问题 实验题

某实验小组对实验室制取氢气的反应原理进行探究。

【知识回顾】能产生氢气的化学反应有: ①水电解     ②活泼金属与酸反应

【讨论交流】反应①的化学方程式                            ;同学们讨论后认为该反应不适用于实验室制取氢气。

【实验探究】为了探究哪种物质更适合用于实验室制取氢气,大家设计了如下实验:

【分析与结论】填写实验报告。

实验实验现象实验结论
A剧烈反应,迅速产生大量气泡,试管外壁       反应速率过快,气体不便收集,不能用于实验室制取氢气
B缓慢产生少量气泡反应速率过慢,不能用于实验室制取氢气
C 

较快产生大量气泡,试管外壁发热

                                 
通过实验得出,适合实验室制取氢气的化学反应方程式为                            ;

【知识拓展】(1)确定实验室制取气体的反应原理时,要考虑诸多因素,如反应的快慢、收集的难易、             等。

(2)用稀盐酸制取氢气时,制得的气体中可能会增加的杂质为          

答案

【讨论交流】2H2O2H2↑+ O2↑(2分) 【分析与结论】A的实验现象:发烫;C的实验结论:反应速率适中,适用于实验室制取氢气;Zn + H2SO4 ="=" ZnSO4 + H2↑【知识拓展】(1)反应条件(或成本、气体纯度等)(2分)(2)氯化氢(或HCl)

 

题目分析: 根据电解水的实验可以得到【讨论交流】反应①的化学方程式为2H2O2H2↑+ O2↑;【分析与结论】根据金属与酸反应的现象和金属活动性顺序可知,实验A中实验现象为剧烈反应,迅速产生大量气泡,试管外壁发烫;实验C的实验现象为较快产生大量气泡,试管外壁发热,可得出结论为反应速率适中,适用于实验室制取氢气;通过实验得出,适合实验室制取氢气的化学反应方程式为Zn + H2SO4 ="=" ZnSO4 + H2↑;【知识拓展】(1)确定实验室制取气体的反应原理时,要考虑诸多因素,如反应的快慢、收集的难易、反应条件(或成本、气体纯度等)等。(2)用稀盐酸制取氢气时,制得的气体中可能会增加的杂质为挥发出的氯化氢气体。

填空题

Your heart suddenly starts pounding so hard you think it’s going to leap right out of your chest. You’re sweating even though it’s cold out. You feel unsteady on your feet and generally shaky, like the world around you is spinning out of control and you can’t get a grip. Your hands and feet are numb and useless. You’re gasping for breath and feel like you’re drowning.

(41)__________Genetics may be part of the explanation; women are more prone to anxiety or depression, and a history of these mood disorders makes you more likely to have a panic attack. But unhappy life experiences may also increase women’s vulnerability.

A particularly active area of research at the moment is the effect of hormones. Women seem most susceptible to panic attacks during times of hormonal changes, such as adolescence, pregnancy, and so on. Dr. Lilian Gonsalves, psychology at the Cleveland Clinic, says some scientists think that hormonal fluctuation may upset the balance of chemicals in the brain that modulate fear and anxiety, triggering a panic attack. It feels like the fight-or-flight response gone wild with no provocation. (42)__________

Fear of another attack often makes people avoid places where an attack took place, and a small percentage of sufferers may eventually become housebound, a condition called agoraphobia. (43)__________ "We used to say that you don’t die of a panic attack, but I’ve stopped saying that," says Gonsalves. "It could be that during a panic attack you get coronary spasms or an irregular heart rate. "

(44)__________There’s no single cure that works for everyone, but generally, patients use medication, cognitive behavioral therapy or some combination of the two. Cognitive behavioral therapy teaches you a range of techniques—such as relaxation exercises—to deal with everyday anxiety and stress, lessening the chances of another attack. Many people find that drugs help control the problem until they can find a behavioral therapy that works, after which drugs may no longer be necessary. Research has also shown that regular exercise.and activities such as yoga may reduce the severity and number of attacks.

(45)__________If there is nothing wrong, then your doctor will probably refer you to a psychiatrist or psychologist who can work with you on the problem over what may be a period of several months.

It takes a while to feel completely better; generally, antidepressants start working in six to eight weeks, Gonsalves says. But many patients begin to get some relief in just two weeks, she adds. In all, about 80 percent of patients will do well. In the case of the other 20 percent, who don’t respond to treatment, doctors often find that they have missed an underlying medical condition that is behind the attacks.

[A] Suffering from frequent panic attacks also means you are at higher risk of depression, substance abuse and suicide. Some research also indicates that women who have repeated attacks are at higher risk of death.

[B] Call your doctor even if you’ve had only a single attack, because these symptoms could also signal a wide range of other problems, including thyroid and heart disease. A primary-care physician will first perform a physical exam and probably order an EKG and blood tests to rule out other possible causes of the attacks.

[C] You can be standing at a bus stop or shopping at the mall without any danger in sight, and suddenly, you feel like you’re dying. The attack is generally over in a few minutes, but sometimes symptoms—especially feeling faint and dizzy—can linger for mare than an hour.

[D] Many women report experiencing their first panic attack in late adolescence. But others have no trouble until they are around 50, when their hormone levels often vary wildly. "These are high functioning women who have never seen a psychiatrist before," says Gonsalves. "They start having hot flashes and they don’t sleep. They become acutely anxious. "

[E] If you have felt all of these come on without warning, you may have just suffered a panic attack. These frightening symptoms affect women twice as often as men, although scientists are not sure why.

[F] The cure of panic attacks often depends on the cause. If your attacks are triggered by a physical condition, they should be eliminated by treating the physical cause. If you can’t find the cause, continue looking and using the above tips to control the attacks.

[G] Because of the possible consequences of untreated panic attacks, it’s important to get help early. And fortunately, there is lot of help available.

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