5A-QA9 (D9, May 12)

Which of the following statements concerning a soapless detergent are correct?

(1) It can be prepared by heating a cooking oil with sodium hydroxide solution.

(2) It acts as a wetting agent by reducing the surface tension of water.

(3) It acts as an emulsifying agent in the cleaning process.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following statements concerning soaps are correct?

(1) They are esters.

(2) They can reduce the surface tension of water.

(3) Their aqueous solutions are alkaline.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

Which of the following statements is correct for a soapy detergent but incorrect for a soapless detergent?

• Its structure consists of a hydrophilic part and a hydrophobic part.

• It forms lather when shaken with distilled water.

• It can be made by reacting a vegetable oil with an alkali.

• It acts as an emulsifier in the cleaning process.

A student heated a mixture of fat and sodium hydroxide solution for some time. He then added the mixture to a beaker of saturated sodium chloride solution. A white solid was formed. Which of the following statements concerning this experiment is/are correct ?

(1) The reaction between fat and sodium hydroxide is esterification.

(2) The white solid is a soap.

(3) The white solid contains salts of alkanoic acids.

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only

Dilute ammonia solution is used in domestic glass cleansers because

(1) it can saponify grease.

(2) it is non-corrosive.

(3) it contains ammonium ions which can emulsify grease.

Which of the above statements is/are correct ?

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only

Soap was prepared by heating fat with sodium hydroxide solution for some time. Concentrated sodium chloride solution was then added to the resulting mixture. The purpose of adding concentrated sodium chloride solution is

• to help precipitation of the soap.

• to enhance the cleansing power of the soap.

• to reduce the alkalinity of the soap.

• to act as a preservative for the soap.

A detergent has the structure as shown. Which of the following statements concerning this detergent is correct ?

• It is non-biodegradable.

• It functions well in hard water.

• It can be manufactured from vegetable oils.

• The portion, CH₃(CH₂)₁₀CH₂–, is hydrophilic.

A detergent has the structure as shown. Which of the following statements concerning the detergent is correct?

• Its hydrocarbon chain is hydrophilic.

• It can be manufactured from vegetable oil.

• It is readily degraded by micro-organisms.

• It acts as an emulsifier in the cleaning process.

Which of the following statements concerning these detergents is correct?

• The hydrocarbon tail of detergent III is hydrophilic.

• Both detergents I and II form scum with seawater.

• Detergent III causes more serious pollution problems than detergent I when discharged into rivers.

• Both detergents II and III are made from fats.

Which of the above is/are soapless detergent(s)?

• detergent I only

• detergent III only

• detergents I and II only

• detergents II and III only