问题 问答题

下图是实验室制取气体的一些装置,据图回答问题.(以下所选装置均填装置序号)

(1)写出指定仪器的名称①______;②______.

(2)向气体发生装置内加入药品前,应该进行的操作是______;

(3)如果用过氧化氢溶液同二氧化锰混合制氧气,要得到平稳的氧气流,应选用的气体发生装置是______;

(4)用加热氯酸钾和二氧化锰的混合物制取氧气,应选用的装置组合为______或______,反应的文字表达式为______;

(5)B装置中试管口略向下倾斜的原因是______,如果用该装置来加热高锰酸钾制氧气,需要改进的地方是______;

(6)能用E装置收集的气体,必须具备的性质是______;

(7)若装置C中反应剧烈,从实验安全角度考虑,可采取的措施有______(填序号).

①用容积较小的锥形瓶       ②控制液体的滴加速度

③加热反应物               ④降低反应物浓度.

答案

(1)直接写出仪器名称为试管、集气瓶;

(2)在制取气体前必须检查装置的气密性;

(3)要得到平稳的氧气流可以通过控制滴加过氧化氢的量的方法来达到目的,所以可以用A装置;

(4)加热氯酸钾和二氧化锰来制取氧气应该用B作为发生装置,根据氧气的密度比空气的大,难溶于水,可以选用D或F来收集;

(5)在固体物质会吸收一些水分,所以在加热时会变成水蒸气,在遇冷会变成液态的水,所以为了防止冷凝水炸裂试管,需将试管口略向下倾斜;

(6)E装置为向下排空气法收集气体,要求密度比空气小,且不与空气中的成分反应;

(7)反应物的接触面积和浓度都会影响反应速率.

故答案为:(1)①试管;②集气瓶;

(2)检查装置气密性;

(3)A;

(4)BD或BF;氯酸钾

催化剂
.
氯化钾+氧气;

(5)防止试管口的冷凝水回流使试管破裂;试管口放一团棉花;

(6)密度比空气小且不与空气中的物质反应;

(7)②④.

单项选择题 A3/A4型题
单项选择题

Feeling anxious Your mood may actually change how your dinner tastes, making the bitter and salty flavors recede, according to new research. This link between the chemical balance in your brain and your sense of taste could one day help doctors to treat depression. There are currently no on-the-spot tests for deciding which medication will work best in individual patients with this condition. Researchers hope that a test based on flavor detection could help doctors to get more prescriptions right first time.

It has long been known that people who are depressed have lower-than-usual levels of the brain chemicals serotonin or noradrenaline, or in some cases both. Many also have a blunted sense of taste, which is presumably caused by changes in brain chemistry. To unpick the relationship between the two, Lucy Donaldson and her colleagues at the University of Bristol, UK, gave 20 healthy volunteers two antidepressant drugs, and checked their sensitivity to different tastes. The drug that raised serotonin levels made people more sensitive to sweet and bitter tastes, the team reports in the Journal of Neuroscience. The other, which increased noradrenaline, enhanced recognition of bitter and sour tastes.

In healthy people, volunteers whose anxiety levels were naturally higher were less sensitive to bitter and salty tastes. "What hasn’t been done beore is to look precisely at which tastes are affected in depression," says Donaldson. Now the results are in, "we can discriminate between the chemicals and the tastes that seem to be altered," she says. Testing sensitivity to sweet and sour tastes could potentially help doctors to pick up on which chemicals are dipping, guiding them when choosing which drug to rectify the problem.

Currently, doctors rely on physical and emotional symptoms to make a best guess at an individual’s imbalance, prescribe a drug and wait about a month to check on any improvement. Good doctors have about a 60-80% success rate in selecting the right drug the first time, says psychiatrist Jan Melichar, a co-author on the paper. Are there any decent tests for prescribing drugs for depression "No. We do a best guesstimate," says Melichar. "I’m excited by this finding because in 3, 5 or 7 years we could have a simple taste test. "

Next, the team plans to perform similar tests in depressed people, and in healthy volunteers given another brain chemical called tryptophan. This chemical would lower the healthy subjects’ levels of serotonin, as actually happens in depressed patients.

The work has also generated interest from flavor houses--companies that develop chemicals for the food and drink industry--who are interested in making foods taste just as sweet with half the amount of sugar. "Theoretically there would be the possibility of enhancing your meal with drugs that affect brain chemicals so that things would taste better--you couid have a ’designer taste tablet’," Donaldson says.

Which of the following would be the best title for the text()

A. Mood Makes Food Taste Different

B. Depressed People’s Moods

C. The Best Prescription for Depression

D. Mood and Food Taste