CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
Which statement about soap is correct?
A. Soap molecules have both water-attracting and oil-attracting regions
B. Soap dissolves grease without interacting with water
C. Soap has no ionic or polar component
D. Soap is purely metallic
Correct Answer: A
The amphiphilic structure of soap allows it to bridge water and oily dirt.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
What is the main environmental concern associated historically with phosphate-rich detergents entering lakes?
A. Eutrophication
B. Loss of all dissolved salts
C. Ozone creation in lakes
D. Formation of diamonds
Correct Answer: A
Excess phosphate can stimulate algal growth, contributing to eutrophication and oxygen depletion.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
Which component is often added to detergents to improve cleaning by binding hardness ions?
A. Noble gases
B. Radioisotopes
C. Pig iron
D. Builders
Correct Answer: D
Builders such as phosphates or alternatives can soften water and improve surfactant performance.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
What is a surfactant?
A. A substance that lowers surface tension and helps water interact with oils or surfaces
B. A metal used only in batteries
C. A substance that always increases freezing point
D. A gas that destroys water
Correct Answer: A
Surfactants reduce interfacial tension and aid wetting, emulsification and cleaning.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
Why are many synthetic detergents more effective than soap in hard water?
A. They convert hard water into steam
B. They contain no carbon
C. They always make water acidic
D. They generally do not form the same insoluble precipitates with calcium and magnesium ions
Correct Answer: D
Many detergent surfactants remain soluble in the presence of hardness ions.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
Why does soap work poorly in hard water?
A. Soap evaporates instantly
B. Hard water has no molecules
C. Hard water contains no hydrogen
D. Calcium and magnesium ions form insoluble scum with soap
Correct Answer: D
Divalent calcium and magnesium ions react with soap anions to form insoluble salts.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
What structure forms when soap molecules surround grease droplets in water?
A. Crystals of sodium chloride
B. Micelles
C. Atomic nuclei
D. Gas bubbles only
Correct Answer: B
Micelles trap oily material in their hydrophobic interiors while hydrophilic heads face water.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
What part of a soap molecule interacts most strongly with grease and oil?
A. Water molecule
B. Hydrophobic hydrocarbon tail
C. Hydrophilic head only
D. Sodium ion only
Correct Answer: B
The nonpolar hydrocarbon tail dissolves or embeds in nonpolar grease and oil.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
What part of a soap molecule is attracted to water?
A. Carbon soot particle
B. Metallic core
C. Hydrophilic ionic head
D. Hydrophobic hydrocarbon tail
Correct Answer: C
Soap molecules are amphiphilic: their ionic or polar heads interact with water while hydrocarbon tails interact with grease.
CSS - PMS - CCE - PCS - General Science
Applied Chemistry - Soap & Detergents
Soap is commonly produced by reacting fats or oils with a strong alkali in a process called what?
A. Saponification
B. Polymerization
C. Fermentation
D. Distillation
Correct Answer: A
Saponification converts triglycerides and a strong base into glycerol and salts of fatty acids called soaps.