Solubility

[QuarkQuarkQuark2001]

Ionic compound such as sodium chloride is decomposed when it's put in water,

then water molecule "take"one chloride or sodium left.

At this moment, I think the formula is NaH2O or H2OCl, and its properties is changed, am I correct?

 

And why doesn't calcium carbonate act like ammonia which is soluble in water?

 

Buddies Help me

[budullewraagh]

well.....it really isn't NaH2O+ or H2OCl-

the same thing works for H3O+ in that it really isn't H3O+, rather it is H+ and H2O because there's nothing there to form a coordinate covalent bond. So, you actually have Na+, Cl- and 2H2O

 

when you have NH3 dissolve in H2O, you get NH4OH

when you have CaCO3 dissolve in H2O, you get Ca2+, CO32-, H2O, but it is a bit basic since you have Ca(OH)2 and H2CO3 formed in the process. the Ca(OH)2 is more basic than H2CO3 is acidic so the solution becomes basic. that is why you can use carbonates and bicarbonates for neutralizing bases

[QuarkQuarkQuark2001]

well.....it really isn't NaH2O+ or H2OCl-

the same thing works for H3O+ in that it really isn't H3O+' date=' rather it is H+ and H2O because there's [i']nothing[/i] there to form a coordinate covalent bond. So, you actually have Na+, Cl- and 2H2O

 

when you have NH3 dissolve in H2O, you get NH4OH

when you have CaCO3 dissolve in H2O, you get Ca2+, CO32-, H2O, but it is a bit basic since you have Ca(OH)2 and H2CO3 formed in the process. the Ca(OH)2 is more basic than H2CO3 is acidic so the solution becomes basic. that is why you can use carbonates and bicarbonates for neutralizing bases

 

What does nothing mean?

And does NH4OH still have a melting point of 100 degree Celsius?

Thank you

[budullewraagh]

nothing means there is a severe lack of electrons. a coordinate covalent bond is formed when something donates both e- to the bond.

 

actually, NH4OH boils at 36 celcius

[QuarkQuarkQuark2001]

nothing means there is a severe lack of electrons. a coordinate covalent bond is formed when something donates both e- to the bond.

 

actually' date=' NH4OH boils at 36 celcius[/quote']

 

A place without atoms, is it better?

[budullewraagh]

A place without atoms, is it better?

no, i mean there's a severe lack of e- from the H+

H+ is just a floating proton. it would need to be H- to form a coordinate covalent bond

[QuarkQuarkQuark2001]

oh maybe I know

Water molecule just seperate NaCl but never attract the chloride or the sodium ion becoming a part of itself, right?

[budullewraagh]

that is true. the Cl- tend to drift towards the H in H2O. the Na tend to drift towards the other side of the H2O; the O.

[QuarkQuarkQuark2001]

Why do sodium chloride mix with water instead of reacting?

[budullewraagh]

it does react (exothermically) with H2O; the NaCl breaks its bond, and forms Na+ and Cl-

[QuarkQuarkQuark2001]

it does react (exothermically) with H2O; the NaCl breaks its bond, and forms Na+ and Cl-

 

But, the bonds of NaCl is broken, then it should combine with other atoms to form new substance, a chemical change,doesn't it?

Is that combine with atoms only to form new substance,chemical change.

But not combine with molecule to have new chemical change?

The term atom is not replaceable and is unique in chemical change, is it ?

 

After being told by my friends ,

I am trying to write a few more words to ensure that you understand it, friends.

[budullewraagh]

But, the bonds of NaCl is broken, then it should combine with other atoms to form new substance, a chemical change,doesn't it?

actually, when in an aqueous solution, NaCl does not react unless you add some other chemical that would react with NaCl. you see, the bonds between H and O are strong, so the Cl- will not replace the O and the Na+ will not replace the H. despite this, Van Der Waal's forces still do act, and as a result, the NaCl(s) is broken down to form Na+ and Cl- aqueous ions. that is as far as the reaction goes, however. i suppose one could think of it as being similar to a decomposition reaction.

[QuarkQuarkQuark2001]

actually, when in an aqueous solution, NaCl does not react unless you add some other chemical that would react with NaCl. you see, the bonds between H and O are strong, so the Cl- will not replace the O and the Na+ will not replace the H. despite this, Van Der Waal's forces still do act, and as a result, the NaCl(s) is broken down to form Na+ and Cl- aqueous ions. that is as far as the reaction goes, however. i suppose one could think of it as being similar to a decomposition reaction.

 

May I ask further more?I am too young and haven't studied about the decomposition, but I want to learn more.

I know the replacement rule, but for calcium carbonate ,

CaCO3+H2O+CO2--------->H2CO3

It seems it doesn't follow the rule, does there any rule I don't know, would you tell me ?

[budullewraagh]

decomposition is just the reverse synthesis. we all know that Na+Cl->NaCl

that is the synthesis. it also goes in reverse; NaCl->Na+Cl

 

as for your example, i do not believe that that is a working reaction; Ca is much more active than H2, and it certainly has strong intermolecular forces.

[QuarkQuarkQuark2001]

decomposition is just the reverse synthesis. we all know that Na+Cl->NaCl

that is the synthesis. it also goes in reverse; NaCl->Na+Cl

 

as for your example' date=' i do not believe that that is a working reaction; Ca is much more active than H2, and it certainly has strong intermolecular forces.[/quote']

 

 

So may I ask what you would think of the reaction process and the product of my formula?

[budullewraagh]

NaCl --H2O->NaCl(aq)

 

another way of stating this is:

 

NaCl+H2O->Na+(aq) + Cl-(aq)

 

the physical properties of the NaCl have changed, of course since it is dissolved. the chemical properties have changed as well considering wet reactions tend to be faster than dry reactions

[Mr_Mediocre]

Hi again Guys,

 

Na+ forms a solvation sphere around it with water which is co-ordinated to it. Co-ordination bonds are different to covalent bonds. Na+ can have 6 or 7 water molecules in its primary co-ordination sphere. The lone pairs on the oxygen atoms `co-ordinate' to the Na+ cation. There is also a secondary co-ordination sphere which is much more loosely defined and can consist of 12 or more water molecules in dynamic exchange with the surrounding solvent waters.

 

As for Cl-...it is solvated by accepting multiple hydrogen bonds from water molecules. In crystal structures where there is a proliferation of H-bond donors, Cl- usually accepts 3 or 4 H-bonds from either OH or NH groups. In solution, it is a much more dynamic environment and the water molecules participating in H-bonding to Cl- are constantly exchanging with each other as the H-bond interactions between water molecules are a little stronger than those between water and Cl-. This is a hydrogen bonding sphere rather than a co-ordination sphere (like for Na+).

 

Think of the waters as a cushion between ions that would otherwise stick together if there was not enough `cushion' (solvent) to keep them apart.

 

Cheers