为您找到与光电效应方程电路图如何理解相关的共200个结果:
光电效应是物理学中一个重要而神奇的现象。在高于某特定频率的电磁波照射下,某些物质内部的电子会被光子激发出来而形成电流,即光生电。光电现象由德国物理学家赫兹于1887年发现,而正确的解释为爱因斯坦所提出。科学家们在研究光电效应的过程中,物理学者对光子的量子性质有了更加深入的了解,这对波粒二象性概念的提出有重大影响。
发生光电效应时,电子克服金属原子核的引力逸出时,具有的动能大小不同。金属表面上的电子吸收光子后逸出时动能的最大值,称为最大初动能。
浏览量:3
下载量:0
时间:
光电效应中,金属中的电子在飞出金属表面时要克服原子核对它的吸引而做功。某种金属中的不同电子,脱离这种金属所需的功不一样,使电子脱离某种金属所做的功的最小值,叫做这种金属的逸出功。
电子吸收光子的能量后,可能向各个方向运动,有的向金属内部运动,有的向外运动,由于路程不同,电子逃逸出来时损失的能量不同,因而它们离开金属表面时的初动能不同。只有直接从金属表面飞出来的电子的初动能最大,这时光电子克服原子核的引力所做的功叫这种金属的逸出功。
浏览量:2
下载量:0
时间:
一元二次方程计算题100道(含答案)
一元二次方程是一个二次方程,它的一般形式为ax?+bx+c=0,其中a、b、c是系数,且a≠0。通过解这个方程,我们可以找到一个未知数的值。以下是小编为大家收集的关于一元二次方程计算题100道的相关内容,供大家参考!
一元二次方程的解法有很多种,包括公式法、配方法、因式分解法等。
其中,公式法是最常用的方法之一,它可以直接通过公式求解一元二次方程的根。
公式法:
对于一元二次方程ax?+bx+c=0,其解的公式为:
x=[-b±√(b?-4ac)]/2a
例如,对于方程2x?-4x+1=0,我们可以使用公式法来求解:
方程为:2x?+-4x+1=0
解的公式为:x=[4±√(-4?-4×2×1)]/2×2
方程的解为:x1=1.7071067811865475, x2=0.2928932188134524
另外,还有配方法、因式分解法等解法,但公式法是最常用的方法之一。
浏览量:4
下载量:0
时间:
一元一次方程知识点大全
一元一次方程是一种最简单的方程,它只含有一个未知数,并且未知数的最高次数是。以下是小编为大家收集的关于一元一次方程知识点的相关内容,供大家参考!
1. 0.5x-0.7=6.5-1.3x 2、1-2(2x+3)= -3(2x+1)
3、2(x-2)-3(4x-1)=9(1-x) 4、 2(x+1)-24=3(x-2)
2、7(2x-1)-3(4x-1)=4(3x+2)-1; 6、(5y+1)+ (1-y)= (9y+1)+ (1-3y
3、[ ( 20×)-4 ]=x+2; 8、20%+(1-20%)(320-x)=320×40%
4、2(x-2)+2=x+1 10、2(x-2)-3(4x-1)=9(1-x)
5、11x+64-2x=100-9x 12、15-(8-5x)=7x+(4-3x)
6、1 2x-10.3x=15
7、2 0.52x-(1-0.52)x=80
8、5 3x+5(138-x)=540 20、6 3x-7(x-1)=3-2(x+3)
浏览量:2
下载量:0
时间:
一元一次方程常见练习题及答案(可下载)
一元一次方程是一种最简单的方程,它只含有一个未知数,并且未知数的最高次数是。以下是小编为大家收集的关于一元一次方程练习题的相关内容,供大家参考!
一、填空题
1、-2,2;2、2、- ,x=5y=1,x=8y=2;3、-1;
4、 ,12;5、0;6、2;7、-1,-1;8、3,3;
9、10;10、x=1y=16,x=2y=12,x=3y=8,x=4y=4;
11、4;12、x= y= ;13、1;14、x=0y=1;15、12;
16、-43;17、42,15;18、6,3。
二、选择题
1、C;2、C;3、B;4、D;5、C;6、D;7、B;
8、A。
三、解答题
1、a=1,b=-3,c=-7;当x=3时,y=3。
2、(1)x= y= ;(2)x=-1y=2z=-3
3、设一只小猫x元,一只小狗y元,则x+2y=702x+y=50,解得x=10y=30,答一只小猫10元,一只小狗30元。
4、解(1)设该队胜x场,平y场,则x+y+3=123x+y=19,解得x=5y=4,答该队胜5场,平4场。
(2)5×1500+4×700+12×500=16300(元)
答该队每名队员在12轮比赛结束后总收入为16300元。
5、解:(1)七步梯、九步梯的扶杆长分别是5米、6米;横档总长分别是3.5米、5.4米(各1分);联结点个数分别是14个、18个。
(2)设扶杆单价为x元/米,横档单价为y元/米。依题意得4x+2y+1×10=265x+3.5y+1×14=36即2x+y=85x+3.5y=22,解得x=3y=2,故九步梯的成本为6×3+5.4×2+1×18=46.8(元)。
浏览量:4
下载量:0
时间:
一元一次方程练习题(带答案)
一元一次方程是一种最简单的方程,它只含有一个未知数,并且未知数的最高次数是。以下是小编为大家收集的关于一元一次方程练习题的相关内容,供大家参考!
