问题 问答题

乙炔(化学式C2H2)俗称电石气,实验室中常用电石(一种灰色块状固体,化学式CaC2)与水在常温下反应制取,该反应中同时还有氢氧化钙[Ca(OH)2]生成.通常情况下,乙炔是一种无色、无味、难溶于水的气体,标准状况下,乙炔的密度是1.16g/L(空气的密度为1.293g/L).乙炔在氧气中燃烧放出大量的热,火焰温度高达3000℃以上,可用来焊接或切割金属,在一定的条件下,乙炔还可以与氯化氢气体反应生成氯乙烯等.根据上述提供的信息,请你回答下列问题:

(1)指出下图中标号仪器的名称①______②______③______

(2)写出实验室制取乙炔的化学反应方程式______.

(3)上述信息中描述了有关乙炔的______种物理性质.

(4)在实验室中制取乙炔气体时,可采用上图中的发生装置为(填序号,下同)______,收集装置为______.

(5)实验室制取乙炔时,首先要进行的一步操作是______.

(6)乙炔在氧气中燃烧的化学方程式是______,根据你学到的知识,你认为在点燃乙炔气体前最需要注意的问题是______.

答案

(1)长颈漏斗、锥形瓶和集气瓶是实验室常用的仪器,故答案为:①长颈漏斗②锥形瓶③集气瓶

(2)碳化钙和水反应生成氢氧化钙和乙炔,配平即可,故答案为:CaC2+2H2O═Ca(OH)2+C2H2

(3)通常情况下,乙炔是一种无色、无味、难溶于水的气体,标准状况下,乙炔的密度是1.16g/L,描述了五种物理性质,故答案为:5

(4)实验室中常用电石与水在常温下反应制取,因此不需要加热;难溶于水,密度比空气略小,最好用排水法收集,故答案为:D、C

(5)制取气体时,首先要连接仪器,检验装置的气密性;故答案为:检验装置的气密性

(6)乙炔和氧气在点燃的条件下生成二氧化碳和水,因此乙炔具有可燃性,点燃之前要检验气体的纯度,不纯时容易引起爆炸.故答案为:2C2H2+5O2

点燃
.
4CO2+2H2O检验乙炔气体的纯度.

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                                                      JOB OPPORTUNITIES

     Law Office Manager/Administer

     Mature and energetic professional to handle administration, management and operations for the firm.

     Responsibilities: Responsible for daily operations of the firm. Including handling important and

confidential matters for the firm and clients. The position requires the ability to interact with all members of

the staff and a diverse group of clients. Organize President's emails and schedules as well as coordinate

staff meetings and events. Must have the ability to analyze and solve problems. Experienced in managing

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organizational skills, attention to details.

     Education Requirement: Bachelor's Degree. Bilingual English/Spanish a plus. Excellent benefits and

work environment. Salary is commensurate with experience.

Send resume(简历) with cover letter in confidence to:

     EMAIL: info@greencards.com

     ADDRESS:

     Alan Gordon Immigration and Naturalization Law 1018 East Boulevard - Suite 7 Charlotte, NC

28203

     FAX: 704 377 1172

     Experienced Immigration Paralegal(律师助手)

     Excellent work ethic, energetic and committed professional with background on family based and

business immigration law. Must have excellent communication skills both verbal and written and the ability

to interact with all members of the staff and different group of clients. Proven time management and

organization skills. Attention to details. Must be proficient in computer programs. Flexibility and positive

attitude are important. Bachelor's degree is required. Must pass credit and background checks. Salary is

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     Send resume with cover letter in confidence to:

     Email: info@greencards.com

     ADDRESS:

     Alan Gordon immigration and Naturalization Law 1018 East Boulevard - Suite 7 Charlotte, NC

28203

     FAX: 704 377 1172

1. If you want to apply for the law office manager you must ________.

A. have managed your own firm before

B. send emails to the President of the firm

C. have the ability to analyze social problems

D. have an excellent ability to work with other people

2. The underlined part "is commensurate with" most probably means "_______".

A. agrees with

B. devotes to

C. limits to

D. helps with

3. Both Law Office Manager and Experienced Immigration Paralegal ______.

A. offer good salaries

B. need good organization abilities

C. provide a good work environment

D. require understanding two languages

4. Tom wants to work as an experienced immigration paralegal, he _______.

A. had better be an immigrant

B. must have a doctor degree

C. must be good at computer programs

D. must be good at checking others' background

单项选择题