Tag: materials we use

Questions Related to materials we use

Sodium hydroxide is found in:

chemistry materials we use soap and detergents soap soap and detergent

  1. lime water

  2. milk of magnesia

  3. window cleaner

  4. soap

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Correct Option: D
Explanation:

$\bullet$ Lime water has $Ca(OH) _2$

$\bullet$ Milk of magnesia has $Mg(OH) _2$
$\bullet$ Window cleaner has $NH _4OH$
$\bullet$ Soap consists of sodium stearate and $NaOH$.

A product obtained by mixing caustic soda with vegetable oils is:

chemistry materials we use soap and detergents soap soap and detergent

  1. acid

  2. base

  3. soap

  4. vinegar

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Correct Option: C
Explanation:

When vegetable oils reacted with caustic soda they produce potassium salt of Carboxylate. (Soap)

$\implies Vegetable\ oil+KOH\longrightarrow \underbrace {R-CO\overset {\circleddash}{O}K} _{soap}$

We can use soap to check the hardness of water.

chemistry materials we use soap and detergents soap soap and detergent

  1. True

  2. False

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Correct Option: A
Explanation:

Soap get precipitated in hard water, but not in soft water.Therefore soaps can be used to check the hardness of water.

Which type of chemical substances is disparlure?

chemistry materials we use soap and detergents soap soap and detergent

  1. Detergent

  2. Antioxidant

  3. Pheromones

  4. Preservative

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Correct Option: C
Explanation:

Disparlure is a pheromones that attracts insects. Pheromones are an additional form of chemical communication that occurs between rather than within individuals.

The soap molecule has a :

chemistry materials we use soap and detergents soap soap and detergent

  1. hydrophilic head and a hydrophobic tail

  2. hydrophobic head and a hydrophilic tail

  3. hydrophobic head and a hydrophobic tail

  4. hydrophilic head and a hydrophilic tail

Show answer
Correct Option: A
Explanation:
The basic structure of all soaps is essentially the same, consisting of a long hydrophobic (water-fearing) hydrocarbon chain tail and a hydrophilic (water-loving) anionic head.

Hence the correct option is A.

Washing soaps produce scum with hard water and not much foam because hard water contains:

chemistry materials we use soap and detergents soap soap and detergent

  1. chalk and sulphur

  2. many dissolved inorganic salts

  3. many suspended particles

  4. organic matter

Show answer
Correct Option: B
Explanation:

Hard water contains salts of calcium and magnesium principally as bicarbonates, chlorides, and sulfates. Ferrous ion may also be present; oxidized to the ferric form. It appears as a reddish brown stain on washed fabrics and enameled surfaces. Water hardness that is caused by calcium bicarbonates is known as temporary, because boiling converts the bicarbonates to the insoluble carbonates; hardness from other salts is called permanent. Calcium and magnesium ions in hard water react with the higher fatty acids off soap to form an insoluble gelatinous curd, thereby causing a waste of the soap.

Face powders are used for a smooth appearance of the skin by covering any unwanted secretions of oil. Which is the main ingredient of face powder?

chemistry materials we use soap and detergents soap soap and detergent

  1. Precipitates

  2. Talc

  3. Zinc oxide

  4. Zinc stearate

Show answer
Correct Option: B
Explanation:

Talc is often considered to be the main ingredient of face powder. Talc also known as French chalk, is a naturally occurring minerals that absorbs moisture and oil. It leaves the skin feeling soft and fresh and can help to control shine.

Ordinary gasoline (petrol) that is used as fuel cars, scooters and automobiles contain many different chemicals that are added in small quantities, each performing an important role. Some of these are mentioned here. Which of the option is false?

chemistry materials we use soap and detergents soap soap and detergent

  1. Soaps used for removing particles of grease from petrol tanks ensure a free flow of petrol

  2. Anti-icing agents are used for depressing the freezing point of particles of ice

  3. Anti-rust agents are used for protecting against corrosion by water

  4. Detergents are used for preventing gums from sticking on the walls of the carbureter

Show answer
Correct Option: A
Explanation:

$\bullet$ Anti- rust agents are used for protecting iron materials against corrosion by water. Example- Redoxide.

$\bullet$ Anti-icing agents are used for depressing the freezing point of particles of ice.
$\bullet$ Soaps only grease particles from clothes, but it can't remove grease from petrol.

Soaps are sodium salts of fatty acids, RCOONa; e.g. $C _{17}H _{35}COO^-Na^+$. It gives an insoluble precipitate / layer with 

chemistry materials we use soap and detergents soap soap and detergent

  1. $Ca^{2+}$ (aq)

  2. $Mg^{2+}$ (aq)

  3. HCl (aq)

  4. All of these

Show answer
Correct Option: D
Explanation:
Soaps are sodium salts of fatty acids. It gives an insoluble precipitate/layer with Calcium, Magnesium ions. It also gives an insoluble layer with HCl acid.

As a cleaning agent, soap suffers from two main drawbacks:

  • It does not function well in acidic solutions because of the formation of insoluble fatty acid 
eg, $CH _3(CH _2) _{16}COO^-Na^+(aq) + HCl(aq) \rightarrow CH _3(CH _2) _{16}COOH(s) + Na^+(aq) + Cl^-(aq)$
  • It forms insoluble precipitates with $Ca^{2+}$ and$ Mg^{2+}$ ions present in hard water, forming a scum 
eg, $2CH _3(CH _2) _{16}COO^-Na^+(aq) + Ca^{2+}(aq) \rightarrow [CH _3(CH _2) _{16}COO^-] _2Ca^{2+}(s) + 2Na^+(aq)$