Aqueous Solutions

Solution Homogeneous mixture Solute – substance be dissolved Solvent- substance solute is dissolved in

Water As Solvent Water is polar molecule O atom has a greater attraction for electrons than H O has partial negative charge (δ - ) H has partial positive charge (δ + )

Hydration Positive ends of water molecules are attracted to negative ions in ionic solid Negative ends of water molecule attracted to positive ions Each ion is then surrounded by water molecules C:\Program Files\General Chemistry 4.0\General Chemistry 4.0.exe

Dissociation When ionic substances dissolve in water, they break up into their ions NH 4 NO 3 (s)  NH 4 + (aq) + NO 3 - (aq)

Solubility How well substance dissolve Some substances are more soluble than others Very polar non-ionic substances may dissolve in water as well as ionic ones “like dissolves like” E:\TV11V44.MOV E:\TV11V09.MOV

Electrolytes Solutions that conduct electricity Conductivity comes from the presence of ions More ions, better conductivity

Strong Electrolytes Very soluble salts, strong acids, and strong bases Strong acids – ionize completely in water to form H + ions E:\TV13A01.MOV Strong bases – ionize completely to form OH - ions

Weak Electrolytes Don’t ionize completely Weak acids HF(s)  H + + F - E:\TV13A02.MOV Weak bases NH 3 + H 2 O  NH OH -

Non-Electrolytes Don’t ionize at all