问题 填空题

水的电离平衡曲线如图所示:

(1)若以A点表示25℃时水的电离平衡时离子的浓度,当温度升高到100℃时,水的电离平衡状态到B点,则此时水的离子积从______增加到______.

(2)已知25℃时,0.1L0.1mo/L的NaA溶液的pH=10,则HA在水溶液中的电离方程式为______.

(3)100℃,将pH=9的NaOH溶液与pH=4的硫酸溶液混合,若所得混合溶液pH=7,则NaOH溶液与硫酸溶液的体积比为______.

(4)100℃时,若10体积的某强酸溶液与1体积的某强碱溶液混合后溶液呈中性,则混合之前,该强酸的pH与强碱的pH之间应满足pH+pH=______.

答案

(1)水的离子积KW=c(H+)•c(OH-),25℃时,KW=c(H+)•c(OH-)=10-7×10-7=10-14;100℃时,KW=c(H+)•c(OH-)=10-6×10-6=10-12

故答案为:10-14;10-12

(2)由于0.1L 0.1mo/L的NaA溶液的pH=10,说明溶液显示碱性,HA属于弱电解质,电离方程式为:HA⇌H++A-

故答案为:HA⇌H++A-

(3)设氢氧化钠溶液的体积为xL,硫酸溶液的体积为yL,pH=9的NaOH溶液中,氢氧根离子的浓度为:10-3mol/L,pH=4的硫酸溶液中氢离子浓度为:10-4mol/L,

二者混合后溶液的pH=7,溶液酸性碱性,溶液中氢氧根离子的浓度为10-5mol/L,即氢氧化钠过量,即10-3mol/L×xL=10-4mol/L×y+10-5mol/L(x+y),

解得x:y=1:9,

故答案为:1:9;

(4)设强酸溶液的pH为a,体积为10V,溶液中氢离子浓度为:10-amol/L;碱溶液的pH为b,体积为V,溶液中氢氧根离子的浓度为:10-(12-b)mol/L,

混合后溶液呈中性,则满足溶液中氢离子的物质的量大于氢氧根离子的物质的量,即10-amol/L×10VL=10-(12-b)mol/L×VL,

解得:1-a=b-12,a+b=13,

故答案为:13.

问答题

Passage 1 It is a great honor for me to speak at one of China’s great academic institutions -- one that is helping to revive and maintain your country’s historic tradition of leading the world in science and technology, and one whose alumni are to be found in positions of leadership throughout the country. Here, as in so many other places in China, no visitor can help feeling the excitement of a great country developing at breakneck speed, and every day opening up new vistas of knowledge and opportunity to its citizens. You can be really proud of your country and what it has achieved in the last 25 years.// As I look out over the young faces in this audience I cannot help envying the international students -- more than a thousand, I am told, from over 50 countries -- who have the privilege of sharing your learning experience here. It reminds me for a moment of my own student days, when my country, Ghana, was newly independent. We felt we were suddenly reaching out to the world, and making new discoveries every day. But then I also remember that times of rapid change can bring pain and confusion, even destruction, as well as progress and excitement.// The more rapid and exciting it is, the more change calls for careful management, and wise, humane leadership. Order and stability have to be preserved, but without choking off the freedom to enquire, and experiment, and express oneself, since -- as you young researchers know better than anyone -- knowledge and science have a vital role in national development. And technical expertise needs to be harnessed to the development and security of society as a whole, so that it not only creates greater wealth for the few, but enables all citizens to feel safer and more prosperous.// The development of such a great country as China cannot happen in isolation. It affects the whole world, and it draws you into new relationships with other parts of the world. Increasingly, your economy depends on exchanges with other countries -- both imports and exports, of both goods and capital. Foreign investment plays an essential role in your growth, while your holdings of foreign currencies -- and your management of your own currency -- are coming to play a vital part in the international monetary system. This means that you have a stake in the development and prosperity of the wider world. And your security, too, depends on international peace and stability.// Your Government shows that it understands this, by the role that it plays in the United Nations, and elsewhere. And, increasingly, Chinese citizens are called on to take risks, and make sacrifices, in the interests of global security. It was impressive to see, in our newspapers the other day, pictures of Chinese policemen in blue helmets preparing to join the United Nations mission in Haiti -- an island buffeted by both human and meteorological storms, which is literally on the far side of the world from here. So I am here, in part, to express the world’s gratitude. Clearly, you in China have understood, as your saying goes, that we all "share the same breath". Human misery knows no frontiers, and nor should human solidarity.//

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