justifiable on historical grounds, this name is not rec-
ommended, since Bronsted relations are known to
apply to many uncatalyzed and pseudo-catalyzed reac-
tions (such as simple proton [HYDRON] transfer reac-
tions). The term pseudo-Bronsted relationis sometimes
used for reactions that involve NUCLEOPHILIC CATALYSIS
instead of acid-base catalysis. Various types of Bronsted
parameters have been proposed, such as βlg, βnuc, and
βeq for leaving group, nucleophile, and equilibrium
constants, respectively.
See alsoLINEAR FREE-ENERGY RELATION.
Brownian movement The rapid but random motion
of particles colliding with molecules of a gas or liquid
in which they are suspended.
buckminsterfullerene(fullerene or buckyball) An
ALLOTROPEof carbon containing clusters of 60 carbon
atoms that vary in size, bound in a symmetric polyhe-
dral structure. Robert Curl, Harold Kroto, and Richard
Smalley discovered buckminsterfullerene, C 60 , the third
allotrope of carbon, in 1985. Using laser evaporation
of graphite, they found clusters of which the most com-
mon were found to be C 60 and C 70. For this discovery
they were awarded the 1996 Nobel Prize in chemistry.
The actual molecule was named after American archi-
tect Richard Buckminster Fuller (1895–1983) because
its structure resembled his geodesic dome.buffer A molecule or chemical used to control the pH
of a solution. It consists of acid and base forms and
minimizes changes in pH when extraneous acids or
bases are added to the solution. It prevents large
changes in pH by either combining with H+or by
releasing H+into solution.
See alsoPH SCALE.buffer capacity The ability of a buffer solution to
absorb added alkali or acid while maintaining the solu-
tion’s pH.bulk flow(pressure flow) Movement of water (or
any other fluid) due to a difference in pressure between
two locations. The movement of solutes in plant
phloem tissue is an example.Bunnett-Olsen equations The equations for the
relation between lg([SH+]/[S]) + Hoand Ho+ lg[H+] for
base S in aqueous mineral acid solution, where Hois
Hammett’s acidity function and Ho+ lg[H+] represents
the activity function lg(γSγH+)/γSH+for the nitroaniline
reference bases to build Ho.
lg([SH+]/[S])–lg[H+] = (Φ–1)(Ho+ lg[H+]) + pKSH+
lg([SH+]/[S]) + Ho= Φ(Ho+ lg[H+]) + pKSH+
See alsoCOX-YATES EQUATION.buret A length of volumetric glass, usually graduated
in 0.1-ml intervals, that is used to deliver solutions in a
quantitative manner.buret 35A carbon allotrope that contains clusters of 60 carbon atoms
bound in a highly symmetrical polyhedral structure