问题 问答题 论述题

炸药爆炸后如果不能实现氧平衡有什么危害?

答案

参考答案:

炸药通常由碳、氢、氧、氮四种主要元素组成。其中碳和氢是可燃元素,氧是助燃元素,氮是惰性元素。炸药爆炸,主要是可燃元素碳、氢与助燃元素氧之间进行急剧氧化反应生成二氧化碳、一氧化碳和水蒸气的过程。而氧平衡则表达了化学反应过程中氧与可燃元素碳、氢之间所需原子数量之间的关系。炸药的氧平衡可分为下 * * 种情况;

1、零氧平衡。炸药中氧含量恰好与可燃元素完全氧化。这类炸药称为零氧平衡炸药。其特点是,炸药中的碳和氢都被氧化成二氧化碳和水蒸气,氧气得到充分利用。此时反应完全,放出热量最多,作功能量最大,而且不会生成有毒气体。

2、负氧平衡。炸药中的氧含量不足以将可燃元素充分氧化,这类炸药称为负氧平衡炸药。其特点是,负氧平衡时,因氧气不足,可燃元素未被充分氧化,生成一氧化碳和固体碳。一氧化碳为有毒气体,不仅对人体有害,而且在高温下与外界氧反应,能再次燃烧形成二次火焰。二次火焰和爆炸时生成的灼热固体碳粒,容易引起瓦斯、煤尘爆炸。

3、正氧平衡。炸药中氧含量足够将可燃元素充分氧化,并有剩余。这类炸药称为正氧平衡炸药。其特点是,正氧平衡时,炸药中的氧未被充分利用,剩余氧和游离氮化合,生成一氧化氮、二氧化氮等有毒

阅读理解

Boys need friends, suffer when they don't believe they have any, and worry over the ups and downs of relationships. Many adults believe that somehow boys need friends less than girls do, in truth, though, no boy is an island; boys value their friends throughout childhood and adolescence and are happier and healthier when they have solid relationships with peers(同龄人).

Despite the common belief that girls are better at relationships, most boys consider their friends a very important part of their lives, and boys may actually be better at keeping friendships than girls are. A recent study of 10 to 15­year­old boys and girls found that girls' friendships are actually more fragile. Girls tend to say and do hurtful things to each other more frequently than boys, and girls are more hurt by the end of a friendship.

Boys are the living definition of the phrase “peer group”; they love games with rules, competition, and doing things together. Boys seem to enjoy, even need the opportunity to test themselves against others, and many lasting friendships begin in karate(空手道) class or on the basketball court. Competence and skill are widely respected; being picked last for a team or left out altogether is an experience that can haunt(萦绕心头) a boy for years.

As boys mature(成熟), the friendship becomes even more important, and it frequently widens to include girls. During the teen years, friends can become the most important part of a boy's life—and a part in which his parents are not included. The confusion of being a teenager leads boys to form close bonds(关系) with friends. There is the sense for many boys that a friend is someone who is “always there for me”, someone he can trust. They may be partners in crime or partners in study, but the friendship of adolescent boys can run surprisingly deep.

小题1:The common belief of adults is that boys________.

A.don't care about others as much as girls

B.don't value friendship as much as girls

C.have the same friendship as girls

D.have healthier friendship than girls小题2:According to the text, boys' friendship________.

A.is usually built around active play

B.tends to be in small groups

C.can bear mutual hurt between friends

D.doesn't suffer from failure小题3:The author mentions the study in the second paragraph to prove ________.

A.many people believe girls are better at relationships

B.most boys consider their friends very important

C.boys may be better at keeping friendships than girls

D.boys may be more active in a friendship小题4:As a boy gets older, he tends to________.

A.widen his circle of friends to include different kinds of people

B.shift his focus from his friends to himself

C.leave his parents out of his friendship

D.be confused about what a friendship is小题5:What's the best title for the text?

A.Friendships between Boys and Girls

B.Boys and Their Friendship

C.Childhood and Adolescent Friendship

D.Tips on Making Friends with Boys

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