of all her students at the beginning of

the year.

     Peselli includes with the letter a classroom handbook (手册) listing plans and rules. And she requires that

both parents and students read and sign statements (included in the letter!) that they read the handbook. The

student letter also lists needed supplies and gives encouragement."Please come to class ready to work and learn.

This will be an exciting year for all of us," it  says.

      Last year, Peselli taught at a different high school and parents there were"shocked", but appreciative, that

she had so much contact with them,"I received roses and a thank-you note from one boy and his mother".

Peselli said. She wished her own children's teachers would take the time to write notes as well."I never got a

letter home from any of my daughter's high school teachers." She said. "It would be nice to know the

background of some of the people who are teaching my daughter."

1. We may learn from the text that ____.

A. most teachers are writing letters to parents and students

B. the handbook is used to list supplies and give encouragement

C. Peselli believe it important for teachers to exchange information with parents

D. Peselli mainly introduces her background and teaching experiences in the letters

2. The underlined word"it" in the fourth paragraph refers to _____. 

A. the handbook B. the requirement C. the school D. the letter

3. We can infer from the last paragraph that _____.

A. parents were satisfied with Peselli's way of working

B. Peselli means to surprise parents by writing students

C.Peselli seemed to be popular among boy students

D. all Peselli's children are studying in high schools

4. The purpose of the text is to _____.

A. introduce an English teaching method

B. give advice on how to teach students

C. encourage teachers to keep in touch with parents

D. show us how Dorothy Peselli makes teaching plans