问题 实验题

现用质量分数为98%、密度为1.84 g·cm-3的浓硫酸来配制500 mL、0.2 mol·L-1的稀硫酸。可供选择的仪器有:①玻璃棒 ②烧瓶 ③烧杯 ④胶头滴管 ⑤量筒 ⑥容量瓶 ⑦托盘天平 ⑧药匙。

请回答下列问题:

(1)上述仪器中,在配制稀硫酸时用不到的有         (填代号)。

(2)经计算,需浓硫酸的体积为           

现有①10 mL  ②50 mL  ③100 mL三种规格的量筒,你选用的量筒是         。(填代号)

(3)将浓硫酸加适量蒸馏水稀释后,冷却片刻,随后全部转移到          mL的容量瓶中,转移时应用玻璃棒         。转移完毕,用少量蒸馏水洗涤烧杯和       2~3次,并将洗涤液全部转移到容量瓶中,再加适量蒸馏水,振荡容量瓶,使溶液混合均匀。然后缓缓地把蒸馏水直接注入容量瓶直到液面接近瓶颈刻度        cm处,改用         滴加蒸馏水到           与刻度线相切。塞上瓶塞、摇匀后,把溶液倒入试剂瓶、贴上标签。

(4)在配制过程中,其他操作都准确,下列操作中,能引起误差偏高的有            (填代号)。

①转移前,容量瓶中含有少量蒸馏水

②定容时,加蒸馏水超过标线,又用胶头滴管吸出

③定容时,俯视刻度线

④定容摇匀后,发现液面低于标线,又用胶头滴管加蒸馏水至标线

答案

(1) ②⑦⑧ (2)  5.4mL  ;   ①   

(3)500 mL;引流  ;玻璃棒;1-2cm;胶头滴管; 凹液面的最低点   (4)③ 

题目分析:(1)配制稀硫酸时,用量筒量取浓硫酸,在烧杯中稀释,所以用不到的是烧瓶、托盘天平和钥匙,答案选②⑦⑧。

(2)由于在稀释过程中溶质是不变的,所以需要浓硫酸的体积是。量筒的规格和5.4ml最为接近,误差越小,所以应该选择的量筒是10ml,答案选①。

(3)将浓硫酸加适量蒸馏水稀释后,冷却片刻,随后全部转移到500mL的容量瓶中,转移时应用玻璃棒引流。转移完毕,用少量蒸馏水洗涤烧杯和玻璃棒2~3次,并将洗涤液全部转移到容量瓶中,再加适量蒸馏水,振荡容量瓶,使溶液混合均匀。然后缓缓地把蒸馏水直接注入容量瓶直到液面接近瓶颈刻度1~2cm处,改用胶头滴管滴加蒸馏水到凹液面的最低点与刻度线相切。塞上瓶塞、摇匀后,把溶液倒入试剂瓶、贴上标签。

(4)根据可知,转移前,容量瓶中含有少量蒸馏水,则不会影响硫酸的浓度;定容时,加蒸馏水超过标线,又用胶头滴管吸出,则会导致溶质减少,所以浓度偏低;定容时,俯视刻度线,则容量瓶中溶液的体积偏少,则浓度偏高;定容摇匀后,发现液面低于标线,又用胶头滴管加蒸馏水至标线,则容量瓶中溶液的体积增加,则浓度偏低,答案选③。

点评:该题是高考中的常见题型,属于中等难度的试题。试题综合性强,在注重对基础知识巩固和训练的同时,侧重对学生能力的培养和解题方法的指导与训练,有利于培养学生规范严谨的实验设计能力以及评价能力。该类试题主要是以常见仪器的选用、实验基本操作为中心,通过是什么、为什么和怎样做重点考查实验基本操作的规范性和准确性及灵活运用知识解决实际问题的能力。

阅读理解

阅读理解

     Sixteen years ago, Eileen Doyle's husband, an engineer, took his four children up for an early morning

cup of tea, packed a small case and was never seen or heard of again.Eileen was astonished and in a

state of despair.They had been a happy family and, as far as she knew, there had been nothing wrong with their marriage.

       Every day of the year a small group of men and women quietly pack a few belongings and without so much as a note or a goodbye close the front door for the last time, leaving their debts, their worries and

their confused families behind them.Last year, more than 1,200 men and nearly as many women were

reported missing from home-the highest in 15 years.Many did return home within a year, but others

rejected the past completely and are now living a new life somewhere under a different identity.

      To those left behind, this form of desertion (遗弃) is a terrible blow to their pride and selfconfidence.

Even the finality of death might be preferable.At least it does not imply rejection or failure.Worse than that, people can be left with an unfinished marriage, not knowing whether they will have to wait several years

before they are free to start a fresh life.

      Clinical psychologist Paul Brown believes most departures of this kind to be well planned rather than

impulsive."It's typical of the kind of personality which seems able to ignore other people's pain and

difficulties.Running away, like killing yourself, is a highly aggressive act.By creating an absence the people

left behind feel guilty, upset and empty."

1. When her husband left home, Eileen Doyle ________.

A. could not forgive him for taking the children

B. had been expecting it to happen for some time

C. could not understand why

D. blamed herself for what had happened

2. Most people who leave their families behind them ________.

A. do so without warning

B. do so because of their debts

C. come back immediately

D. change their names

3. Which might be the title of the passage?

A. Broken marriage

B. New life after desertion

C. A new social problem

D. Desertion and its influence

4. What can be inferred from the passage?

A. Many people choose to leave home quietly because they hate their family.

B. Paul Brown regards leaving home as an act of selfishness.

C. Those who are left behind will lose confidence and won't marry again.

D. Eileen's husband, together with his four kids, was probably killed in an accident.

单项选择题