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Like Dissolves Like and Molecule Ion Attractions

 

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"Like dissolves like" is an expression used by chemists to remember how some solvents work. It refers to "polar" and "nonpolar" solvents and solutes. Basic example: Water is polar. Oil is non polar. Water will not dissolve oil. Water is polar. Salt (NaCl) is ionic (which is considered extremely polar). Like dissolves like, that means polar dissolves polar, so water dissolves salt.

Polar substances WILL dissolve in Polar substances

Non-polar substances WILL dissolve in nonpolar substances  

Non-polar substances WILL NOT dissolve in polar substances. 

Look at the layers in this video

 

Solvents

Solvent Polarity
Ethyl acetate nonpolar
water   polar
chloroform nonpolar

Solutes

Solute Polarity
Iodine nonpolar
copper(II)sulfate ionic (very polar)

 

Molecule-Ion Attractions

This is how water and ions attract. The hydrogen's of water align themselves towards the negative ion (anion), surround it and takes it away.. If the ion is a positive ion (a cation) the oxygen of the water align themselves towards the ion, surround it and takes it away.

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