module 5　a lesson in a lab

精品文档2016全新精品资料全新公文范文全程指导写作独家原创1/4MODULE5ALESSONINALABMMODULE5ALESSONINALAB话题导入人类从日常生活到宇宙探索都离不开科学技术。如果没有科学的发展,我们将仍然处于愚昧无知的原始状态,科学技术是第一生产力,它推动了社会经济、文明的发展,使我们人类成为了宇宙的主人。作为中学生,我们应该以“八荣八耻”中的“以崇尚科学为荣、以愚昧无知为耻”为行为准则,把智慧和热情投入到科学研究和探索中。背景资料什么是铁铁位于周期表第四周期第族。元素符号为FE,原子序数为26,是一种重要的过渡元素。光亮的银白色金属,密度786GCM3,熔点1535,沸点2750。纯铁的抗蚀力相当强,但通常的铁都含有碳和其他元素,因而使它的熔点降低,抗蚀力也减弱。铁有延展性和导热性，也能导电。但导电性比铜、铝都差。铁能被磁体吸引,在磁场作用下,铁自身也能产生磁性。铁为什么会生锈铁放的时间长了就会生锈。铁容易生锈,除了由于它的化学性质活泼以外,同时与外界条件也有很大关系。水分是使铁精品文档2016全新精品资料全新公文范文全程指导写作独家原创2/4容易生锈的物质之一。然而,光有水也不会使铁生锈,只有当空气中的氧气溶解在水里时,氧在有水的环境中与铁反应,才会生成一种叫氧化铁的东西,这就是铁锈。铁锈是一种棕红色的物质,它不像铁那么坚硬,很容易脱落,一块铁完全生锈后,体积可胀大8倍。如果不除去铁锈,这海绵状的铁锈特别容易吸收水分,铁也就烂得更快了。引入型阅读CHEMICALCHANGEANDPHYSICALCHANGETHEREARETWOKINDSOFCHANGESCHEMICALCHANGEANDPHYSICALCHANGEINACHEMICALCHANGE,THEREISALWAYSANEWSUBSTANCEFORMEDBREAKINGUPWATERINTOHYDROGENANDOXYGENISACHEMICALCHANGEINEACHOFTHECHEMICALCHANGEATLEASTONENEWSUBSTANCEISFORMEDACHANGEISNOTACHEMICALCHANGEIFITDOESNTFORMANEWSUBSTANCEPHYSICALCHANGESAREVERYCOMMON,TOOTHEREAREMANYEXAMPLESYOUCANMAKEAPHYSICALCHANGEBYTEARINGAPIECEOFPAPERINTWO,ORBYCUTTINGAPIECEOFIRONWITHLATHEHEREPAPERISSTILLPAPER,ANDTHEIRONISSTILLIRONANOTHERWAYOFMAKINGPHYSICALCHANGEISDISSOLVINGSOMETHI精品文档2016全新精品资料全新公文范文全程指导写作独家原创3/4NGINWATERWHENYOUDISSOLVESALTINWATER,THESALTDISAPPEARSYOUMAYTHINKTHATANEWSUBSTANCEHASBEENFORMEDBUTREALLYTHEREISNONEWSUBSTANCETHESALTISSTILLSALTYOUCANSTILLTASTEITSOTHEDISSOLVINGOFANYTHINGISAPHYSICALCHANGEWHENWATERFREEZES,THECHANGEISALSOAPHYSICALONETHEWATERCHANGESFROMLIQUIDTOSOLIDBUTITISSTILLTHESAMESUBSTANCETHATISWHYTHEFREEZINGOFANYTHINGISAPHYSICALCHANGE1ITISNOT_IFANEWSUBSTANCEISNOTFORMEDINTHECHANGEAAPHYSICALCHANGEBACHEMICALCHANGECCHANGEOFSTATEDACHANGE2THEDISSOLVINGOFSALTINWATERIS_AAPHYSICALCHANGEBACHEMICALCHANGECHYDROGENANDOXYGENDBREAKINGUP3THECHANGEOFTHETHREESTATESOFWATERIS_AACHEMICALCHA