Cations That Act as Lewis Acids

Some cations, since they are positively charged and have lost some electrons, have empty orbitals that allow them to also act as Lewis acids. Consider the hydration process of the Al ion discussed in Section 15.8 shown here  

The aluminnm ion acts as a Lewis acid, accepting lone pairs from six water molecules to form the hydrated ion. Many other small, highly charged metal ions also act as Lewis acids in this way. 

Energy About 83% of U.S. energy comes from fossil fuel combustion. Source U.S EIA Annual Energy Review 2011 

Source National Atmospheric Deposition Program, National Trends Network 

Hydrogen ion concentration as pH from measurments made at the Central Analytical Laboratory, 2010 

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