電池如何把chemical energy轉變成electrical energy??

化學能是指某兩或以上物質經反應釋放的能量總和(包括熱能/聲能/電能/光能...)
在電池中誘發電能的化學反應是主要由正電極,負電極,電解質三種標準設備組成.
以鋅碳電池(即是一般的乾電池)為例:
電池正電極是一支被碳粉和氧化錳(IV)混合物所包圍的碳棒,電池的外殼(不計保護層)由鋅造成,是電池的負電極,電解質是糊狀的氯化銨.
當鋅碳電池被連接在閉合電路上,反應隨即開始:
首先鋅被氧化成鋅離子並放出電子,電子由負電極經外電路進入正電極,電子進入後和銨離子反應成氨氣和氫氣,而氧化錳(IV)的作用就是把兩種氣體吸收,免得電池因氣體彭脹而破裂.電子的出入循環成了電流,把電燈泡接上便有光和熱,即是說,電池中反應的化學能生成電能,電燈泡把電能轉換成光能/熱能.所以要有電能的使用,電能才在過程中特顯有用的角色.當鋅外報完全氧化,不能再放出電子,這電池的使用壽命到了.當然,最外層是由密封式的鋼造成,免得漏出有毒的化合物.

Let me give you an example
Zinc electrode is placed into a beaker of zinc sulphate solution and copper electrode is placed into another beaker of copper (2) sulphate solution. The electrodes is connected by an external wire and the two ends of a salt bridge dipped into the two solutions. As zinc is at a higher position in the electrochemical series, therefore zinc loses electrons readily than copper. Electrons from zinc flow through the external conducting wire and go to the copper. Cu2+ gains electrons and stick onto the copper electrode. The mass of zinc electrode decreases and the mass of copper electrode increases. So, chemical energy changes to electrical energy.