CHM102 Lecture Notes - Lecture 10: Hydronium, Ethylene Glycol, Motor Oil
Dissolving Ionic Substances
- When ionic substances dissolve in water, their cations and anions separate and
get dispersed amongst the water molecules.
- Polar water molecules attract both cations and anions in such a way that the end
with opposite charge to the ion points toward it.
Dissolving Molecular Substances
1. Ethylene glycol:
- dissolves in water (miscible in water)
- polar compound
2. Motor oil (hydrocarbon):
- does not dissolve in water (immiscible in water)
- non-polar compound
- dissolves in non-polar solvents such as gasoline or CCl4
Factors Affecting Solubility
- Vitamin A is soluble in nonpolar compounds (like fats).
- Vitamin C is soluble in water.
Ionization of Molecular Solutes
- Aqueous solutions of some molecular substances conduct electricity
(electrolytes).
- This is due to the breaking of a bond in a molecule and formation of ions, called
ionization.
- In some cases, only a fraction of molecules is ionized (creating a weak
electrolyte).
- A‒B A+(aq) + B−(aq) H2O
- A‒B ⇋ A+(aq) + B−(aq)
Self-Ionization of Water
- Pure water consists of a number of water molecules in equilibrium with a small
amount of aquated hydrogen ions and hydroxide ions.
- The process in which ions are obtained is called self-ionization of water.
Document Summary
When ionic substances dissolve in water, their cations and anions separate and get dispersed amongst the water molecules. Polar water molecules attract both cations and anions in such a way that the end with opposite charge to the ion points toward it. Dissolving molecular substances: ethylene glycol: dissolves in water (miscible in water) polar compound, motor oil (hydrocarbon): does not dissolve in water (immiscible in water) non-polar compound dissolves in non-polar solvents such as gasoline or ccl4. Vitamin a is soluble in nonpolar compounds (like fats). Aqueous solutions of some molecular substances conduct electricity (electrolytes). This is due to the breaking of a bond in a molecule and formation of ions, called ionization. In some cases, only a fraction of molecules is ionized (creating a weak electrolyte). Pure water consists of a number of water molecules in equilibrium with a small amount of aquated hydrogen ions and hydroxide ions.