7.3 Polarity in Molecules

Question 1

What principal is used to predict whether of not a specific solvent can dissolve a specific solute

Answer 1

To predict whether or not a specific solvent can dissolve a specific solute remember the principal or “like dissolves like”

Question 2

What does “like dissolves like” mean

Answer 2

Polar solvents can dissolve polar and ionic solutes
Non polar solvents can dissolve non polar solutes
Meanwhile a non polar solute doesn’t dissolve well in a polar solvent, and vice versa

Question 3

What are some common polar and non polar molecules

Answer 3

Alcohol or HCl are both polar and so dissolve better in polar water than oil or CCl4 both non polar

Question 4

What is a notable solvent

Answer 4

Another notable solvent is diethyl ether, it is slightly polar, but typically acts as a non polar substance

Question 5

what are ionic solvents and solutes

Answer 5

Ionic solvents exist but are rare outside labs, and aren’t covered in Chem11

Ionic solutes are common, and act as extremely polar solutes

Question 6

How are molecules non polar

Answer 6

Covalent bonds are made of shared pair(s) of electrons, if the electrons are equally shared between atoms the molecule is not polar

Question 7

How are molecules polar

Answer 7

If one atom attracts electrons better (i.e has higher electronegativity) atoms will spend more time around that/those atom(s), making the molecule polar, as one part is more negative, and one part is more positive.

Question 8

How does symmetry affect polarity

Answer 8

Always consider the effect of symmetry. As a molecule like CCl4 has carbon and chlorine, Cl having a higher electronegativity, but due to its symmetry the 4 Cl atoms compete and it is non polar, even though individual bonds may be polar