BIOL 1201 Lecture : Lecture 4
Document Summary
Readings: pgs 46-63 in campbell biology 9th ed. Mastering biology: on-line homework 1, 2 (due 10 am, before class) Biological importance: living cells are 70-95% water. Avg 90%: solvent for biological reactions, 71% of earth"s surface is covered. Some important properties of h2o: high specific heat 1 cal/g/degree celsius (stabilizes temperatures, high heat of vaporizations 580 cal/g (produces evaporative cooling, maximum density at 4 degrees celsius (ecological importance for organisms living in aquatic habitats) Crystal collapses in liquid, density increases to 4 degrees celsius. Heating causes motion in liquid density decreases above 4 degrees celsius. Solutions - a homogeneous mixture consisting of a solvent and solute(s) Water is an excellent solvent for ionic (charged) or polar (not charged but positive or negative areas) molecules (see figs. Concentration = mass (solute) / volume (solution: in reactions, molecules combine by number, a mole of any compound possesses 6. 02 x 1023 molecules, molarity (concentration) moles per liter of solution (mol/l)
