问题 计算题

根据图示情景和范例,编写计算题,并完成相关内容的填空。

【情景l】 要配制一定质量分数、一定质量的氯化钠溶液,应该怎么操作?

(1)编题范例 配制10%的NaCl溶液50g,需NaCl的质量和水的体积分别是多少?

(2)配制该溶液的操作步骤

①计算:

②称量:用托盘天平称取所需固体,再用______mL(选填“10”、“50”、“100”)的量筒量取所需的水;

③溶解:将称得的氯化钠固体放入烧杯中,再倒入量取的水,用玻璃棒充分搅拌;

④装瓶:将配好的溶液倒入试剂瓶,并贴上标签。

【情景2】 已知一定质量分数、一定质量的氢氧化钾溶液与一定质量的盐酸反应,得到只有一种溶质的溶液,求算反应后溶液的溶质质量分数。

(1)编写题目______________________________________________________________。

(2)计算过程

答案

【情景1】50(2分)

【情景2】(1)编写题目:已知56g10%的氢氧化钾溶液与18.5g某浓度的盐酸恰好完全反应,求所得溶液溶质的质量分数。 (1分)

(2)计算过程 (3分)

解:m(KOH)=56g×10%=5.6g

设反应生成的KCl的质量为x

KOH + HCl =" KCl" + H2O

56         74.5

5.6g         x

列比例式解得x=7.45g

ω(KCl)=  ×100%=10%

答:略。

要选择与所需量取液体体积最接近的容积的量筒,同时要比所量取的体积要大

可知氢氧化钠的质量,根据化学方程式列比例式进行解答

选择题
阅读理解

Early in the 18th century, Captain Cook, a famous explorer of Australia, unexpectedly caught sight of an unusual animal during his first visit to Australia. The animal had a large mouse like head and jumped along on its large legs. To his great surprise, the unusual animal carried its young in a special pocket of flesh. Captain Cook pointed to the animal which was eating grass in the distance and asked his native guide what the animal was referred to. The guide seemed not to know that he was pointing at and finally said “Kang-a-roo”, but their requests were met with puzzled looks of the native people. Before long they got to discover that the native guide who made the answer to Cook’s question really meant, “I don’t know what you pointing at. “ Funny enough, the name “ Kang-a-roo”, stuck and it is still in use today.

小题1:Which of the following sentences best expresses the main idea?

A.captain Cook’s guide made a joke.

B.Native Australians could not speak English in Cook’s time.

C.Some words have rather funny origins (起源).

D.Captain Cook was a lover of wild animals.小题2:When the native guide said “Kang-a-roo ”, he really meant “ ______”

A.Ah, it is a special kind of animal

B.I wonder what you have said

C.What do you mean by pointing at that animal?

D.I have no idea of what you are referring to.小题3:We can infer from this passage ______.

A.we should learn many different languages

B.Captain Cook made a mistake in understanding

C.Captain Cook was a foolish explorer

D.the importance of a language in common