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题型示例一 :基本概念的认识【例 1】 对于反应 :4NH3(g) + 5O2 (g) =4NO(g) +6H2 O(g) ,在 2L的密闭容器中进行 1min后 ,NH3减少了 0 .1 2mol,表示该时段的反应速率中 ,正确的是A .v (NO) :0 .0 0 1mol·L- 1·s- 1B .v (H2 O) :0 .0 0 2mol·L- 1·s- 1C .v (NH3) :0 .0 0 2mol·L- 1·s- 1D .v (O2 ) :0 .0 0 1 2 5mol·L- 1·s- 1解析 :先根据概念求出用NH3表示的反应速率 ,v(NH3) =0 .1 2mol2L× 60s =0 .0 0 1mol· (L·s) - 1,然后根据 :v(NH3) ∶v(O2 ) ∶v(NO)∶v(H2 O) =4∶5∶4∶6;比较其他物质表示的反应速率… 相似文献
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5-(o-硝基)亚甲基若丹宁分光光度法测定金 总被引：4，自引：0，他引：4
研究了新试剂 5 (o 硝基 )亚甲基若丹宁 (o NBR)与贵金属离子Au(III)的显色反应 ,在pH =4的HAc NaAc缓冲溶液中 ,乳化剂 OP存在下 ,Au(III)与o NBR生成 1∶2的稳定络合物 ,λmax=4 2 0nm ,ε =5 .0 3× 10 4L·mol-1·cm-1,金的含量在 0～ 5 0 μg/ 2 5mL范围内符合比尔定律 .方法用于金矿石中痕量金的测定 ,结果满意 相似文献
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1 选择题(1 )市售浓硫酸的质量分数为 98% ,其密度ρ=1 .84 g·mL-1 ,该硫酸的物质量浓度为 ( )。A .0 .1 84mol·L-1 B .1 .84mol·L-1C .1 8.4mol·L-1 D .1 84 .0mol·L-1 (2 )配置某药剂需用 0 .30 0mol·L-1 硫酸溶液 ,欲将2 0 0 0mL0 .1 0 0mol·L-1 硫酸溶液利用起来 ,需取3.0 0mol·L-1 硫酸溶液 ( )与其混合 ,才能配成0 .30 0mol·L-1 硫酸溶液。A .0 .1 4 8mLB .1 .4 8mLC .1 4 .8mLD .1 4 8mL (3)已知水的Kf=1 .86K·kg·mol·L-1 ,若将 2 .76 g甘油溶于 2 0 0g水中 ,测得凝固点下降 0 .2 79K ,则甘… 相似文献
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把CO2 通入饱和Na2 CO3溶液有没有白色NaH CO3沉淀析出 ,对于这个问题 ,有两种截然不同的观点。一种意见认为 :理论上Na2 CO3溶液是个碱 ,有资料显示 :C(Na2 CO3) =1.32mol/L ,14 % ,pH =11.76(更不用说是饱和Na2 CO3溶液了 :2 0℃时 ,17.7% ;2 5℃时 2 5 % ) ;通常室温时 ,H2 CO3饱和溶液浓度C(H2 CO3) =0 .0 4mol/L ,pH =3.88。当CO2 持续通入Na2 CO3饱和溶液时 ,生成溶解度比Na2 CO3要小得多的NaHCO3是理所当然的 (NaHCO32 0℃时 9.6g/10 0g水 ,2 5℃时 10 .35g/ 10 0g水 ;Na2 CO32 0℃时 2 1.5g/ 10 0g水 ,30℃时 3… 相似文献
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一、审题不慎审题是解题的前提,“磨刀不误砍柴工”,审题不能急于求成,马虎草率,必须理解题意,注意题目中关键字、词、句·从历年的考生考试情况来看,审题常见错误有:1·不看全题,断章取义;2·粗心大意,一掠而过;3·误解题意,答非所问;4·审题不透,一知半解·因此要加强审题训练,做到既快又准·例1标准状况下,往100mL0·2mol/L的FeBr2溶液中通入一定体积的Cl2充分反应后,溶液中有50%的Br-被氧化,则通入的氯气的体积是()(A)0·224L(B)0·336L(C)0·448L(D)0·672L解析:由于2Br-+Cl2=Br2+2Cl-,根据题意,有50%的Br-被氧化,即有0·02mol… 相似文献
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毕金钵 《上海大学学报(英文版)》2004,(3)
1 Introduction ItisknownthattherehavebeenmanymethodssuchasHirota’sbilinearmethod[1 3] ,B cklundtrans formation (BT) ,theinversescatteringtransform[4 ] ,andsoonforfindingthesolutionsofthesolitonequa tions.Inthisletter,weconsidertheexactsolutionsoftheMKdVequationvt+vxxx+6v2 vx=0 (1)bymeansofamodifiedbilinearBT .Theoriginalver sionofbilinearBT[5] isDxf·g =-λf g ,(Dt+3λ2 Dx+D3x) f·g =0 ,(2 )whereλisarealnumberandthebilinearoperatorDisdefinedasDmt Dnxf·g = (t-t′) m(x-x… 相似文献
