Oceans Flashcards
What are the two types of solvent?
Polar and non Polar
Why do ionic substances only dissolve in polar solvents?
The ion-dipole bonds formed are stronger than the electrostatic forces between the ions
Why don’t ionic substances dissolve in non-polar solvents?
Non polar molecules don’t interact strongly enough with the ions
Why do covalent substances dissolve in non-polar solvents?
Intermolecular bonds between covalent molecules are weak and can be broken by non polar solvents
Why don’t covalent molecules tend to dissolve in polar solvents?
Hydrogen bonds between water molecules are stronger than bonds between covalent molecules and the water.
How do ionic solids dissolve in water?
1) partially positive charge on H attracted to negative ions
2) partially negative charge on O attracted to positive ions
3) Ions separate from ionic lattice and becomes surrounded by water molecules
What is Hydration?
When a molecule becomes surrounded by water molecules
What is an ion called when it is surrounded by water molecules?
Hydrated ion
What is hydration called when the solvent isn’t water?
Solvation
What is the definition of standard lattice enthalpy?
the enthalpy change when `1 mole of an ionic lattice is formed from its gaseous ions under standard conditions
What is a giant ionic lattice?
Positive and negative ions held together by electrostatic attractions in a lattice (formed by ionic compounds)
What charge is lattice enthalpy?
Always negative because bonds and broken and energy is released
What makes standard lattice enthalpy more negative?
It is a measure of bond strength so the stronger the bonding the more negative it is
What is the definition of enthalpy change of hydration?
The enthalpy change when 1 mole of aqueous ions is formed from gaseous ions.
Is enthalpy change of hydration endothermic or exothermic?
exothermic