(每小題2分,共6分)請回答有關(guān)電解水的問題
(1)右圖為通電分解水的簡易裝置,如果用VA和VB分別表示試管A和試管B中生成氣體的體積,則VA:VB約等于     。理論上應(yīng)等于此比例,實(shí)際上常大于此比例,原因之一是___________________________________

(2)A試管中電極連接的電池的_______極,B中產(chǎn)生的氣體是_______
(3)該實(shí)驗(yàn)?zāi)茏C明的結(jié)論是___________________________________

(1)2:1  合理給分  (2)負(fù)  O2    (3)由氫,氧元素組成。

解析試題分析:依據(jù)所學(xué)化學(xué)知識和實(shí)驗(yàn)經(jīng)驗(yàn)來解答。
根據(jù)“正氧負(fù)氫,氫二氧一”,結(jié)合圖示可推出:由于A中氣體體積較多,所以應(yīng)該是氫氣,則A試管中的電極連接的電池的負(fù)極;B試管中氣體體積少,所以應(yīng)該是氧氣,則B試管中電極連接的電池的正極;由于氫氣和氧氣的體積比為2:1,則VA:VB約等于2:1,由于氧氣是不易溶于水,氫氣是難溶于水,所以氧氣在水中的溶解的量較大些,因此實(shí)際上常大于此比例。
因?yàn)榛瘜W(xué)反應(yīng)前后元素的種類不變,而反應(yīng)生成的氫氣是由氫元素組成的,氧氣是由氧元素組成的,由此可知,水是由氫元素和氧元素組成的。
考點(diǎn):電解水實(shí)驗(yàn)
點(diǎn)評:解答本題的關(guān)鍵是明確電解水的現(xiàn)象,可以用“正氧負(fù)氫,氫二氧一”來分析解答。

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(每小題2分,共6分)請回答有關(guān)電解水的問題

(1)右圖為通電分解水的簡易裝置,如果用VA和VB分別表示試管A和試管B中生成氣體的體積,則VA:VB約等于      。理論上應(yīng)等于此比例,實(shí)際上常大于此比例,原因之一是___________________________________

(2)A試管中電極連接的電池的_______極,B中產(chǎn)生的氣體是_______

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