问题 问答题

实验室现有下列仪器及高锰酸钾、大理石、稀盐酸、稀硫酸四种药品,小微同学想要制取某种气体.

请回答下列问题:

(1)写出仪器名称:②______,④______.

(2)根据所给仪器和药品判断可制取的气体是CO2(或二氧化碳),反应的化学方程式为______,制取该气体所选用的仪器为______(填序号).

(3)收集此气体应采用______,其原因是______.

答案

(1)仪器名称为集气瓶,铁架台.要求同学们要记住常用仪器的名字和使用方法.

(2)实验室制取二氧化碳用固体+液体→气体的反应制取二氧化碳,根据所给仪器和药品判断满足制取CO2的条件,

反应的化学方程式为CaCO3+2HCl═CaCl2+H2O+CO2↑,制取该气体所选用的仪器应该能组成发生装置和收集装置.

(3)因为二氧化碳的密度比空气的大,收集此气体应采用向上排空气法.

故答案为:(1)集气瓶.铁架台

(2)CO2(或二氧化碳)

CaCO3+2HCl═CaCl2+H2O+CO2↑,①②④⑤

(3)向上排空气;二氧化碳的密度比空气的大

单项选择题
单项选择题

Students should be allowed to study without worrying about grades. Fortunately, most educators are becoming aware of the fact that students have different interests and abilities. However, the discipline resulting from grades still exists. Grades often cut down creativity. Competing for better grades causes many students to turn down opportunities to pursue music, dramatics and sports. Grades impose a subjective standard of success on everyone. 1 do not demand as some extremists do, that grades be ended immediately. However, ! do believe that less emphasis should be placed on grades. I hope that someday grades will become optional at Village High School.
Magdalena Smith, President
Drama Club
Let’s face the facts about grades. Grades perform three basic functions. First, grades motivate students to work at their highest level of competence. Second, they act as a reward for hardworking students and as a scolding to students who do not work hard. Finally, grades are used as an effective standard by which to measure student achievement. Good grades help students to get jobs and to get in-to university, I’ve spoken with a number of students who have jobs, and most of them say that they were hired primarily on the basis of their grades. My grades helped me land a part-time job and will help me get into university next year. I think grades are extremely important at Village High School.
Simon Harper, Member,
Science Club

Which of the following states a fact about grades at Village High School

A.They are not useful.

B.They foster unnecessary competition.

C.They should be optional.

D.They are currently in us