Lab 4 Notes

Solutions

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: 22.99 g/mole + Cl: 35.45 g/moleNaCl: 58.44 g/mole

How to make a solution of 1M NaCl: Mass out 58.44 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