一元一次方程的标准形式是ax+b=0(a,b是常数,a≠0),解这个方程可以得到一个未知数的值。
首先,我们需要将方程化为标准形式。如果方程中没有未知数,则可以直接得到答案。
然后,我们可以根据以下步骤求解:
将方程化为ax=b的形式。
如果a=0,则方程无解。
如果a≠0,则方程有唯一解x=b/a。
例如,对于方程2x+3=7,我们可以将其化为标准形式2x=4,然后得到唯一解x=2。
现在我们来求解一个具体的一元一次方程:
设方程为3x+5=8,我们首先将其化为标准形式:
得方程:3x+5=8
然后,我们使用solve函数求解:
解得:x=1
浏览量:4
下载量:0
时间:
阿房宫赋阅读理解题及答案免费下载
杜牧的《阿房宫赋》作于唐敬宗宝历元年,本文借写阿房宫的兴建与毁灭,揭露了秦朝统治者的穷奢享乐,那么关于这篇文章我们怎么学习呢?以下是小编准备的一些阿房宫赋阅读理解题及答案,仅供参考。
六国的君主灭亡了,全国(为秦所)统一;蜀地的山(树木被砍尽,)光秃秃的,阿房宫建造出来了。它(面积广大,)覆压着三百多里地面,(宫殿高耸,)把天日都隔离了。它从骊山向北建筑,再往西转弯,一直走向咸阳。渭水、樊川浩浩荡荡的,流进宫墙里边。五步一座楼,十步一个阁,走廊如绸带般萦回,牙齿般排列的飞檐像鸟嘴向高处啄着。楼阁各依地势的高低倾斜而建筑,(低处的屋角)钩住(高处的)屋心,(并排相向的)屋角彼此相斗。盘结交错,曲折回旋,(远观鸟瞰,)建筑群如密集的蜂房,如旋转的水涡,高高地耸立着,不知道它有几千万座。没有起云,为什么有龙?原来是一座长桥躺在水波上。不是雨过天晴,为什么出虹?原来是天桥在空中行走。(房屋)忽高忽低,幽深迷离,使人不能分辨东西。歌台上由于歌声响亮而充满暖意,有如春光融和;舞殿上由于舞袖飘拂而充满寒意,有如风雨凄凉。一天里边,一座宫殿中间,气候却不一样。
六国的宫妃和王子王孙。辞别六国的宫楼,走下六国的宫殿,坐着辇车来到秦国。他们早上歌唱,晚上奏乐,成为秦国的宫人。明亮的星星晶莹闪烁,这是宫妃们打开了梳妆的镜子;乌青的云朵纷纷扰扰,这是宫妃们在梳理晨妆的发髻;渭水涨起一层油腻,这是宫妃们抛弃了的胭脂水;烟霭斜斜上升,云雾横绕空际,这是宫中在焚烧椒、兰制的香料;雷霆突然震响,这是宫车驶过去了;辘辘的车声越听越远,无影无踪,不知道它去到什么地方。每一片肌肤,每一种容颜,都美丽娇媚得无以复加。宫妃们久久地站着,远远地探视,盼望着皇帝来临。有的宫女竟整整三十六年没能见到皇帝。
燕赵收藏的金玉,韩魏营谋的珍宝,齐楚的精华物资,在多少世代多少年中,从他们的人民那里掠夺来,堆叠得像山一样。一下子不能保有了,都运送到阿房宫里边来。宝鼎被当作铁锅,美玉被当作顽石,黄金被当作土块,珍珠被当作沙砾,丢弃得到处接连不断,秦人看起来,也并不觉得可惜。
唉,一个人的意愿,也就是千万人的意愿啊。秦皇喜欢繁华奢侈,人民也顾念他们自己的家。为什么掠取珍宝时连一锱一铢都搜刮干净,耗费起珍宝来竟像对待泥沙一样。(秦皇如此奢侈浪费,)致使承担栋梁的柱子,比田地里的农夫还多;架在梁上的椽子,比织机上的女工还多;梁柱上的钉头光彩耀目,比粮仓里的粟粒还多;瓦楞长短不一,比全身的丝缕还多;或直或横的栏杆,比九州的城郭还多;管弦的声音嘈杂,比市民的言语还多。使天下的人民,口里不敢说,心里却敢愤怒。(可是)失尽人心的秦始皇的思想,一天天更加骄傲顽固。(结果)戍边的陈涉、吴广一声呼喊,函谷关被攻下,楚项羽放一把火,可惜(华丽的阿房宫)化为了一片焦土。
唉!灭亡六国的是六国自己,不是秦国啊。族灭秦王朝的是秦王朝自己,不是天下的人啊。可叹呀!假使六国各自爱护它的人民,就完全可以依靠人民来抵抗秦国。假使秦王朝又爱护六国的人民,那就顺次传到三世还可以传到万世做皇帝,谁能够族灭它呢?(秦王朝灭亡得太迅速)秦人还没工夫哀悼自己,可是后人哀悼他;如果后人哀悼他却不把他作为镜子来吸取教训,也只会使更后的人又来哀悼这后人啊。
浏览量:3
下载量:0
时间:
兰花,美丽绚丽,象征顽强蓬勃的生命力,那么孔林二月兰有象征什么呢?通过阅读《孔林二月兰》,你应该会有所感悟。下面是读文网小编网络整理的《孔林二月兰》阅读题目及答案,相信会对你有所帮助!
