Ionic equation

Question

Calcium and dilute supluric acid

Ca(s)+H2SO4(aq)====＞CaSO4(s) + H2(g)

Am I right?


Remark:Calcium + dilute supluric acid and the product is insoluble in water.

However, SO4 has changed the state after the reaction, from (aq) to (s).Do I necessary to consider this?

Answer 1

Your equation is right :
Ca(s) + H2SO4(aq) → CaSO4(s) + H2(g)

There are 2 points to be noted :

1. The CaSO4 formed may coat on the surface of Ca, and thus the reaction will stop before the completion of the reaction. However, if the reaction rate is rapid enough, the rapidly formed hydrogen gas will make the CaSO4 solid detach from the surface of Ca, and the reaction thus completes. No matter the reaction completes or not, the reaction goes on for a period of time, and the equation is valid.

2. In writing ionic equation, only separated ions in aqueous solution are written in ionic form. CaSO4(s) cannot be written as separate ions because its ions are well arranged and are not separated Therefore, the ionic equation for this reaction is :
Ca(s) + 2H^+(aq) + SO4^2-(aq) → CaSO4(s) + H2(g)

Answer 2

I think you are wrong.
As you have mentioned, there would be an insoluble layer of calcium sulphate formed on the calcium solid in the reaction of calcium and dilute sulphuric acid . So, there are no observable change in the reaction. You do not need to consider some of the sulphate ions had been changed into solid state.
Therefore, it should be:
[Ca(s)+H2SO4(aq)→No apparent reaction] for chemical equation.
There are no ionic equations need to write for this reaction.
You can write [No apparent reaction] directly.

Answer 3

應該係:
ca+2h(正)--->ca(2正)+h2
phy state可以唔寫,
寫左唔加分,寫錯會扣分

2006-11-16 19:16:46 補充：
佢要ionic wo,so4一直都係2-,所以係唔洗寫~