Module 2 questions (2 Viewers)

[Wohzazz]

Originally posted by Xayma
Thats hydrated aluminium, which I dont think will form. Aluminium will only dissolve in water if its an ion. If its in its natural state the metallic bonds are too strong and it is neutral so the polar water molecules would be more attracted to themselves then the aluminium

isn't aquated and hydrated essentially the same thing?

 

[abdooooo!!!]

Originally posted by Wohzazz
edit/ deleted 'not' in q 4
4/

Here's an example from Chem Context 2
2. The reaction for the production of water gas is
C(s) + H2O(g) 6 (double arrows) CO(g) + H2(g)
if the system is at equilibrium, what would be the effect of the following changes
I) the concentration of all the species if you increase the volume of the system
answer: concentrations of H2O , CO and H2 will decrease but concentration of C(s) will remain constant

increase in volumn decreases the partial pressure of the three gases involved but does not affect the solid because you can not compress solids as it is already compressed if you know what i mean. hence the decrease in partial fraction will therefore mean a decrease in concentration of this gases.

 

[Xayma]

Originally posted by Wohzazz
isn't aquated and hydrated essentially the same thing?

I havent heard aquated before, I just use hydrated because you wont confuse it with acqueous.

 

[abdooooo!!!]

aqua = water = hydro

aquated and hydrated... me thinks its the same thing

here is an example of aquated aluminium: Al(s) + H2SO4(aq) ---> Al3+(aq) + SO42-(aq) + H2(g). so by reacting sulfuric acid with aluminium you effectively removed the 3 electrons from the aluminium's outer shell so it becomes aquated in water ie Al3+(aq) that is lossely bounded to water molecules.

 

[~*HSC 4 life*~]

ummm about the covalent/ionic thing, now im confused..maybe its coz ive been thinking too much...you said water was covalent, thats what i thought but then i thought about it more...and you said ionic compounds are those which form between negative and positive ions....so wouldnt water be ionic? H+ and OH- ? or am i going completely offtrack....same thign CaCo3....calcium and carbonate have oppositely charged valenices...so they would be ionic right?? ummm help!

 

[Xayma]

Originally posted by abdooooo!!!
aquated and hydrated... me thinks its the same thing

Well in the sense you are using, where it is dissolved in water, it is in an aqueous stage. Hydrated is where water molecules are found with other molecules many crystals are hydrated and things like urea are.

Originally posted by ~*HSC 4 life*~
and you said ionic compounds are those which form between negative and positive ions....so wouldnt water be ionic? H+ and OH- ? or am i going completely offtrack....same thign CaCo3....calcium and carbonate have oppositely charged valenices...so they would be ionic right?? ummm help!

Calcium Carbonate is ionic since the carbonate takes Calciums electrons (they arent shared at all).

Hydrogen isnt +1 as such, it will always try to share its electron and get another one, however the oxygen has a stronger pull for the electron and hence it spends more time around the oxygen, however the electron shell on Hydrogen is filled part of the time. In an ionic compound it would never be filled, it would of been stripped.

Water is always found as H2O, even in gaseous form. If an ionic substance is heated to melting point the ions have enough energy to seperate and move as individual atoms of the metal and non-metal ions, thats why molten ionic substances conduct electricity.

 

[abdooooo!!!]

Originally posted by Xayma
Well in the sense you are using, where it is dissolved in water, it is in an aqueous stage. Hydrated is where water molecules are found with other molecules many crystals are hydrated and things like urea are.

im sorry if i didn't make myself clear but based on my example the aluminium cation will bond with the sulfate anion ie Al2(SO4)3. this bounds to some water molecule. the number of water molecule would be impossible to determine theoritically, but experimentally it can be determined by calculating molecular mass. so n = is a interger, Al2(SO4)3.n(H2O).

Originally posted by Xayma
ummm about the covalent/ionic thing, now im confused..maybe its coz ive been thinking too much...you said water was covalent, thats what i thought but then i thought about it more...and you said ionic compounds are those which form between negative and positive ions....so wouldnt water be ionic? H+ and OH- ? or am i going completely offtrack....same thign CaCo3....calcium and carbonate have oppositely charged valenices...so they would be ionic right?? ummm help!

well water is covalent for the fact that it has a electronegativity difference between oxygen and hydrogen of less than 1.7, thus its a covalent molecule.

if you get H3O+ and OH- and react them, you'll find that it would be an acid/base reaction involving the transfer of electrons from the base, in this case OH-, to the acid, H+, hence neutralisation (or as i like to call it de-ionisation) has occured and the ionic nature of H+ and OH- has been removed to form a covalent molecule know as H2O... and producing large amount of heat in the process which can severely burn the not so careful chemist.

 

[Wohzazz]

now i'm getting more confused about hydrated or aquated ions...so can we say that hydrated metals such as Aluminium are just Al ion in aqueous? and about that about how many molecules of water bound to Al2(SO4)2, i'm not suppose to know how to find it out experimentaly right?

 

[Wohzazz]

Originally posted by abdooooo!!!
increase in volumn decreases the partial pressure of the three gases involved but does not affect the solid because you can not compress solids as it is already compressed if you know what i mean. hence the decrease in partial fraction will therefore mean a decrease in concentration of this gases.

i thought concentration was molecules or atoms per volume or area, thus, if areas is volume is bigger, concentration even for the solid (which has a fixed number of molecules and atoms) will be decreased

 

[abdooooo!!!]

Originally posted by Wohzazz
i thought concentration was molecules or atoms per volume or area, thus, if areas is volume is bigger, concentration even for the solid (which has a fixed number of molecules and atoms) will be decreased

nah, partial pressure = concentration of gases. but does nothing to solids.

 

[abdooooo!!!]

Originally posted by Wohzazz
now i'm getting more confused about hydrated or aquated ions...so can we say that hydrated metals such as Aluminium are just Al ion in aqueous? and about that about how many molecules of water bound to Al2(SO4)2, i'm not suppose to know how to find it out experimentaly right?

well it has to be an aqueous: aquated, hydrated (aq)... since aqua and hydro = water.

nah you don't need to no how to find them out experimentaly... im not sure of the procedures myself, but the logics are you know the molecular weight of dehydrated aluminium sulfate by using data from periodic table, then you should be able to work out how many water molecule is attached to it by comparing and then using math.