问题 实验题

某混合金属粉末,除Fe外,还含有Al、Zn中的一种或两种,含量都在10%以上。某研究小组设计实验探究该混合金属粉末中铝、锌元素的存在,探究过程如下:

【查阅资料】①Zn可以与NaOH溶液反应生成H2

②Zn(OH)2为白色固体,难溶于水,可溶于强碱及NH3·H2O

③Zn2+易形成络合物如[Zn(NH3)4]2+,该络合物遇强酸生成Zn2+、NH4+

【提出假设】假设①:该混合金属粉末中除Fe外还含有Al元素

假设②:该混合金属粉末中除Fe外还含有Zn元素

假设③:该混合金属粉末中除Fe外还含有Al、Zn元素

【实验探究】所用试剂:样品、pH试纸、稀H2SO4、NaOH溶液、稀NH3·H2O。

甲同学基于假设③设计实验方案如下:

乙同学同样基于假设③设计另一实验方案如下:

 

(1)Fe元素在周期表中的位置是第     周期     族。

(2)试剂M是              ;沉淀B是              

(3)你认为甲、乙同学的方案   (填“甲”或“乙”)比较好,理由是           。

(4)操作Ⅰ的主要过程是:在滤液中逐滴加入            ,直至生成的沉淀刚好溶解,再加入足量的               

(5)乙同学将沉淀C洗涤、烘干、冷却后称重,质量为m1g,经计算即可得到样品中铁的质量分数,你认为   (填“是”或“否”)准确,原因是                        

(6)电解法制金属铝的化学方程式是                                       

以Al和NiO(OH)为电极,NaOH溶液为电解液组成一种新型电池,放电时NiO(OH)转化为Ni(OH)2,该电池反应的化学方程式是                                   

答案

(1)第四周期 VIII族(2)NaOH  Al(OH)3 (3)乙 步骤简单,节约药剂。(4)稀硫酸 氨水

(5)不合理,C沉淀为氢氧化铁,经洗涤、烘干、冷却后得到为氧化铁,并非Fe的质量。

(6)2Al2O3(熔融)4Al+3O2↑ (7)Al+3NiO(OH) +H2O+NaOH = 3Ni(OH)2+NaAlO2

题目分析:根据甲同学基于假设③设计实验方案,样品加入酸之后生成了铁盐、铝盐和锌盐,铁盐加过量的强碱生成了沉淀不溶解,而铝盐和锌盐加过量的强碱先生成了沉淀然后沉淀溶解;而铁盐、铝盐加过量的弱碱也生成了沉淀,然后沉淀不溶解,锌盐加过量的弱碱先生成了沉淀然后沉淀溶解,由实验方案可知铁盐、铝盐和锌盐形成的沉淀分三次分离,第一次为:Fe(OH)2,试剂M为NaOH溶液,第二次为:Al(OH)3,铝盐和锌盐加过量的强碱先生成了沉淀,然后沉淀溶解,在滤液中逐滴加入稀硫酸,直至生成的沉淀刚好溶解,又形成了铝盐和锌盐,锌盐加过量的弱碱先生成了沉淀,然后沉淀溶解,铝盐加过量的弱碱也生成了沉淀,然后沉淀不溶解,这样实现了Al(OH)3沉淀的分离;第三次为Zn(OH)2,在滤液中逐滴加入稀硫酸,直至生成的沉淀刚好溶解,再加入适量的NaOH溶液,形成沉淀;(1)铁为第26号元素,故为第四周期 VIII族。(2)根据上述分析可知试剂M是NaOH,沉淀B为Al(OH)3。(3)两同学中乙同学步骤简单,节省药品。(4)操作Ⅰ的主要过程是:在滤液中逐滴加入稀硫酸,直至生成的沉淀刚好溶解,再加入足量的氨水。(5)不合理,C沉淀为氢氧化铁,经洗涤、烘干、冷却后得到为氧化铁,并非Fe的质量。(6)电解铝的反应方程式为2Al2O3(熔融)4Al+3O2↑。(7)电池反应的化学方程式是Al+3NiO(OH) +H2O+NaOH = 3Ni(OH)2+NaAlO2

完形填空

Which part is the most important?

My mother used to ask me what the most important part of the body is. When I was 31  .1 thought music and talking were the most important things, so I said: “My 32 Mommy.”

She said; "No. many people are deaf and can’t hear anything but they live normal lives. But you 33  thinking about my questions and I will ask you again soon. "

Several years passed before she asked me again. This time I told her:“Mommy.  34 is very important to   35  , so it must be our eyes. "

She looked at me and told me: "You are learning fast, but your  36  is not right because there are many people who are blind and who arc happy and healthy all the same.”

Then, last year, my grandpa   37 .

Everybody was crying. My mom asked me: “Do you know the most important body

pan now, my dear? The most important body part is your  38 .”

“Is it because it holds up (支撑)my head?”I asked.

"No, it is because it can hold a head of a friend or a loved one when they 3."

she answered. “ Everybody needs a shoulder to cry on sometime in life. I only hope that you have enough love and friends in your life. So, you will  40 have a shoulder to cry on when you need it."

小题1:A. older           B. younger              C. cleverer

小题2:A. ears                B. eyes                 C. mouth

小题3:A. stop                B. begin                    C. keep

小题4:A. mind                B. heart                    C. sight

小题5:A. everybody           B. somebody         C. nobody

小题6:A. question            B. problem              C. answer

小题7:A. came                B. died                 C. arrived

小题8:A. shoulder            B. foot                 C. hand

小题9:A. laugh               B. dance                    C. cry

小题10:A. never               B. always               C. seldom

判断题