Solubility

Question 1

If a substance dissolves in a solvent, what must happen?

Answer 1

Bonds in the substance must break
Bonds in solvent must break
New bonds are formed between solvent and substance which has greater or same strength of bonds broken in substance and solvent

Question 2

2 types of solvent

Answer 2

Polar solvent
Non polar solvent

Question 3

Polar solvents

Answer 3

Made up of polar molecules
Therefore the bonds between solvent molecules are hydrogen bonds or permanent dipole-induced dipole interactions

Question 4

What type of substance dissolves in what type of solvent?

Answer 4

Non polar substances dissolve in non polar solvents
Polar substances dissolve in polar solvents
(Like dissolves like)

Question 5

Exception to like dissolves like rule (ions)

Answer 5

If the ionic bonding in substance is stronger than hypothetical bonds formed between solvent and substance it will not dissolve

Question 6

Exception to like dissolve like rule (water)

Answer 6

Hydrogen bonding between water is strong so if the hypothetical bonds between water and solute is weaker, it will not dissolve
So will on,y dissolve ionic compounds or other hydrogen bonding substances

Question 7

Ionic substances dissolve in water

Answer 7

Ions in lattice are attracted to opposite charged ends of polar solvent molecule
Pulled apart from lattice = breaks apart ionic bonding
Hydrogen bonds between solvent molecules break
And new bond between ion and solvent molecule is formed

Question 7

What ionic substances won’t dissolve?

Answer 7

Ionic substances with very strong ionic bonding (due to high charges) because this attraction is stronger than attraction to polar molecules

Question 8

Dissolving alcohols in polar solvents (water)

Answer 8

Contain Oh group
So hydrogen bonds can form between from the solvent molecule
However carbon chain is insoluble

Question 8

Relationship to carbon chain length in alcohol to solubility

Answer 8

Longer carbon chain is, the less soluble it is in polar solvents

Question 8

What substances will water not dissolve even if they are polar?

Answer 8

If the substance does not for, hydrogen bonds
If the substance does not have charged ions
Because hydrogen bonds between H2O is too strong to break when dissolving a substance

Question 9

What dissolve non polar substances?

Answer 9

Non polar solvents

Question 10

How do non polar substances dissolve?

Answer 10

By breaking the London forces between non polar solvent and non polar substance
And forming new London forces between each other