Water, the Solvent of Life
Water, the Solvent of Life
KeyPrinciplesThe solvent properties of H,O shaped the evolution of livingthings.TheionizationbehaviorofH,Oand of weakacidsandbasesdissolved in H,O can be represented by one or more equilibriumconstants.Anagueoussolutionofaweakacidanditssaltmakesabufferthat resists changes in pH in response to added acid or base.Enzymes, which catalyze all of the processes inside a cell, haveevolvedtofunctionoptimallyatnear-neutral(physiological)pH
Key Principles The solvent properties of H2O shaped the evolution of living things. The ionization behavior of H2O and of weak acids and bases dissolved in H2O can be represented by one or more equilibrium constants. An aqueous solution of a weak acid and its salt makes a buffer that resists changes in pH in response to added acid or base. Enzymes, which catalyze all of the processes inside a cell, have evolved to function optimally at near-neutral (physiological) pH
Structure and chemical properties of waterWaterisabundantinlivingorganismIntracellularNon-water(40%)water(40%)About60%of humans iswaterWaterincirculatoryInterstitialwatersystem(5%)(15%)Interstitial nta'stufal) betweenorgansand tissues
Structure and chemical properties of water Water is abundant in living organism. Interstitial [ˌɪntəˈstɪʃəl] between organs and tissues
Molecularbondsofwater Water is composed of 2 H atoms covalently bonded to one O atom.L,tetra'hi:drallTheelectronic structureofwateristetrahedral.2covalentbondswithHatoms2setsofunpairedelectronsResultsinapolarmolecule
Molecular bonds of water Water is composed of 2 H atoms covalently bonded to one O atom. The electronic structure of water is tetrahedral. • 2 covalent bonds with H atoms • 2 sets of unpaired electrons Results in a polar molecule [ˌtetrəˈhiːdrəl]
ElectronegativityAmeasureoftheaffinityofanatom's nucleusforitsoutmostelectrons(howstrongthenucleusofanatomholdsontoitselectrons)HHeElectronegativity of the Atoms2.1LiBeCN4NeB01.52.53.51.02.03.04.0ALSiPSClArNaMg1.21.52.53.00.92.21.8/KCaTiACuGaSeBrKrScVCrMnFeCoZnGeAs1.31.51.61.51.81.81.91.60.81.01.61.81.61.82.02.42.83.0RbSrZrRhPdSbYNbMoTeRuCdSnTeXeAgIn2.21.70.81.01.21.41.61.81.92.22.21.91.71.81.92.12.52.6o+8+HfCsBaTawReOsIrPtHgTiPbBiPoAnAuAtLa-LuH1.1-1.20.70.91.31.51.92.22.22.21.91.81.81.92.02.21.72.4-FrRaAc-NoO1.1-1.70.70.96-Polar['poula]Amoleculewithunevendistributionofcharge
Polar [ˈpəʊlə] A molecule with uneven distribution of charge Electronegativity A measure of the affinity of an atom’s nucleus for its outmost electrons (how strong the nucleus of an atom holds on to its electrons) Electronegativity of the Atoms