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王迅 《天津大学学报(英文版)》2004,10(1)
Thecriticalheatflux (CHF)intheforcedconvec tiveboilingwithawalljethasbeenstudied.KattoandIshii[1 ] measuredtheCHFofsaturatedwater,R1 1 3 ,andtrichloroethane (ρl/ ρg =2 0 3— 1 60 3)atatmosphericpressureforadownwardfacingplanewalljet,varyingthevelocityufrom 1 .5to 1 5m/sandtheheaterlengthLfrom 1 0to 2 0mm ,andproposedEq.(1 )topredicttheirCHFdata. qcoρghfgu=0 .0 1 6 4(ρl/ ρg) 0 .867(σρlu2 L) 1 / 3 (1 ) KattoandHaramura[2 ] ,further,haveextendedtheirvelocityrangefromu =1 .8t… 相似文献
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CO2 通入Na2 CO3溶液会有NaHCO3沉淀析出吗 ?这是一个问者容易答者难的问题。问者何易呢 ?第一、Na2 CO3溶液显碱性 ,CO2 是微溶于水的酸性气体 ,两者相遇肯定会有NaHCO3生成。第二 ,饱和CO2 水溶液 ,其浓度约为 0 .0 1mol·L- 1 ,pH =3.98;0 .1mol·L- 1 Na2 CO3,c(OH- ) =4.2 2× 1 0 - 3mol·L- 1 ,pH =1 1 .6[即使是Na2 CO3 浓溶液 ,c (Na2 CO3) =1 .32mol·L- 1 ( 1 4% ) ,pH =1 1 .76]两者相遇 ,无疑会发生酸碱反应 ,生成NaHCO3。第三 ,从溶解性考虑 :Na2 CO3 的溶解度( 2 0℃ ,2 1 5 g)。NaHCO3的溶解度 ( 2 0… 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献
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正A One day a pig went to the stable(马棚)to see his good friend,an oldhorse,and was going to stay there forthenight.Night came and it was time forsleep.The pig went into the straw heap(稻草堆)and lay comfortably.A longtime passed,but the horse was stillstanding there and did not move.Thepig asked the horse why he did not go tosleep."Standing like this is the begin-ning ofsleeping,"answered the horse. 相似文献
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《今日中学生》2014,(9)
正1.Any fool can count the seeds in an apple.Only God can count all the apples in one seed.2.Happy families are all alike;every unhappy family is unhappy in its own way.3.Memories are the key not to the past,but to the future.4.Sometimes in the dark you see what you want to see.5.There is a great difference between 相似文献
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《重庆大学学报(英文版)》2014,(2)
正Scope and Policy The Journal of Chongqing University-English Edition(JCQU-E)is a peerreviewed journal publishing research articles in multiple disciplines of science and technology,covering civil and environmental engineering,chemical engineering,biotechnology,mechanical and electrical engineering,computer and data processing,mining,metallurgy,materials science,and interdisciplines thereof. 相似文献