Page 291 - Chemistry eBook

Ionic vs.
Covalent Compounds– Boiling and Freezing Points
Ionic compounds have lower freezing points and higher boiling points than covalent compounds.
• Why? Ionic compounds split, so more moles are created,
and there’s more solute. The more solute a solution has, the lower the freezing point and the higher the boiling point.
Ionic compound: KCl splits into K and Cl, which total 2 moles.
Covalent compound: H2O doesn’t split, so it remains as 1 mole.
Since there are more moles of the ionic compound, there is more solute, so the freezing point is lower and the boiling point is higher.
Salt (an ionic compound) is added to snow to lower the freezing point. This way the snow won’t freeze unless it gets a lot colder.
UNIT 7: SOLUTIONS / SOLUBILITY © 290