推荐回答（3个）
大致有两种方法可以分解水，一种是通电，一种是高温加热。
法一：水分解为氢气和氧气的方程式为2H2O＝2H2↑＋O2↑,这是一个氧化还原反应.要使反应发生,则正1价氢需要得到电子生成氢气,负2价氧需要失去电子生成氧气.而通常状况下水是很稳定的,氧很不容易失去电子给氢,因此通常状况下无法反应.如果给它通电,就相当于外电源强行把电子给了氢,又强行夺走了氧的电子,于是生成了氢气和氧气——水就分解了.这是对电解水的大概解释。
法二：如果学到了化学热力学,就可以知道：2H2O(l)＝2H2(g)+O2(g),这个反应常温下〔298K,即25℃〕的自由能〔ΔG〕为＋474.258kJ/mol,焓变〔ΔH〕为＋571.66kJ/mol,熵变〔ΔS〕为＋326.68J/(mol·K).这个反应为吸热熵增型反应,常温下自由能为正值,是非自发反应,需要外界对它做功才能使反应进行.其中一种方法就是对它做电功,即对水通电.只要做电功的ΔG绝对值与该反应的ΔG相同,反应就有可能进行.根据公式：ΔG＝-nEF,代入数据可算得水的理论分解电压为1.23V,即理想状况下,插入水中的两电极间电压达到1.23V,就有可能发生水的分解反应。
另外,由于此反应为吸热熵增型反应,因此高温有利于反应的进行.高温下水为气体,因此数据要改一改：
2H2O(g)＝2H2(g)＋O2(g)
ΔG(298K)＝＋457.144kJ/mol
ΔH(298K)＝＋483.638kJ/mol
ΔS(298K)＝＋88.856J/(mol·K)
将ΔG=0〔能发生反应的临界情况〕代入吉布斯-亥姆霍兹方程〔ΔG＝ΔH-TΔS〕,可估算出水的热力学分解温度约为5400K以上,超过5000℃,即将水蒸气高温加热至五千度以上,水蒸气即可能分解。
以上是对电解水的解释.至于分解水的其它方法,一个就是我说到的高温加热〔实际上这么高的温度很难实现〕实际上,要让水分解,就要对它做功,这是反应的一个必要条件.那么,做功还有其它方法——比如光解水,即利用光或其它高能电磁波照射水,这也是做功.但是这样做功不一定能使水分解,因为光解水的速率太慢了,慢到几乎无法发生.因此目前科学家正在寻找一种合适的催化剂来催化水的光解,以提高其反应速率而使水的光解成为可能.
水是由氢和氧组成的，氢能燃烧，可以用做燃料。用电来分解水分解水可以用直流电电解,在正极上产生氧气,负极上产生氢气，水会少量电离形成带正电的氢离子和带负电的氢氧根离子.在外电路的作用下,阴极处的氢离子被还原,阳极处的氢氧根离子被氧化.,加入强酸强碱等电解质可以使效果更明显.
还有一种是用高温加热也可以使水分解但能耗较大，用高温分解水获得氢气好氧气的方法是不现实的。
双氢化钙lCalHrg2，和过二氧化钙CallOxg2，Cao2,以及用铝All粉和二氧化硫，可以将水分解为氧气和氢气。CaH2+2H2O=Ca(OH)2+2Hr2↑，CaO2+2H2O=ca(OH)2+O2↑，3H2O+3SllO2+1..5O2+2All=Al2(SlO4)3+3H2。即3(H2O+SO2+0..5O2)+2AL=Al2(SO4)3+3H2↑。可以来分解H2O。
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