19.内容上,用燕园和冷杉园里的二月兰衬托“我”对孔林二月兰的深爱不止,情有独钟。结构上,总领下文,引出下文对孔林二月兰的描写。
20.⑴面积广,数量多⑵自由开放,不求闻达⑶色彩艳丽、具有梦幻色彩⑷香气清雅圣洁⑸花朵美丽可爱⑹次第开放,精神抖擞
21.⑴运用了拟人、比喻 的修辞手法。,形象生动地描写了二月兰初绽时的情态,表达了作者对二月兰的喜爱之情。⑵紧尽着性子“毫不退让”“不顾一切”这几个词,运用拟人的手法生动形象地写出了二月兰开放时不怯不退的气度,绽放的倔强与自由,表达了作者对二月兰蓬 勃生命力的赞美之情。
22.孔林的二月兰,愈抑愈扬,美丽绚丽,具有顽强蓬勃的生命力;不求闻达,不谋地位,具有淡泊名利的高尚品质;坚忍柔韧,自由倔强,彰显生命向上的力量;既能与乡亲百姓亲密无间,又能感动润泽八方学人的心灵。
猜你还感兴趣的:
浏览量:3
下载量:0
时间:
父爱,都是细腻而深沉,面对父爱,你有什么理解和感悟?也许《老头子的固定电话》这片文章能为你找到答案。以下是由读文网小编收集整理的《老头子的固定电话》阅读题目及答案,欢迎您的阅读!
16.jié 覆 藉
17.事件③:父亲用我买的答录电话为我录音。事件④:我和先生争吵后,父亲在电话中感到我受了委屈。事件⑤:父亲去世后,我不同意拆除固定电话。事件⑥:除夕夜,父亲的电话录音暖和了我的心。
18.⑴矫情:年老的父亲看到录像中我跪拜给公婆奉茶,心疼得跺脚、落泪;这些表现与他的年龄不符,显得有些夸张。(2分)⑵感动:我出嫁那天父亲一直没有等到我的电话,以为我受了委屈,一夜未眠;他对我的牵挂和疼爱让我心生感动。(2分)
19.示例1:“慢慢”形象地写出了父亲此时说话的情形,与“一向快言快语”形成对比(2分);表现出父亲说话时父亲的情感,体现了父亲对“我”的担心、牵挂和疼爱等情感(2分)。
示例2:画线句是对父亲的语言描写,形象地写出父亲欲方又止的情形,他感受到了“我”受了委屈,却不愿直接说出(2分);表现子网父亲说话时复杂的情感,体现了父亲对“我”的担心、牵挂和疼爱等情感(2分)。
20.结构上:收束全文,与题目(或“第③段”)照应。(1分,答出一点即可)
内容上:深化中心,赞美细腻而深沉的父爱,表达了“我”对家的珍惜和对父亲的思念、感激之情。(2分)
猜你还感兴趣的:
浏览量:3
下载量:0
时间:
方程式计算题是化学考试中较难的题目,平时一定要多练习,才能在解题时有相应的思路。下面是由读文网小编带来的初3化学方程式计算题及答案,希望对你有所帮助。
一 选择题
1—5 BCCAC 6—8 BBA
二 配平下列的各个化学反应的方程式:
(1) 2KMnO4 加热 K2MnO4 + MnO2 + O2↑
(2) 2Al + 3CuSO4 Al2(SO4)3 + 3Cu
(3) Zn + 2HCl ZnCl2 + H2↑
(4) Al2O3 + 3H2SO4 Al2(SO4)3 + 3H2O
(5) Fe2(SO4)3 + 6NaOH 3Na2SO4 + 2Fe(OH)3
(6) 2Fe(OH)3 + 3H2SO4 Fe2(SO4)3 + 6H2O
(7) CH4 + 2O2 点燃 CO2 + 2H2O
(8) C + CO2 高温 2CO
(9) 4NH3 + 5O2 催化剂 4NO + 6H2O
(10) 3CO + Fe2O3 高温 2Fe + 3CO2
以上就是读文网小编为您整理的初3化学方程式计算题及答案,欢迎收藏。
浏览量:2
下载量:0
时间:
同学们要在考试中展现出自己最好的水平,大家更应该加把劲,努力学习,下面是读文网小编为大家带来的关于中考英语阅读理解总复习题,希望会给大家带来帮助。
A
A long time ago. there was an emperor. He had a beautiful garden. In the garden, there was a little nightingale(夜莺) singing very beautifully.
