O - Solubility Flashcards
Solutes dissolve best in solvents with…
…similar intermolecular forces.
What happens when something dissolves?
Bonds within the solvent break and new bonds between the solvent and solute are made.
Generally speaking, when won’t substances dissolve?
If the bonds to be broken are stronger than those that will be formed.
How many main types of solvent are there?
2
What are the 2 main types of solvent?
Polar and non-polar.
Give an example of a polar solvent
Water
Give an example of a non-polar solvent
Hexane
In what type of solvents do most ionic substances only dissolve in?
Polar solvents.
Why do most ionic substances only dissolve in polar solvents?
Because non-polar molecules don’t interact strongly enough with ions to pull them away from an ionic lattice. The electrostatic forces between the ions are way stronger than any bonds that could form between the ions and non-polar solvent molecule. The ion-dipole bonds are formed between ionic substances and polar solvent molecules, on the other hand, are strong enough to dissolve the solid.
In what type of solvents do most covalent substances only dissolve in?
Non-polar solvents.
Why do most covalent substances only dissolve in non-polar solvents?
Because the intermolecular bonds between covalent molecules tend to be pretty weak. They can be broken by non-polar solvent molecules. Covalent substances don’t tend to dissolve in polar solvents though. For example, iodine doesn’t dissolve much in water - the hydrogen bonds between water molecules are stronger than the bonds that would form between water molecules and iodine molecules.
What are all solvents that aren’t water called?
Non-aqueous solvents.
What type of solids dissolve in water?
Ionic solids.
Ionic compounds can be dissolved in water to make what?
An aqueous solution.
Why do ionic compounds dissolve in water to make an aqueous solution?
1) The H-O bonds in water are really polar, which means the H atoms have a positive partial charge and the O atoms have a negative partial charge.
2) This means ion-dipole bonds can be formed between water molecules and the dissolved ions.
3) The positive partial charges on the H atoms are attracted to the negative ions and the negative partial charges on the O atoms are attracted to the positive ions.
4) The ions separate from the ionic lattice and become surrounded by water molecules.
5) The process of the ions being surrounded by water molecules is called hydration and ions surrounded by water molecules are called hydrated ions. If the solvent isn’t water, this process is called solvation.
6) Unless the ionic bonds in the lattice are really strong, the ion-dipole bonds will be strong enough to pull the lattice apart. This is why most ionic substances are soluble in water.
