BIOL 171 Exam 1 Review Notes

Water: solvent of life

 Solution: Homogenous mixture of substance in liquid form
 Solvent: dissolving agent of solution
 Solute: substance that’s dissolved
 Aqueous solution: water is the solvent

Water is a versatile solvent due to it's polarity

Iconic compound dissolved in water  each ion surrounded by sphere of water molecules aka
hydration shell

Water can dissolve compounds made of nonionic polar molecules

Hydrophilic and hydrophobic substances
 Hydrophilic substance
o Has afÏnity of water
 Hydrophobic
o Does not have afÏnity for water
 Oil molecules = hydrophobic
o Have relatively nonpolar bonds

Solute concentration in aqueous solutions

Mole = 6 x 10^23

Molar concentration (M) = number of moles per liter

Acidic & basic conditions affet living organisms
 Hydrogen atom in hydrogen bond between 2 water molecules can shift from one to
another
o Hydrogen atom leaves it's electron behind and transferred as a proton –
hydrogen ion (H+)
o Molecule that lost the proton – hydroxide ion (OH-)
o Molecule with extra proton – hydronium ion (H3O+) aka H+

Concentrations of H+ and OH- are equal in pure water

Adding certain solutes (acids and base) modifies concentration of H+ and OH-

Use pH scale to determine whether solution is acidic or basic