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Chemical Terms and Conversion Factors
Chemical Terms
Acid
An acid is a substance that releases hydrogen ions
(H+) when dissolved in water. The hydrogen ion is
responsible for the properties of an acid:
Tastes sour
Changes the color of blue litmus paper to red; turns
phenolphthalein (an indicator dye) colorless.
Reacts with many metals to release hydrogen gas.
Alkali (base)
An alkali is a substance that releases hydroxyl
(hydroxide) ions (OH–) when dissolved in water. This
ion is responsible for the properties of an alkali:
Feels soapy or slippery
Changes the color of red litmus paper blue, and
turns phenolphthalein red.
Distillation
The process of changing a liquid to a gas by boiling
and then changing the vapor back to a liquid by
condensation.
Ion
When a substance dissolves in water, it may form
charged particles called ions. Ions can be either positively charged “cations” or negatively charged
“anions.”
KB Value
The relative solvent power of liquids is expressed
by the index number called the Kauri-Butanol Value
(KBV). On this scale, benzene is equal to 100 and all
other liquids are compared to it. The higher the KBV,
the stronger the solvent. A high KBV is usually more
effective in removing oil and grease stains, but a
lower KBV may be safer on some dyes, vinyls, and
other solvent-soluble items.
Neutralization
Neutralization is the reaction between an acid and
an alkali to form water plus a salt. An acid added to an
alkali will completely neutralize or counteract the
alkali, and vice versa, if a sufficient amount is used.
Nonvolatile Residue (NVR)
NVR consists of solvent-soluble substances that do
not evaporate during the drying cycle and consequently are left in the garments. These substances do
not distill over with the solvent and remain behind in
the still residue or cooked filter muck. They may consist of beneficial materials such as detergent and sizing or undesirable materials such as waxes, oils,
and grease.
Oxidation
The process in which a substance combines with
oxygen. An oxidizing bleach adds oxygen to a
substance.
pH
The pH is a measure of the strength of an acid or
alkali by the concentration of hydrogen– ions (H+) in
an acid solution or of hydroxyl (OH ) ions in an
alkaline solution. Acids and alkalies vary in the number of hydrogen or hydroxide ions they produce and
the pH scale is used to rank them.
The pH scale ranges from O to 14. Each step on the
scale increases by a factor of 10. For example, a solution at pH 10 is ten times more alkaline than a solution at pH 9 and 100 times more alkaline than pH 8.
A pH of 7 is the neutral point in the scale; at this point
equal numbers of hydrogen and hydroxide ions are
present. The greater the concentration of hydrogen
ions in a solution, the lower its pH and the more
strongly acidic it is. The greater the concentration of
hydroxyl ions in a solution, the higher its pH and the
more strongly alkaline it is.
Reduction
The process in which a substance gives up its
oxygen. Thus, a reducing bleach removes oxygen
from a substance.
Surfactant
A surfactant is a “surface active agent” which can
be classified into three groups:
Nonionic — a surfactant that does not break up or
dissociate in water to form ions.
Anionic — a surfactant that dissociates in water,
with the water-acting portion being negatively
charged.
Cationic — a surfactant that dissociates in water,
with the water acting portion being positively
charged.
Conversion Factors
Solvent
A substance that can dissolve another substance. In
drycleaning, the following types of solvents are used.
Synthetic Solvents
Perc — Known as perchloroethylene or tetrachloroethylene
Fluorocarbon — F-113, R-113, Freon®-TF, or trichlorotrifluoroethane
(Note: Valclene™ is F-113 with detergent)
Petroleum Solvents
This bulletin was written by Devora Scharff, Assistant Research Chemist.
T-580
No portion of this publication may be reproduced without written permission from IFI.
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