7.4 – NOTES Solution Concentration

C.4 Dissolving Ionic Compounds Water molecules are electrically polar This means the charges on the atoms in the molecule are shared unequally.   One end is more positive (+) and the other is more negative (-) Instead of having full charges like ionic compounds, the atoms in a polar molecule have partial charges. The partial charges equal out, making the molecule electrically neutral

Water molecules look like

Polar substances are attracted to polar substances and will dissolve many things Water dissolves by pulling molecules away from the top of the other substances until there is nothing left for the water to pull away from

C.6 Solution Concentration Solution concentration The quantity of solute dissolved in a specific quantity of solvent or solution Expressed as a percent g solute x 100 g solution = g solute + g solvent g solution

Equal to pph (parts per hundred) Example: A common IV saline solution used in medical practice contains 4.5 g NaCl dissolved in 495.5 g of water. What is the concentration of this solution, expressed as a percent by mass?

Parts per million (ppm) or parts per billion (ppb) Used to describe levels of contaminants in water or other trace elements As a fraction, they are expressed as Ppm = x _ ppb = x _ 1,000,000 1,000,000,000