Chem question

知識就是力量

2010-01-16 11:32 pm

A dilute aqueous solution of acid A is allowed to react with sodium carbonate solution, and effervescence occurs.
(i) Explain why there is effervescence.
(ii) Write an equation for the reaction of acid A and sodium carbonate in aqueous solution.

回答 (1)

老爺子

2010-01-17 12:47 am

✔ 最佳答案

(i)
When dissolved in water, acid A is ionized to give hydrogen ions. The reaction between hydrogen ions and carbonate ions (formed from dissociation of sodium carbonate in water) gives colourless bubbles of carbon dioxide gas.

(ii)
Ionic equation: 2H^+(aq) + CO3^2-(aq) → H2O(l) + CO2(aq)

Full equation:
If acid A is monobasic, denote its chemical formula as HX.
2HX(aq) + Na2CO3(aq) → 2NaX(aq) + H2O(l) + CO2(g)
If acid A is dibasic, denote its chemical formula as H2Y.
H2Y(aq) + Na2CO3(aq) → Na2Y(aq) + H2O(l) + CO2(g)
If acid A is tribasic, denote its chemical formula as H3Z.
2H3Z(aq) + 3Na2CO3(aq) → 2Na3Z(aq) + 3H2O(l) + 3CO2(g)

2010-01-16 16:47:54 補充：
參考資料：老爺子

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