Chapter 15.3 Water As A Solvent Flashcards
What are aqueous solutions
Are formed when solid, liquid or gas is dissolved in water.
Solute - substance being dissolved
Solvent - liquid in the substance is dissolved in
**Aqueous solution solvent always = water
What are the common characteristics of solutions? (3)
- the solute and solvent cannot be distinguished from each other = HOMOGENOUS
- dissolved particles are too small to see
- the amount of dissolved solute can vary from 1 solution to another
What occurs during DISSOLUTION (3)?
Dissolution = process of a substance dissolving in another substance
* when two substances are liquids = miscible
During dissolution process the following occurs.
- particles of the solute are separated from one another
- particles of the solvent are separated from one another
- solute and solvent particles are attracted to each other
For a solution to form, the solute particles must interact with the solvent molecules.
* the solute particles are surrounded by solvent molecules and carried throughout the solution.
What forces are involved in dissolving?
For a substance to dissolve the attractive forces that form between the solute and solvent particles must be sufficing to overcome the forces between the particles in solute and solvent molecules.
- Forces hold particles of the substance (solute) together before it is added to the solvent
- Forces hold the solvent molecules together. In water = hydrogen bonds
- Forces can form between the solute particles and solvent molecules if the substance dissolves
Polar and non - polar solvents. Which one is soluble?
Polar molecules have a permanent dipole and an uneven distribution of charge, and are symmetrical
*** WILL generally DISSOLVE substances consisting of polar molecules or charged ions but not solute made up of non-polar
Non- Polar molecules have bonds with an equal distribution of valence (outer shell) electrons, therefore there is no charge on either end of the molecule and the molecule is symmetrical
** can DISSOLVE NON POLAR molecules but not polar molecules or ions.
Use ‘like dissolves like’ to predict if something will dissolve in a solvent
For a substance to be soluble … what is needed? (3)
For a substance to be soluble,
- the particles of solute and solvent separate
- the solute and solvent must be attracted to each other,
- the solute - solvent interactions must be stronger than the solute-solute and solvent- solvent interactions.- MEANING THE ATTRACTIVE INTERMOLECULAR FORCED MUST BE OVERCOME TO SUCESSFULLY DISSOLVE