sacrificial anode The ANODEin a CATHODIC PRO-
TECTIONsystem. For cathodic protection, a more active
metal is placed next to a less active metal. The more
active metal will then serve as an anode and will
become corroded instead of the less active metal. The
anode has an oxidation potential that is greater than
that of the other metal, so it is preferentially oxidized
and is called a sacrificial anode.

sacrificial hyperconjugation See HYPERCONJUGA-
TION.

saline Salty. Describes the condition of water that has
a high concentration of salt, making it unfit for human
consumption.

salinity A measure of the salt content of water, soil, etc.

salt An ionic compound made up of a cation and an

anion and produced in neutralization reactions, e.g., an

acid combined with a base produces a salt.

salt bridge A U-shaped tube containing an elec-

trolyte that connects two HALF-CELLs of a VOLTAIC

CELLallowing ion flow without extensive mixing of the

different solutions. Also a permeable material soaked in

a salt solution that allows ions to be transferred from

one container to another.

sandwich compound A class of organometallic

compounds (organic compound with one or more

metal atoms in its molecules) whose molecules have a

metal atom or ion bound between two plane parallel

organic rings, e.g., metallocenes [Metal(C 5 H 5 ) 2 ]; fer-

rocene [Fe(C 5 H 5 ) 2 ].

saponification The chemical reaction that makes

soap. The reaction between triglycerides and sodium or

potassium hydroxide (lye) that produces glycerol and

soap.

saprobe Any organism that obtains its nutrients and

energy from dead or decaying matter. Formerly called

saprophyte.

241

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Sacrificial anode. The anode in a cathodic protection system