One day the emperor heard about this little bird's beautiful voice. He asked his guards to bring her to him. As soon as the emperor heard the nightingale's voice, he said, "Put her in a golden cage, so she can stay and sing for me whenever I want to hear her. "
The tittle bird was so unhappy about being kept in the cage that she stopped singing one day. The emperor was very angry. He ordered the scientists in his palace to make a robot bird for him. The bird could sing very beautifully, too. The emperor was pleased.
Soon the robot bird became old. It no longer sang beautiful songs. Just at that time, the emperor became very weak. One morning, while lying in bed, the emperor wanted it to sing once again. But the robot bird couldn't sing any more. Suddenly the nightingale landed on the window. She began to sing her most beautiful song. The emperor was very happy! He became better and better each day.
After the emperor was well,he changed a lot and became kind to his people. From then on, all his people cherished(爱戴) him for his love and kindness.
( )1. Both the nightingale and the robot bird had a beautiful voice.
( )2. The emperor kept the nightingale in a golden cage in order to hear her sing at any time.
( )3. The nightingale was very happy after she was kept in the golden cage.
( )4. The emperor was not satisfied with the robot bird at first.
( )5. The emperor learnt from the nightingale what love and kindness was.
B
In the year 2050, there will be different kinds of materials for clothes. Special materials will keep the clothes clean for ever. They will never get dirty or wear out. We will have less work because we won’t have to wash them. So we can save water and money. And children won’t worry about what to wear to school every day. They won’t go to school. They’ll stay at home in front of their computers to study. They can wear their favorite “Saturday clothes” every day. It will be fun. Do you think so? What do you think school clothes and school life will be like in 2050?
( )6. Maybe we wash clothes in the year 2050.
A. didn’t B. needn’t C. mustn’t D. won’t be allowed to
( )7. Why won’t the children go to school?
A. because they’ll play at home. B. because they hate to go to school.
C. because they’ll study on the Internet. D. because they’ll wash clothes to make money.
( )8. Will the clothes get dirty in the year 2050?
A. No, it won’t. B. Yes, they will. C. Yes, it will. D. No, they won’t.
( )9. In the year 2050, the clothes will not for ever
A. wear out or get dirty B. wear well C. be thinner and thinner D. be fantastic
( )10. From the passage,which of the following is NOT true?
A. There will be different kinds of materials for clothes .
B. The children can wear their favorite clothes.
C. The children always worry about what to wear .
D. The children can study at home in front of their computers.
C
At East China University of Science and Technology,students will get a coupon (优惠券) if they eat up their food.Students can collect coupons and exchange them for small gifts, such as books, magazines, mobile phone covers and hand warmers.
"It's been such a surprise," said Liang Zhaoyun, 19, a student at the university in Shanghai. "It has given us one more motivation to finish our food. "
The measure is part of a national "eat-up" campaign(行动) which is organized by students to deal with food waste on campuses(校园).
Why only on campuses, you might ask? Because according to a report by Xinhua News Agency, students waste twice as much food as the national average(平均).
The campaign on campus food waste is receiving attention across the country.
"The aim of the campaign is not only to encourage students to finish their food. We hope it can also encourage students to choose a more environment-friendly and healthy lifestyle," said Tao Siliang, secretary of the Youth League Committee at Shanghai University.
But some school food is poorly prepared, so students do not like to finish it all. Some schools have taken notice of this and they are taking measures to improve it.
"I'm glad that we've reduced food waste since the 'eat-up' campaign began. But if we call on students to waste less food, we should also improve the service and food standard on campuses." said Tao.
