问题 填空题

A、J是日常生活中常见的两种金属,这两种金属和NaOH组成原电池,A作负极;F常温下是气体,各物质有以下的转化关系(部分产物及条件略去).

请回答以下问题:

(1)写出原电池的负极反应方程式______.

(2)常温时pH=12的C溶液中,溶质的阳离子与溶质的阴离子浓度之差为______(写出计算式);相同条件下,等浓度的C溶液与CH3COONa溶液中,C的阴离子与CH3COO-浓度的大小关系:前者______后者(用“>”、“<”或“=”表示).

(3)金属A的氯化物沸点较低,又易升华,能否电解这种熔融氯化物来生产A?______.原因是______.

(4)写出A→J反应的化学方程式______.

(5)由J制备的J(C5H52的结构如图1,其中氢原子的化学环境完全相同.但早期人们却错误地认为它的结构为:

.核磁共振法能够区分这两种结构.在核磁共振氢谱中,正确的结构有______

种峰,错误的结构有______种峰.

(6)含A元素的某盐X常做净水剂,X做焰色反应时,透过钴玻璃观察火焰呈紫色.500mLX的溶液与Ba(OH)2反应生成沉淀的质量

与加入Ba(OH)2物质的量的关系如图2:请回答:X晶体的俗名为______;其溶液的物质量浓度为______mol/L.

答案

:(1)题中H→A为工业冶炼金属铝,A→J为铝热反应,为推断题的突破口,依次可知C→E→H→A→J的转化是中学化学中常见反应,为AlO2-→Al(OH)3→Al2O3→Al→Fe之间的转化,该原电池是铝做负极,铁做正极,电解质溶液为NaOH,可以推知:A为Al,C为NaAlO,E为Al(OH)3,H为Al2O3,J为Fe,M为FeS,原电池中,Al做负极被氧化,在碱性溶液中生成AlO2-,电极反应式为:Al+4OH--3e-=AlO2-+2H2O,故答案为:Al+4OH--3e-=AlO2-+2H2O;

(2)溶液C为NaAlO2,根据溶液呈电中性,即c(AlO2-)+c(OH-)=c(Na+)+c(H+)可知:c(Na+)-c(AlO2-)=c(OH-)-c(H+)=10-2-10-12 mol/L;

故答案为:10-2-10-12 mol/L或c(OH-)-c(H+);

(3)金属A的氯化物为AlCl3,为共价化合物在熔融状态下不导电,

故答案为:否;因为A的氯化物熔沸点低,据此判断它的晶体为分子晶体,在熔融态时不电离,不能被电解;

(4)反应A→J为铝热反应,反应为:Fe2O3+2Al

 高温 
.
 
2Fe+Al2O3 故答案为:Fe2O3+2Al
 高温 
.
 
2Fe+Al2O3

(5)制备的J(C5H52的结构如图1,其中氢原子的化学环境完全相同,核磁共振氢谱中峰值为1,结构为:

结构中含有三种位置的氢原子,所以核磁共振氢谱中峰值为3;故答案为:1;  3

(6)含A元素的某盐X常做净水剂,X做焰色反应时,透过钴玻璃观察火焰呈紫色,说明盐中含有铝元素和钾元素,为明矾,俗称为明矾或白矾;

根据反应计算:

Ba2++SO42-═BaSO4

    1mol   233g

    n     233g

则n=1mol,根据SO42-离子的守恒可知500mLKAl(SO42的溶液中含有溶质的物质的量为0.5mol,

故浓度为:

0.5mol
0.5L
=1mol/L,故答案为:明矾或白矾;1mol/L.

问答题 简答题
阅读理解

阅读理解。

    Naps-short sleeps during the day-may improve memory, experts said recently.

    New research conducted by brain researcher Avi Karni of the University of Haifa in Israel explores

the possibility that naps help lock in sometimes long-term memories. "We still don't know exactly how

memory system works during sleep, but the results of this research suggest it is possible to speed up

memory consolidation (巩固)," Karni said. Long-term memory refers  to memories that stay with us for

years, such as "what" memories-a car accident that happened yesterday-or "how to" memories, such as

one's learned ability to play the pianos.

     Karni, also one of the authors of the study published in a recent issue of the journal Nature

Neuroscience, instructed participants to learn a difficult set of finger games, then divided the study

subjects into two groups: one that napped for an hour, and one that didn't. The people who took an

afternoon snooze showed obvious improvement in their performance by that evening.

     "After a night's sleep the two groups were at the same level, but the group that slept in the afternoon

improved much faster than the group that stayed awake," Karni said. And the study also showed just

how much faster a 90-minute nap could help lock in long-term memories. "Daytime sleep can shorten the

time 'how to' memory weakens and forgetting starts,"Karni said, "Instead of 6 to 8 hours, the brain

consolidated the memory during the 90-minute nap."

1. We can learn from the article that ________.

A. the new research has discovered the memory process during the sleep

B. taking a nap helps improve both long-term and short-term memories

C. Karni's findings are based on comparisons between two groups of participants

D. people who take a nap will never forget "how to" skills once they are learned

2. The underlined word "subjects" in paragraph 3 probably mean________. 

A. the people being tested in the study

B. the people carrying out the study

C. the topics being discussed in the study

D. the areas of knowledge being studied

3. The text is most probably taken from ________.

A. a newspaper report    

B. a library guide 

C. a project handbook    

D. a science site