问题 填空题

如图为实验室某浓盐酸试剂瓶标签上的有关数据,试根据标签上的有关数据回答下列问题:

(1)该浓盐酸中HCl的物质的量浓度为__________mol·L-1

(2)取用任意体积的该盐酸溶液时,下列物理量中不随所取体积的多少而变化的是_______。

A.溶液中HCl的物质的量      B.溶液的浓度

C.溶液中Cl-的数目           D.溶液的密度

(3)在容量瓶的使用方法中,下列操作不正确的是____________

A.使用容量瓶前检验是否漏水

B.容量瓶用水洗净后,再用待配溶液洗涤

C.配制溶液时,如果试样是固体,把称好的固体用纸条小心倒入容量瓶中,缓慢加水至接近刻度线1~2cm处,用胶头滴管加蒸馏水至刻度线。

D.配制溶液时,若试样是液体,用量筒取样后用玻璃棒引流倒入容量瓶中,缓慢加水至刻度线1~2cm处,用胶头滴管加蒸馏水至刻度线。

E.盖好瓶塞,用食指顶住瓶塞,另一只手托住瓶底,把容量瓶反复倒转多次,摇匀。

(4)某学生欲用上述浓盐酸和蒸馏水配制500 mL物质的量浓度为0.400 mol·L-1的稀盐酸。

①该学生需要量取________mL上述浓盐酸进行配制。(保留小数点后1位)

②在配制过程中,下列实验操作对所配制的稀盐酸的物质的量浓度有何影响?(在括号内填“偏大”、“偏小”或“无影响”)。

a.用量筒量取浓盐酸时俯视观察凹液面。(  )

b.定容后经振荡、摇匀、静置,发现液面下降,再加适量的蒸馏水。(  )

(5)①假设该同学成功配制了0.400 mol·L-1的盐酸,他又用该盐酸中和含0.4 g NaOH的NaOH溶液,则该同学需取________mL盐酸。

②假设该同学用新配制的盐酸中和含0.4 g NaOH的NaOH溶液,发现比①中所求体积偏小,则可能的原因是________。

A.浓盐酸挥发,浓度不足            B.配制溶液时,未洗涤烧杯

C.配制溶液时,俯视容量瓶刻度线    D.加水时超过刻度线,用胶头滴管吸出

答案

(1)11.9 (2分)  (2)BD (2分)   (3)   B、C、D(2分,)

(4)①16.8(2分) ②a.偏小(2分) b.偏小(2分)

(5)①25(2分) ②C(2分)

题目分析:(1)设盐酸体积为1L,c(HCl)=1L×1000×1.19g/L×36.5%÷36.5g/mol÷1L=11.9mol•L‾1

(2)溶液中HCl的物质的量、溶液中Cl-的数目随所取体积的多少而变化,溶液的浓度、溶液的密度不随所取体积的多少而变化,故正确答案为BD。

(3)A、使用容量瓶前要检验是否漏水,正确;B、容量瓶不需要润洗,错误;C、称量的溶质应在烧杯中溶解,冷却后再转移至容量瓶中,错误;D、量取的液体也要在烧杯中溶解,错误;E、定容后,,盖好瓶塞,用食指顶住瓶塞,另一只手托住瓶底,把容量瓶反复倒转多次,摇匀,正确。

(4)①设需要的浓盐酸的体积为VL,则0.5L×0.400mol•L‾1=V×11.9mol•L‾1,可得V=0.0168L=16.8mL。

②a用量筒量取浓盐酸时俯视观察凹液面,造成所取浓盐酸的体积偏小,故配制的稀盐酸浓度偏小;b定容后经振荡、摇匀、静置,发现液面下降,再加适量的蒸馏水,造成溶液的体积偏大,故配制的稀盐酸浓度偏小。

(5)①HCl与NaOH反应,物质的量之比为1:1,所以V(HCl)=0.4g÷40g/mol÷0.400mol•L‾1=0.025L=25mL。

②所以盐酸体积偏小,说明配制的盐酸浓度偏大。A、浓盐酸挥发,造成配制的盐酸浓度偏小,不符合要求;B、配制溶液时,未洗涤烧杯,造成配制的盐酸浓度偏小,不符合要求;C、配制溶液时,俯视容量瓶刻度线,造成配制的溶液体积偏小,浓度偏大,正确;D、加水时超过刻度线,用胶头滴管吸出,造成配制的溶液体积偏大,浓度偏小,不符合题意。

单项选择题
问答题

Have you had a headache during a test Have you ever been so worried about something that you have a headache or even can’t sleep at night If so, then you know what stress is. Stress is what you feel when you are worried about something. This worry in your mind can make your body feel bad. You may feel angry, sad, scared, or afraid—all of which can give you a stomachache or a headache.
However, there are different kinds of stress. Some kinds of stress are good and others are bad. Good stress might happen when you’re called to answer questions in class or when you have to give a speech. This kind of stress can help you to get things better done. For example, you may do a better job on your test if the stress pushes you to prepare better before the test.
On the other hand, bad stress can happen if stress lasts too long. You may not feel well if your parents are fighting, if a family member is sick, if you’re having problems at school, or if anything else makes you unhappy every day. That kind of stress isn’t going to help you. And it can actually make you sick.
The best way to fight stress is to have a balanced life. Make sure you keep your SELF in mind: Sleep, Exercise, Leisure(休闲), and Food. If you get enough sleep and eat properly, and if you exercise and leave time for fun, you’ll probably feel less stressed.

Title: Face the Stress
Meaning of stressStress is a (68) when you are worried about something.
Possible effectYou may feel uncomfortable in your (69) and body.

Good stress

· It might happen when you have to (70) in public.

· It will be more (71) for you to do the job successfully.

· It makes you (72) better before doing the job.

Different kindsBad stress

· It might happen if your stress (73) too long.

· You may not feel well with the (74) of a family member, problems at school or something else that worries you every day.

· It might stop you from getting your work well done.

How to keep stress (75) 

Have a balanced life.

· Have enough sleep and have (76) food.

· Take exercise and have time to (77) yourself.