题干

在学完氧气的性质后,某校课外小组同学对铁丝在氧气中燃烧的实验进行了更深入的探究.

说明:下述实验中所用的8根铁丝均从1根长铁丝上截取,并且长度相同.

探究1:铁丝燃烧是否需要纯氧?

实验内容:取5根铁丝,分别在体积分数为90%、70%、65%、60%、55%的氧气中进行实验.

实验记录如下:

V(O2)%

实验现象

90%

燃烧剧烈,燃烧时间长,实验成功

70%

燃烧比90%的弱,燃烧时间短,实验成功

65%

燃烧比70%的弱,燃烧时间比70%的短,实验成功

60%

燃烧比65%的弱,燃烧时间更短,实验成功

55%

难以燃烧,只是发红

探究2:铁丝绕成螺旋状的原因是什么?

关于铁丝绕成螺旋状的原因,甲同学认为是为了增大与氧气的接触面积,乙同学认为是聚热效果好,能使未燃的铁丝更好的预热.在老师的指导下,小组同学进行了实验,实验操作及现象如下表所示,实验中3个集气瓶均盛有等量的水和体积分数相同的氧气.

实验操作

实验现象

取3根铁丝,将1根拉直,另两根绕成宽窄不同的螺旋状,进行如图所示实验.

铁丝均燃烧,剧烈程度不同,II最剧烈,其次是 III,较弱的是 I.

回答下述问题:

(1)铁丝在氧气中燃烧的化学反应方程式为____ .

(2)通过探究1实验,丙同学得出结论:铁丝在氧气中燃烧,所需氧气的最低体积分数为60%,你对他得出的结论的看法是____ .

(3)探究2实验中,3根铁丝均要完全伸入集气瓶中的原因是____ 

(4)根据探究2实验,你认为____ (填“甲”或“乙”)同学说法合理,其理由是____ .

(5)探究1实验用排水法收集氧气时,每瓶都要留存30mL水,以防止熔融物炸裂瓶底.实验中收集体积分数为90%的氧气时,设应向空集气瓶中加入水的体积为x,请列出能求解x的计算式____ (空集气瓶容积为310mL,不考虑橡皮塞所占体积).

上一题 下一题 0.0难度 选择题 更新时间:2015-03-25 09:08:33

答案(点此获取答案解析)

3Fe+2O2Fe3O4,\u7ed3\u8bba\u9519\u8bef\uff0c\u5e94\u8be5\u572860%\u300155%\u518d\u9009\u62e9\u4e00\u4e9b\u6570\u636e\u8fdb\u884c\u9a8c\u8bc1,\u589e\u5927\u53cd\u5e94\u7269\u4e0e\u6c27\u6c14\u7684\u63a5\u89e6\u9762\

同类题5

阅读理解

Cocoa Beach /Jupiter Surf Camp — Summer

Summer Surf Camp is centrally located on the Best Western seashore in Cocoa Beach & Jupiter at Carlin Beach Park with accommodations(住宿) at the Holiday Inn Express in Juno Beach.

Summer Surf Camp Dates:

● Surf Camp — Session 1     May 27th—30th         Family Surf Week (All Ages)

● Surf Camp — Session 2     June 2nd—6th           Family Surf Week (All Ages)

● Surf Camp — Session 3     June9th—13th           Team Week (Ages 12—17)

● Surf Camp — Session 4     June16th—20th          Family Surf Week (All Ages)

● Surf Camp — Session 5     June23rd—27th          Adults Only (18 and over)

● Surf Camp — Session 6     June30th—July 3rd       Family Surf Week (All Ages)

● Surf Camp — Session 7     July 7th—11th           Family Surf Week (All Ages)

● Surf Camp — Session 8     July 14th—18th          Women's Camp (18 and over)

● Surf Camp — Session 9     July 21st—25th          Family Surf Week (All Ages)

● Surf Camp — Session 10    July 28th—August 1st     Adults Only (18 and over)

* A 20% discount will be applied to the 4-Day Surf Camp Weeks.

* Parents are always welcome to sign up and join their children during the teen week surf camp sessions.

Summer Camp Details:

● Use coupon(优惠券) code: “Camp5” at checkout to get the 5% discount

* Daily Rate: $125.00 / person

* Surf Camp Runs: 9:30 am — 2:30 pm

● Please note: We don't supervise(监督) the campers after 2: 45 pm.

* Directions to Camp: click here

Contact us: 888-672-4887 info@floridasurflessons.com