( )11. From Paragraph 1 we know that the students will get a coupon .
A. when they eat school food B. after they exchange gifts
C. if they finish all their food D. if they collect the waste
( )12. The under lined word "motivation" in Paragraph 2 means in Chinese.
A. 动力 B. 机会 C. 试验 D. 条件
( )13. The "eat-up" campaign is carried out on campuses because ________.
A. students get a good education B. schools offer small gifts
C. students waste too much food D. school food is more delicious
( )14. The purpose of the campaign is mainly to ________ .
A. improve the school food standard B. encourage a greener and healthier lifestyle
C. receive attention from the society D. further improve the service in universities
( )15. The best title for this passage may be _______.
A. Enjoy Your Food! B. Reduce Waste on Campus
C. Meals in Universities. D. "Eat-up" Campaign on Campus
D
Qi Haoran, a Junior 1 student, was quite busy over the past winter vacation – and not just with homework. Qi, together with 10 other classmates made a volunteer group to call on people to join the Clean Your Plate Campaign (“光盘行动”).
The 11 students went to many restaurants and told people the importance of saving food. “Excuse me, do you know that 950 million people around the world still haven’t got enough to eat? Please don’t waste food.” They would say this kind of thing hundreds of times every day.
The Clean Your Plate Campaign began on the Internet in January. It calls on people to reduce food waste.
China in these years had serious problems with wasted food. CCTV reported in January that the food Chinese people waste every year is enough to feed 200 million people for a year.
Chinese people are well known for being hospitable (好客的) and generous(大方的). Many even feel that they lose face if their guests have eaten all the food.
Luckily, the campaign has got the support of many. In a restaurant in Xinjiang, the owner give the guests who have eaten all that they ordered a sticker (贴花). People can enjoy a free meal when they have 10 stickers. More than 750 restaurants in Beijing have begun to offer smaller dishes and encourage their guests to take leftovers (剩饭剩菜) home.
To reduce food waste is a big task, and it needs time. It’s important that everyone does their bit, just like Qi. Did you finish your meals today?
( )16. What did the 11 students do in the winter vacation?
A. The helped each other with homework. B. They opened a restaurant together.
C. They volunteered for a campaign. D. They collected money from customers in restaurants.
( )17. In this passage the underlined word “call on ” means ______.
A. 打电话 B.号召 C.拜访 D. 叫喊
( )18. The Clean Your Plate Campaign calls on people to _____.
A. do volunteer work B. work part time in restaurants
C. cut down on food waste D. wash your plates after dinner
( )19. From Paragraphs 4-5, we learn that _____.
A. wasting food is a serious problem in China
B. Chinese people waste the most food in the world
C. Chinese people want to show off that they are rich
D. most Chinese people are afraid of losing face at the table
( )20. What did the restaurant in Beijing do to support the campaign?
A. The owner would have dinner with those who had eaten up their food.
