(8分)某化学研究小组以铜为电极电解饱和食盐水,探究过程如下: 实验1:如图所示

题型:实验题

问题:

(8分)某化学研究小组以铜为电极电解饱和食盐水,探究过程如下:

实验1:如图所示连接装置,电源接通后,与电池负极相连的铜丝上有大量气泡产生;与电池正极相连的铜丝由粗变细.电解开始30 s内,阳极附近出现白色浑浊,然后开始出现橙黄色浑浊,此时测定溶液的pH约为10.随着沉淀量的逐渐增加,橙黄色沉淀慢慢聚集在试管底部,溶液始终未出现蓝色.

实验2:将实验1中试管底部的橙黄色沉淀取出,分装在两支小试管中,以后的操作和现象如下:

序号操作现象
滴入稀硝酸溶液沉淀溶解,有无色气泡产生,最终得到蓝色溶液
滴入稀硫酸溶液橙黄色沉淀转变为紫红色不溶物,溶液呈现蓝色
阅读资料:常见铜的化合物颜色如下:

物质颜色物质颜色
氯化铜固体呈棕色,浓溶液呈绿色,稀溶液呈蓝色氢氧化亚铜(不稳定)橙黄色
碱式氯化铜绿色氢氧化铜蓝色
氧化亚铜砖红色或橙黄色氯化亚铜白色
请回答下列问题:

(1)铜的常见正化合价为________、________,最终试管底部橙黄色沉淀的化学式________________.

(2)阴极上发生的反应为________________;阳极上发生的反应为________________.

(3)写出实验2中①、②的离子方程式:

①____________________________________,②______________________________.

考点:电解池原理电解池电极反应式的书写
题型:实验题

根据分割对象与背景之间的差异,产生了不同的确定阈值的方法。当前,主要应用的方法有()和()两种。

题型:实验题

The English are often considered as unfriendly people who don't talk to strangers, but not London taxi drivers. I once asked a cabbie to describe his life to me and he didn't stop talking until I arrived home half an hour later. He told me many interesting stories and this is one of them: “Some very strange things happen late at night. The other day I was taking a woman home from a party. She had a little dog with her. When we got to her house she found that she'd lost her key. So, I waited in the cab with the dog while she climbed up the window.”“ I waited … and waited … After half an hour of ringing the bell I decided to find out what was going on. I tied the dog to a tree and started to climb up the window. The next thing I knew was that the police came. They thought that I was trying to rob the house! Luckily, the woman came downstairs, she'd gone to sleep and forgotten about me and the dog. I was in such a hurry to get away that I forgot to ask her for the fare (车费).”

小题1:In the writer’s opinion, London taxi drivers are _____________.

A.unfriendly

B.talkative

C.helpful

D.strange enough小题2: From the passage we guess that the writer ______.

A.is the driver of the taxi

B.often travels by taxi

C.is a foreigner visiting London

D.lives in London小题3:What does the underlined word “cabbie” mean in this passage?

A.Conductor

B.Stranger

C.Taxi driver

D.author小题4:The man was waiting outside the woman's house because ______.

A.he began to like the woman and her dog at the first sight

B.the woman had not paid him

C.he wanted to know what would happen when the police came

D.he was trying to go on talking with her

题型:实验题

美国国家BIM标准(NBIMS2002)提出了BIM概念产生的背景。

题型:实验题

膨胀阀

题型:实验题

要保证飞机油气式减震支柱具有最佳减震性能,最关键的因素是:().

A.必须保证油和气的灌充量符合规定

B.必须保证油和气最适当比例灌充

C.必须保证预充气体的压力要尽量大

D.必须保证灌充油液的体积要尽量多

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