chem ionic equation

First,

2NaOH(aq)+H2SO4(aq)->Na2SO4(aq)+2H2O(l)

You have to find the spectator ions first which are maintain in the same physical state and chemical state before or after the reaction.

In the reaction, sodium ions and sulphate(II) ions are spectator ions.

Therefore the ionic equation is 2OH-(aq)+H2(aq)->2H2O(l)


Second,

Suppose several compounds:

NaOH
CaCO3
NaHCO3

Determine their physical state by under room temperature

NaOH --> it can be solid or aqueous
CaCO3 --> it is always in solid state because it is not soluble in water.
NaHCO3 --> it is always in solid state because it is not solution in water.


Thirdly,
During the reaction of metals and dilute acids,

the solution gives out heat.

How about the reaction of:
1.Metal oxide + acid
2.Metal hydroxide + acid
3.Metal carbonate + acid
4.Metal hydrogencarbonate + acid

The reaction will give out heat when it is an exothermic reaction. In the question of 1 to 4 , all of them are exothemic reaction, therefore they all give out heat.

Fourth,

the ionic equation is:

Na2CO3(s)+2H+(aq)->2Na+(aq)+CO2(g)+H2O(l)

When it is called acid, it must contain hydrogen ions when in aqueous state. The hydrogen ions must be provided by the citric acid and sodium ions is provided by Na2CO3 which the Na2CO3 is dissolve in water from the acid and produce sodium ions.

The structure of citric acid:

圖片參考：http://imgcld.yimg.com/8/n/HA00132844/o/701112100076013873409690.jpg



Fifth,

calcium compounds are having various of properties. Calcium suphate(II) is insoluble in water, calcium hydroxide is slightly soluble in water, calcuim chloride is soluble in water. It is different to tell you the stable solubility of calcium compounds.

For lead, except lead(II) sulphate and lead(II) halides, most of the lead compunds are soluble in water.

no correct ans in q 1...

CaCO3 is insoluble in water, so they do not dissolve instead.
In fact, NaHCO3 is soluble in water. All salts containing HCO3^- ions are soluble in water. But it can exist as solid in nature when there is no water.

2011-12-12 22:54:57 補充：
3. (1),(2) are neutralization -> exothermic giving out heat.
(3),(4) are similar to neutralization -> also exothermic that give heat.

4. Acid usually contains hydrogen ions, thus reacting with CO3^2- in Na2CO3 to form CO2.

2011-12-12 22:55:42 補充：
structure of citric acid is complicated, just remember there are H^+ in the acid and exhibits the acidic property to react with Na2CO3.

2011-12-12 22:57:04 補充：
5. just refer to your books, those exceptions for insolubility need to be revised and memorized.

2011-12-12 22:59:36 補充：
1.You know only H^+ in H2SO4 can react with OH^- in NaOH
therefore, just directly write down: H^+ + OH^- --> H2O
It is a waste of time for you to look for all spectator ions like Na^+ and SO4^2-.

First,
2NaOH(aq)+H2SO4(aq)->Na2SO4(aq)+2H2O(l)

2Na+2OH-(aq) + 2H+SO4-(aq) -> 2Na+SO4-(aq) + 2H+2OH-(l)

Second,
NaOH - sodium hydroxide - can be aqueous and solid
CaCO3 - calcium carbonate - always solid because it forms a white precipitate when dissolved in water
NaHCO3 - sodium hydrogen carbonate(or sodium bicarbonate) - always solid because it forms a white precipitate when dissolved in water
They will probably tell you in the question.

Third,
During the reaction of metals and dilute acids, the solution gives out heat.
How about the reaction of:
1.Metal oxide + acid -->exothermic
2.Metal hydroxide + acid -->exothermic because of neutralisation reaction
3.Metal carbonate + acid -->exothermic
4.Metal hydrogencarbonate + acid-->exothermic

Forth,
Look at the formula of anhydrous sodium carbonate: Na2SO3.
well, of course it would form 2Na+ ions.
all acids have hydrogen in it (except for Lewis acid).
by the way, the formula for citric acid is C6H8O7.

Fifth,
all nitrates can dissolve in water.
All sodium and potassium salts can dissolve in water.
the compounds you typed has poor solubility in water.