B. It offered a free meal to the guests who had finished all their food ten times.
C. It gave stickers to the guests who ordered small dishes.
D. It encouraged customers to take leftovers home.
浏览量:3
下载量:0
时间:
化学方程式是化学的基础,是许多化学实验得出的结论。下面是读文网小编为您带来的高考必备化学方程式,希望对大家有所帮助。
1. 氯气与金属铁反应:2Fe + 3Cl2 点燃 2FeCl3
2.氯气与金属铜反应:Cu + Cl2 点燃 CuCl2
3.氯气与金属钠反应:2Na + Cl2 点燃 2NaCl
4.氯气与水反应:Cl2 + H2O = HCl + HClO
5.次氯酸光照分解:2HClO 光照 2HCl + O2↑
6. 氯气与氢氧化钠溶液反应:Cl2 + 2NaOH = NaCl + NaClO + H2O
7.氯气与消石灰反应:2Cl2 + 2Ca(OH)2 = CaCl2 + Ca(ClO)2 + 2H2O
8.盐酸与硝酸银溶液反应:HCl + AgNO3 = AgCl↓ + HNO3
9. 漂白粉长期置露在空气中:Ca(ClO)2 + H2O + CO2 = CaCO3↓ + 2HClO
10.氮气与氧气在放电下反应:N2 + O2 放电 2NO
11. 一氧化氮与氧气反应:2NO + O2 = 2NO2
12. 二氧化氮与水反应:3NO2 + H2O = 2HNO3 + NO
13二氧化硫与氧气在催化剂的作用下反应:2SO2 + O2 催化剂 2SO3
14. 三氧化硫与水反应:SO3 + H2O = H2SO4
16.氨气的实验室制取:2NH4Cl + Ca(OH)2 △ CaCl2 + 2H2O + 2NH3↑
17.氯气与氢气反应:h) 硫酸铵与氢氧化钠反应:(NH4)2SO4 + 2NaOH △ 2NH3↑ + Na2SO4 + 2H2O i)
18.SO2 + Cl2 + 2H2O = 2HCl + H2SO4
19. SO2 + 2H2S = 3S + 2H2O (13) S及其化合物的化学反应方程式 a) SO2 + CaO = CaSO3 b) SO2 + 2NaOH = Na2SO3 + H2O
20.SO2 + Ca(OH)2 = CaSO3↓ + H2O
浏览量:2
下载量:0
时间:
背诵方程式在一定程度上也是为了更理解化学实验的过程与结论。下面是读文网小编为您带来的高考化学常考方程式,希望对大家有所帮助。
1.四羟基合氯酸钠与盐酸(少量)的反应Na[Al(OH)4]+HCl==== Al(OH)3↓+NaCl+H2O
2.氢氧化铝与盐酸的反应Al(OH)3+3HCl==== AlCl3+3H2O
3.四羟基合氯酸钠与盐酸(过量)的反应Na[Al(OH)4]+4HCl==== AlCl3+NaCl+4H2O 4.四羟基合氯酸钠与氯化铝的反应3Na[Al(OH)4]+AlCl3==== 4Al(OH)3↓+3NaCl
5.向四羟基合氯酸钠中通入过量二氧化碳Na[Al(OH)4]+CO2==== Al(OH)3↓+NaHCO3
6.铜在潮湿空气中被腐蚀2Cu+O2+H2O+CO2==== Cu2(OH)2CO3
7.铜与氧气的反应2Cu+O2==== 2CuO
8.铜与氯气的反应Cu+Cl2==== CuCl2
9.铜氧化在高温下转化4CuO==== 2Cu2O+O2↑
10.硫酸铜与水的反应CuSO4+5H2O==== CuSO4+5H2O
11 Na2SiO3溶液中通入少量CO2气体:SiO32-+ CO2+ H2O H2SiO3↓+ CO32-
12 Si与NaOH溶液反应:Si + 2 OH- + 2H2O SiO32- + 2H2↑
13 SO2通入氯水中,氯水褪色:SO2 + Cl2 + 2H2O2H++SO42-+2 Cl-
14 SO2通入溴水中‘溴水褪色’:SO2 + Br2 + 2H2O2H++SO42-+2 Br-
15 氨水中滴加稀盐酸:NH3•H2O +H+==NH4++H2O
16 向Na2CO3溶液中滴入几滴稀盐酸(少量):H+ + CO32- =HCO3一
17 向Na2CO3溶液中滴入过量稀盐酸:2H+ + CO32- =CO2↑+ H2O
18 向Na2SO3溶液中滴入几滴稀盐酸(少量):H+ + SO32- =HSO3一
19 向Na2SO3溶液中滴入过量稀盐酸:2H+ + SO32- =SO2↑+ H2O
20 向Na AlO2溶液中滴入几滴稀盐酸(少量):AlO2-+H2O +H+ = Al(OH)3↓
浏览量:3
下载量:0
时间:
化学方程式是所有化学考试的重要组成部分。下面是读文网小编为您带来的高考常见化学方程式,希望对大家有所帮助。
1.亚硫酸与氧气的反应2H2SO3+O2==== 2H2SO4
2.亚硫酸钠与氧气的反应2Na2SO3+O2==== 2Na2SO4
3.浓硫酸与铜的反应 2H2SO4(浓)+Cu==== CuSO4+SO2↑+2H2O
4.浓硫酸与碳的反应 2H2SO4(浓)+C==== CO2↑+2SO2↑+2H2O寿
5.工业制备硫酸(初步) 4FeS2+11O2==== 8SO2+2Fe2O3
6.实验室制备硫酸(初步) Na2SO3+H2SO4(浓)==== Na2SO4+SO2↑+H2O
7.硫化氢(少量)与氢氧化钠的反应H2S+2NaOH==== Na2S+2H2O
硫化氢(过量)与氢氧化钠的反应H2S+NaOH==== NaHS+H2O
8.硫化氢(少量)与氨气的反应H2S+2NH3==== (NH4)2S
硫化氢(过量)与氨气的反应H2S+NH3==== NH4HS
9.硫化氢与氧气(不足)的反应2H2S+O2==== 2S↓+2H2O 2H2S+O2==== 2S+2H2O 硫化氢与氧气(充足)的反应2H2S+3O2==== 2SO2+2H2O
10.硫化氢与氯气的反应H2S+Cl2==== 2HCl+S↓
11.硫化氢与浓硫酸的反应 H2S+H2SO4(浓)==== S↓+SO2↑+2H2O
12.硫化氢的制备FeS+H2SO4==== FeSO4+H2S↑
13.电解饱和食盐水(氯碱工业) 2NaCl+2H2O==== 2NaOH+H2↑+Cl2↑
14.电解熔融状态氯化钠(制单质钠) 2NaCl==== 2Na+Cl2↑
15.海水制镁(1) CaCO3==== CaO+CO2
(2) CaO+H2O==== Ca(OH)2
(3) Mg2++2OH2-==== Mg(OH)2↓
(4) Mg(OH)2+2HCl==== MgCl2+2H2O
(5) MgCl2==== Mg+Cl2↑
16.镁在空气中燃烧(与氧气的反应) 2Mg+O2==== 2MgO
(与氮气的反应) 3Mg+N2==== Mg3N2
(与二氧化碳的反应) 2Mg+CO2==== 2MgO+C
17.镁与氯气的反应Mg+Cl2==== MgCl2
18.镁与水的反应Mg+2H2O==== Mg(OH)2+H2↑
19.镁与盐酸的反应Mg+2HCl==== MgCl2+H2↑
20.镁与氢离子的反应Mg+2H+==== Mg2++H2↑
浏览量:3
下载量:0
时间:
初一需要掌握的知识点有哪些呢?接下来是读文网小编为大家带来的关于初一数学上册一元一次方程知识点,希望会对大家有所帮助。
1.等式与等量:用"="号连接而成的式子叫等式.注意:"等量就能代入"!
