CHEM 191 Lectures 1and2 Flashcards
what is a mole
the SI unit of the amount of substance. defined as the amount of substance that contains the same number of specified entities as there are in exactly 12g of the 12C isotope.
what is concentration
the amount of solute per volume of solvent
what is the key solvent biologically
water
what is electronegativity
the ability to gain and retain outer shell electrons
what are the bonds between water molecules called
dipole-dipole interactions - hydrogen bonds
are hydrogen bonds weak or strong
weak (10 the strength of a covalent bond) but many joined together can be relatively strong
what are the unusual properties of water
very high boiling and melting point, gets more dense as it melts, the freezing point of water decreases as pressure increases, there are 14 different forms of ice, relatively large surface tension and heat capacity, it has a very high concentration
what is an electrolyte
a substance that dissociates to give ions
what is dissolution
dissolving
what is solvation
the interaction of a solvent with the dissolved solute . when this happens with water it is called hydration
are non-polar molecules soluble in water
no, but their solubility is not zero due to temporary induced dipole bonding
when is a solution formed
when one or more chemical species dissolve in a liquid
what is a solute
a substance that dissolves in a liquid (it can be solid, liquid or gas but it is usually solid)
what is a solvent
a liquid in which the solute dissolves - always in higher concentration - usually water
what is a dilute solution
a solution that has more moles of solvent than solute
what is the difference between dissociation and dissolution
dissolution is the breaking of bonds between molecules - dissociation is the breaking of the bonds within a molecule
what is a strong electrolyte
a compound that completely dissociates in water - the dissociation reaction goes to completion
what is a weak electrolyte
a compound that undergoes incomplete dissociation in water - the dissociation reaction doesn’t go to completion
ionic solids aren’t very soluble in water (don’t dissolve a lot) but of the solid that dissolves it all dissociates into ions. are they a strong or weak electrolyte
strong
