问题 填空题

(9分)漂白粉是日常生活中的一种常用消毒剂、杀菌剂和漂白剂。请根据要求回答问题:

(1)漂白粉的有效成分是次氯酸钙[Ca(ClO)2],将氯气通入熟石灰(含水的质量分数略小于1%)即可制取,该反应的化学方程式为 ______________________________。

(2)漂白粉具有漂白作用是因为Ca(ClO)2水解生成了次氯酸(HClO),写出该水解反应的离子方程式_______________________________

(3)Ca(ClO)2溶液中各离子浓度由大到小的顺序是____________________________

(4)空气中的二氧化碳可以可增强漂白粉的漂白效果,用化学方程式表示其原理__________________________________________

(5)漂白粉与洁厕剂等强酸性物质混合使用可生成一种有毒气体,写出该反应的离子方程式________________________________________

答案

(1)2Cl2+2Ca(OH)2 = CaCl2 +Ca(ClO)2 +2H2O (2分)

(2)ClO-+ H2O HClO +OH- (2分)  (3)c(ClO-)>c(Ca2+)>c(OH-)>c(H+)(1分)

(4)Ca(ClO)2+CO2 + H2O = CaCO3↓+2HClO (2分)(5)ClO- + Cl- + H+ = Cl2↑+ H2O (2分)

(1)考查漂白粉的制取,方程式为2Cl2+2Ca(OH)2 = CaCl2 +Ca(ClO)2 +2H2O 。

(2)次氯酸钙是强碱弱酸盐水解生成次氯酸,方程式为ClO-+ H2O HClO +OH-

(3)次氯酸钙由于水解显碱性,所以溶液中各离子浓度由大到小的顺序是c(ClO-)>c(Ca2+)>c(OH-)>c(H+)。

(4)碳酸的酸性强于次氯酸的,所以碳酸能制取次氯酸,方程式为Ca(ClO)2+CO2 + H2O = CaCO3↓+2HClO 。

(5)在酸性溶液中,ClO能氧化Cl生成氯气,方程式为ClO- + Cl- + H+ = Cl2↑+ H2O。

问答题
单项选择题

Throughout the 19th century and into the 20th, citizens of the United States maintained a bias against big cities. Most lived on farms and in small towns and believed cities to be centres of (1) , crime, poverty and moral (2) Their distrust was caused, (3) , by a national ideology that (4) farming the greatest occupation and rural living (5) to urban living. This attitude (6) even as the number of urban dwellers increased and cities became an essential (7) of the national landscape. Gradually, economic reality overcame ideology. Thousands (8) the precarious (不稳定的) life on the farm for more secure and better paying jobs in the city. But when these people (9) from the countryside, they carried their fears and suspicions with them. These new urbanities, already convinced that cities were (10) with great problems, eagerly (11) the progressive reforms that promised to bring order out of the (12) of the city.

One of many reforms came (13) the area of public utilities. Water and sewerage systems were usually operated by (14) governments, but the gas and electric networks were privately owned. Reformers feared that the privately owned utility companies would (15) exorbitant (过渡的) rates for these essential services and (16) them only to people who could afford them. Some city and state governments responded by (17) the utility companies, but a number of cities began to supply these services themselves. (18) of these reforms argued that public ownership and regulation would (19) widespread access to these utilities and guarantee a (20) price.

(5)()

A.superb

B.super

C.exceptional

D.superior