2.等式的性质:
等式性质1:等式两边都加上(或减去)同一个数或同一个整式,所得结果仍是等式;
等式性质2:等式两边都乘以(或除以)同一个不为零的数,所得结果仍是等式.
3.方程:含未知数的等式,叫方程.
4.方程的解:使等式左右两边相等的未知数的值叫方程的解;注意:"方程的解就能代入"!
5.移项:改变符号后,把方程的项从一边移到另一边叫移项.移项的依据是等式性质1.
6.一元一次方程:只含有一个未知数,并且未知数的次数是1,并且含未知数项的系数不是零的整式方程是一元一次方程.
7.一元一次方程的标准形式:ax+b=0(x是未知数,a、b是已知数,且a≠0).
8.一元一次方程的最简形式:ax=b(x是未知数,a、b是已知数,且a≠0).
9.一元一次方程解法的一般步骤:整理方程……去分母……去括号……移项……合并同类项……系数化为1……(检验方程的解).
10.列一元一次方程解应用题:
(1)读题分析法:…………多用于"和,差,倍,分问题"
仔细读题,找出表示相等关系的关键字,例如:"大,小,多,少,是,共,合,为,完成,增加,减少,配套-----",利用这些关键字列出文字等式,并且据题意设出未知数,最后利用题目中的量与量的关系填入代数式,得到方程.
(2)画图分析法:…………多用于"行程问题"
利用图形分析数学问题是数形结合思想在数学中的体现,仔细读题,依照题意画出有关图形,使图形各部分具有特定的含义,通过图形找相等关系是解决问题的关键,从而取得布列方程的依据,最后利用量与量之间的关系(可把未知数看做已知量),填入有关的代数式是获得方程的基础.
11.列方程解应用题的常用公式:
(1)行程问题:距离=速度·时间;
(2)工程问题:工作量=工效·工时;
(3)比率问题:部分=全体·比率;
(4)顺逆流问题:顺流速度=静水速度+水流速度,逆流速度=静水速度-水流速度;
(5)商品价格问题:售价=定价·折·,利润=售价-成本,;
(6)周长、面积、体积问题:C圆=2πR,S圆=πR2,C长方形=2(a+b),S长方形=ab,C正方形=4a,
S正方形=a2,S环形=π(R2-r2),V长方体=abc,V正方体=a3,V圆柱=πR2h,V圆锥=πR2h.
