Water of hydration of Group 2 Chlorides

[clarisse]

I'm trying to find some information on trends in the chemical properties of MgCl2, CaCl2, SrCl2, BaCl2, like their pH, their solubility in water and most important of all on their water of hyrdation but I can't find any relevant information or serious explanations... !!!

so if anybody can help i would be really grateful because i have to do my lab write up for tomorrow

[5614]

Does this:

http://www.chemguide.co.uk/inorganic/group2/problems.html

help???

 

BeCl2 is covalant, whereas all the other group2 chlorides are ionic compounds. So we know that apart from BeCl2 all the group 2 chlorides will disolve in water. I just know that, it might be on that link, I just saw the title so linked to it, it's your work, you can read it!

[P-man]

I thought that they were all (or at least most of them were) covalent. Also, BeCl₂ is one of the most stable Group 2 compounds, so that's why it doesn't dissolve in water. Their pH? Look around the Internet, you should find something .

[woelen]

All of the earth alkaline metal chlorides are purely ionic, except the BeCl2, which is intermediate between ionic and covalent.

 

When dissolved in water, expect the pH of solutions of all of them to be close to 7, except for BeCl2. This compound probably is somewhat acidic on dissolving in water, but I just reason from theory, I have no practical figures.

[5614]

In BeCl2 the Be is too electronegative to give up it's electrons so it cannot form an ionic bond, however BeCl2 still displays properties of an ionic compound... I think this is why it is described as "between ionic and covalent".

 

When BeCl2 dissolves in water hydrated beryllium ions are acidic, these ions are very electronegative so attract the electrons towards itself, making the hydrogen ions even more positive than usual.

 

When this reaction is hot (and it is exothermic so it usually is!) there is even enough energy for the chloride ions to remove the hydrogen ions to produce hydrogen chloride gas.