Covalent Bonds

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Covalent Bonds

Postby paytonm1H » Thu Nov 08, 2018 7:04 pm

Hi all!

I'm working on question 2D.7(a), where its asking if AlCl3 or KCl bonds are more covalent. The difference between the electronegativity of AlCl3 is 1.5 and the difference for KCl is 2.2. Since covalent bonds are identified as having a EN difference of <1.5, shouldn't the AlCl3 be considered more covalent?

The solutions manual says that KCl should be more soluble than AlCl3. Can someone please help me understand why this is?


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Re: Covalent Bonds

Postby Chem_Mod » Thu Nov 08, 2018 8:40 pm

Essentially, compounds having bonds with high covalent character tend to be less soluble in water. If you apply the concept of polarizing power, Al3+ from AlCl3 has higher polarizing power than K+ from KCl because it's smaller and has a higher charge. Higher polarizing power results in ionic bonds with higher covalent character. Since AlCl3 has higher covalent character, it is less soluble in water than KCl.

Celine Hoh 2L
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Re: Covalent Bonds

Postby Celine Hoh 2L » Thu Nov 08, 2018 9:18 pm

Yes, for the reasons above AlCl3 is actually ionic with covalent character.

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