同学们在学习了盐的化学性质以后,开展了测定碳酸钠和氯化钠的固体混合物中碳酸钠的质

题型:问答题

问题:

同学们在学习了盐的化学性质以后,开展了测定碳酸钠和氯化钠的固体混合物中碳酸钠的质量分数的探究实验,他们设计了以下实验方案

【方案一】气体转化法

(1)如图1所示,把wg的混合物与足量稀硫酸反应后,测定产生的CO2的体积,检查该装置气密性的方法是______;

(2)有同学提出用图2代替图1中的收集装置,则所测得CO2气体的体积______;

(填偏大、偏小或不变)理由是______,你的改进方案是______;广口瓶内原有的空气对实验结果______(填“有”或“没有”)影响,如果利用改进后的装置测得CO2气体的体积为Vml (此时CO2的密度为Pg/ml)则原混合物中Na2CO3的质量分数的计算式为______;

(3)也有人用图3装置测定CO2的质量(碱石灰的成分是CaO和NaOH的混合物)则图3实验装置中主要存在哪些缺陷?这些缺陷对实验结果有何影响?

主 要 缺 陷对实验结果的影响
  
  
【方案二】沉淀法(如图所示)

(1)沉淀A的化学式是______,溶液M中溶质的化学式是______;

(2)确定CaCl2溶液是否过量的方法是______;

(3)该固体混合物中Na2CO3的质量分数的计算式为______;

(4)导致测定结果偏大的原因可能是______;

【方案三】盐酸滴定法

(1)“操作2”的名称是______;

(2)根据实验数据计算该固体混合物中Na2CO3的质量分数为______(保留一位小数).

考点:盐的性质常见仪器和装置的用途化学实验方案设计和实验现象的分析化学反应方程式的计算
题型:问答题

下列各组词语中,加点的字有两种读音的一组是(    )

A.解元解数解劝解甲归田

B.和声和面和诗曲高和寡

C.咀嚼倒嚼嚼舌咬文嚼字

D.打场场院市场逢场作戏

题型:问答题

It is a good time ______. [ ]

A. go hiking

B. to go hiking

C. going hiking

D. went hiking

题型:问答题

血液循环的运输器官是[ ]

A.心脏

B.动脉

C.静脉

D.毛细血管

题型:问答题

Along a long path we came to a deep valley, on the far side of which the path led into some very thick bushes. Rather than push through up again and rejoin the path on the far side of the bushes.

As I climbed down into the valley a bird flew off h rock on which I had put my hand. On looking at the spot from which the bird had risen, I saw two eggs. They were the kind that I did not have in my collection, so I placed them carefully in my bag, wrapped in a little dry grass.

As we went further down the valley the sides became steeper and not far from where I had entered. It came to drop of about twelve to fourteen feet. The water that rushed down all these small valleys in the rainy season had worn the rock as glass. As it was too deep to climb down, I handed my gun to one of the men and slid down it. My feet had hardly touched the sandy bottom when the two men jumped down, one on each side of me. They quickly gave me the gun and asked me if I had heard the tiger. In fact, I had heard nothing; possibly because of the noise I made sliding down the rock. The men said they had heard a tiger growling somewhere nearby, but they did not know from which direction the noise had come.

小题1:According to the text we know that __________.

A.the writer decided to push through the thick bushes

B.the writer decided to walk along the valley

C.the writer wanted to stop climbing

D.the writer tried to find two eggs小题2:When the writer found the eggs, he ________.

A.wrapped them in dry grass and put them aside

B.wrapped them in dry grass and took them with him

C.tried to find the bird

D.made the bird fly off小题3:At the end of the story, the writer knew that ____________.

A.a tiger had run away

B.a tiger was close to them

C.the men had seen a tiger

D.a tiger had seen them小题4:Which of the following orders is RIGHT about what happened in their travel?

A.hear the sound of tiger→find eggs→push through the bushes→climb down into the valley

B.climb down into the valley→push through the bushes→hear the sound of tiger→find eggs

C.push through the bushes→climb down into the valley→find eggs→hear the sound of tiger

D.find eggs→climb down into the valley→hear the sound of tiger→push through the bushes

题型:问答题

(53—54题共用题干)王女士在回家路上看见一人躺在路上,询问得知,此人骨折。

骨折的急救下列错误的是

A.镇痛、止血、包扎伤口

B.有休克的立即送医院

C.妥善固定伤肢

D.要严密观察病情变化

E.搬运、护送要平稳

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