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Postby ClaireHW » Tue Nov 07, 2017 11:13 pm

Compounds having bonds with a high covalent character tend to be less soluble in water than similar compounds that have low covalent character. Use electronegativities to predict which of the following compounds is more soluble in water;
a) AlCl3 or KCl
b) MgO or BaO

Could you just briefly explain this concept.

(Claire Woolson Dis. 3J)

Joyce Lee 1C
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Re: 3.79

Postby Joyce Lee 1C » Wed Nov 08, 2017 9:41 am

You can use the difference in electronegativity to figure this out. If the electronegativity difference > 2, then it's an ionic bond. If the electronegativity difference < 1.5, then it's a covalent bond.

Figure 3.12 on page 92 of the textbook gives the electronegativities of the main group elements.

a) Al has an electronegativity of 1.61 and Cl is 3.16
The difference in electronegativity for AlCl3 is 1.55
K: 0.82 and Cl: 3.16
the difference in electronegativity for KCl is 2.34
Because the difference in electronegativity for KCl is greater, the compound KCl will be more soluble.

b) Mg: 1.31
O: 3.44
Ba: 0.89

MgO: 2.31
BaO: 2.55
Because the difference in electronegativity for BaO is greater, BaO should be more water soluble

Kelly Kiremidjian 1C
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Re: 3.79

Postby Kelly Kiremidjian 1C » Wed Nov 08, 2017 9:50 am

Also remember that atoms with a similar number of valence electrons are more likely to equally share electrons and have a more covalent character. This is in contrast to ionic character, where one atom is monopolizing the electrons.

Nick Bazett 1F
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Re: 3.79

Postby Nick Bazett 1F » Sat Nov 10, 2018 9:42 pm

So the compound with the greater difference in electronegativity will always be more soluble in water?

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