实验室常用氯酸钾晶体和二氧化锰粉末制取氧气（装置A），也可用_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题问答题

实验室常用氯酸钾晶体和二氧化锰粉末制取氧气（装置A），也可用过氧化氢溶液和催化剂二氧化锰粉末来制取氧气（装置B）．装置B中的仪器a是分液漏斗，通过活塞的“开”、“关”可以随时滴加过氧化氢溶液，从而控制得到氧气的量．

（1）写出一种实验室制取氧气的化学方程式：______．

（2）从反应物状态和反应条件来比较装置A和B的差异：

	装置A	装置B
反应物状态	______	______
反应条件	______	______

（3）用装置B制得的氧气带有少量水蒸气，可用浓硫酸除去水蒸气，请在下列方框中添上带橡皮塞的玻璃导管，完成除去水蒸气的实验装置图．

（4）用向上排空气法收集氧气，并用带火星的木条放在集气瓶口检验氧气是否收集满．这是利用了氧气的______、______性质．

答案

（1）实验室加热氯酸钾和二氧化锰的混合物制取氧气的化学反应式是：2KClO₃

MnO2

.

△

2KCl+3O₂↑；

故答案为：2KClO₃

MnO2

.

△

2KCl+3O₂↑；

（2）装置A，反应物的状态是固体，反应条件是加热；装置B，反应物的状态是液体，反应的条件是不需加热．具体见下表：

反应物为固体	反应物为液体
需要加热	不需要加热

（3）注意导管要长进短出，并画出瓶塞．如图：

（4）氧气密度大于空气的密度，可用向上排空气法收集；因氧气有助燃的性质，可用带火星的木条放在集气瓶口检验氧气是否收集满．

故答案为：氧气密度比空气大；助燃性（可支持燃烧）．

多项选择题

张三、李四、王五都是河西村的村民。三家毗邻而居，依次是张家、李家、王家。请根据这些情况和下列各问中设定的条件回答问题。

王家院子中有一棵大树，枝繁叶茂。一日，暴风雨来袭，大树被风刮倒，恰好倒在路边。张三、李四发现后要求王五尽快把树移开，王五迟迟未动。后张三岳母陈某来张家看望外孙时，不慎被树木绊倒，花去医药费若干。请问，下列说法正确的是：( )。

A．树木是被风刮倒的，王某对陈某的受伤没有责任

B．陈某应自行负担医药费

C．王某明知自家的树倒在路上妨碍了别人行走，却迟迟不移，王某对陈某的受伤有过错，应承担侵权责任

D．王某应对陈某承担损害赔偿责任

单项选择题

Mayor: Four years ago when we reorganized the city police department in order to save money, critics claimed that the reorganization would make the police less responsive to citizens and would thus lead to more crime. The police have compiled theft statistics from the years following the reorganization that show that the critics were wrong. There was an overall decrease in reports of thefts of all kinds, including small thefts.
Which of the following, if true, most seriously challenges the mayor’s argument

A．When city police are perceived as unresponsive, victims of theft are less likely to report thefts to the police.

B．The mayor’s critics generally agree that police statistics concerning crime reports provide the most reliable available data on crime rates.

C．In other cities where police departments have been similarly reorganized, the numbers of reported thefts have generally risen following reorganization.

D．The mayor’s reorganization of the police department failed to save as much money as it was intended to save.

E．(E) During the four years immediately preceding the reorganization, reports of all types of theft had been rising steadily in comparison to reports of other crimes.