CHEM 191 Lecture 5 Flashcards
what are the three types of chemical reactions
electron transfer
precipitation
acid-base reactions
what are the lewis definitions for acids and bases
a lewis acid is an electron pair acceptor and a lewis base is an electron pair donor
what is a coordinate or dative bond
a type of covalent bond in which the shared pair of electrons comes from only one of the bonding atoms
what is an adduct
a product
what is the Bronsted Lowry definition of an acid and base and where are these definitions mostly used
an acid is a proton donor and a base is a proton acceptor - to describe acid base behaviour in an aqueous solution
what does amphiprotic mean
a substance that can act as either an acid or a base (water)
what are acid base pairs
pairs of acids and bases that differ by only a proton (the acid is always the one with an extra proton)
what makes a compound an acid
a proton attached to an electronegative element via a polar bond
what makes a compound a base
because the base needs to make a new bond to the H+, it needs to have at least one lone pair of electrons.
what is Kw
the auto ionisation of water also know as the autoprotolysis constant
what is the equation to go from pH to [H3O+]
[H3O+]=10^-pH
pH + pOH =
14 at 25 degrees celsius
can the concentrations of OH- and H3O+ vary independently
no, due to the form of the autoprotolysis of water expression - if one increases the other must decrease
can a pH of 6.66 be neutral
yes but not at 25 degrees celsius
what is a strong acid
an acid that donates its proton essentially completely to water. acids which donate their protons on reactions that go to completion
how can we calculate the concentration of H3O+ in strong acids (and the concentration of OH- in strong bases)
using stoichiometry
what is a strong base
a base that reacts with water to give essentially complete formation of OH- ions - or an ionic compound that dissolves completely in water to give OH-. for example, NaOH.
do we need to take into account the H3O+ and OH- produced by the auto ionisation of water when calculating pH
usually it is negligible except when we have very dilute solutions