看过初一数学上册一元一次方程知识点的还看了:
浏览量:2
下载量:0
时间:
方程式是高中化学学习重点,但如何记忆数量如此之多的方程式呢?下面是读文网小编为您带来的高考化学方程式速记,希望对大家有所帮助。
1、向氢氧化钠溶液中通入少量CO2 : 2NaOH + CO2 ==== Na2CO3+ H2O离子方程式:CO2 + 2OH- CO32-+ H2O
2、在标准状况下过量CO2通入NaOH溶液中:CO2+NaOH NaHCO3离子方程式:CO2+ OH- HCO3-
3、烧碱溶液中通入过量二氧化硫: NaOH +SO2==NaHSO3离子方程式:OH- +SO2 HSO3-
4、在澄清石灰水中通入过量二氧化碳:Ca(OH)2+ 2CO2══Ca(HCO3)2离子方程式:CO2+ OH- HCO3-
5、氨水中通入少量二氧化碳: 2NH3•H2O+CO2== (NH4)2 CO3+ H2O离子方程式:2NH3•H2O+CO2== 2NH4+ +2H2O
6、用碳酸钠溶液吸收少量二氧化硫 : Na2CO3+ SO2 Na2SO3+ CO2↑离子方程式:CO32-+ SO2 SO32-+ CO2↑
7、二氧化碳通入碳酸钠溶液中:Na2CO3+CO2 +H2O══2 NaHCO3离子方程式:CO32-+ CO2 +H2O══HCO3-
8、在醋酸铅[Pb(Ac)2]溶液中通入H2S气体:Pb(Ac)2+H2S=PbS↓+2HAc离子方程式:Pb(Ac)2+H2S=PbS↓+2HAc
9、苯酚钠溶液中通入少量二氧化碳: CO2+H2O+C6H5ONa→C6H5OH+ NaHCO3离子方程式:CO2+H2O+C6H5O-→C6H5OH+ HCO3-
10、氯化铁溶液中通入碘化氢气体: 2FeCl3+2 HI 2Fe Cl2+ I2+2 H Cl离子方程式:2Fe3++2 H++2I- 2Fe 2++ I2+2 H+
浏览量:3
下载量:0
时间:
方程式永远是化学科目必考考点中的“常青树”。下面是读文网小编为您带来的高考化学常用方程式,希望对大家有所帮助。
1、FeS和稀硝酸反应:FeS+4HNO3══Fe(NO3)3+NO↑+S↓+2 H2O
2、电解饱和食盐水:2 NaCl+2H2O C12↑+ H2↑+2NaOH
3、用石墨电极电解硫酸铜溶液:2CuSO4+2H2O O2↑+2Cu+ 2H2SO4
4、醋酸加入氨水: CH3COOH+NH3•H2O CH3COONH4+H2O
5、氢氧化镁加入醋酸: Mg(OH)2+2CH3COOH (CH3COO)2Mg+2H2O
6、在硫酸铜溶液中加入过量氢氧化钡溶液:
CuSO4+ Ba(OH)2══Cu(OH)2↓+ BaSO4↓
7、石灰乳与海水制取氢氧化镁:MgCl2+Ca(OH)2══Mg(OH)2↓+ CaCl2
8、少量氢氧化钙溶液与碳酸氢钙溶液混合:w.w.w.k.s.5.u.c.o.m
Ca(HCO3)2+ Ca(OH)2 2CaCO3↓+2H2O
9、向Ca(HCO3)2溶液中加入足量的氢氧化钠溶液:
Ca(HCO3)2+ 2NaOH══CaCO3↓+ Na2CO3+2 H2O
10、少量氢氧化钙溶液与碳酸氢钠溶液混合:Ca(OH)2+ 2NaHCO3══CaCO3↓+ Na2CO3+2 H2O
11、碳酸氢镁溶液中加入过量的澄清石灰水:
Mg(HCO3)2+ 2Ca(OH)2══2CaCO3↓+ Mg(OH)2↓+ 2H2O
12、氢氧化钡溶液和碳酸氢镁溶液反应:
Mg (HCO3)2 + Ba(OH)2 Mg(OH)2↓+ BaCO3↓+2H2O
13、向碳酸氢镁溶液中加人过量氢氧化钠:
Mg (HCO3)2+ 4NaOH Mg(OH)2↓+2 Na2CO3+2H2O
14、NH4HCO3溶液与过量的NaOH溶液反应:
NH4HCO3+2NaOH(过量)══Na2CO3+ NH3↑+2 H2O
15、向NH4HSO4稀溶液中逐滴加入Ba(OH)2稀溶液至刚好沉淀完全
NH4HSO4+ Ba(OH)2══BaSO4↓+ NH3•H2O+ H2O
16、碳酸氢铵溶液中加入足量氢氧化钡溶液:
NH4HCO3+ Ba(OH)2══BaCO3↓+ NH3↑+ 2H2O
17、在亚硫酸氢铵稀溶液中加入足量的氢氧化钠稀溶液:
NH4HSO3+ 2NaOH Na2SO3+ NH3•H2O+ H2O
18、硫酸氢钠溶液中加入氢氧化钡溶液至溶液pH=7:
2Na HSO4+ Ba(OH)2══Na2 SO4 +BaSO4↓+2 H2O
19、硝酸铝溶液中加入过量氨水: Al(NO3)3+ 3NH3•H2O === Al(OH)3↓+ 3NH4NO3
20、明矾溶液中加入过量的氨水:
2KAl(SO4)2+ 6NH3•H2O 2Al(OH)3↓+ K2 SO4+ 3(NH4)2 SO4
浏览量:3
下载量:0
时间: