Lab 4 Notes Solutions

are homogeneous mixtures of two or more substances consist of a solvent (larger amount, usually a liquid) and solutes (smaller amount, usually a solid) solutes are uniformly dispersed within the solvent

Concentration of Solution - Molarity Molarity M = moles/liter 1 M = 1 mole/L 1 mole of NaCl has the mass of Na: g/mole + Cl: g/mole NaCl: g/mole How to make a solution of 1M NaCl: Mass out g then dissolve in 1 L water

Concentration of Solutions - % % (m/v) is another frequently used concentration measure mass of solute__ x 100% volume of solution

Types of Solution

Water is the most common solvent. is a polar molecule. forms hydrogen bonds with solutes

Diffusion Passive movement of substances from an area of high concentration to an area of low concentration

Osmosis Diffusion of water across a semipermeable membrane Water flows form from an area of lower solute concentration (hypotonic) to area of higher solute concentration (hypertonic), assume the solute cannot move Isotonic: both areas have the same concentration Semipermeable small molecules can go through, large molecules cannot

Dialysis Filtration of solutions through a selectively permeable membrane. dialysis membranes let water and certain solutes (those that have the right size) move across the membrane to equalize Example: membranes of kidney let water, waste molecules, salt and sugar move across (sugar is reabsorbed!), but blood cells are too big